Megasquirt Ignition Options (falling edge, stock distributor, etc)

[Ondonti]

After looking at some files and also datalogs, I am finding that Joe, just like Ed, has high timing error.
Both are using Rising edge ignition input capture and using some trigger angle offset like 75 degrees. Nathan Wilbur was using 64 degrees, "rising edge" but he posted no datalogs.

Joe had -12.7% to 12.7% error during an actual pull and his error is less during cruising (about half). The error constantly goes up and down extreme to extreme almost like each ignition event is 12-24% different from the one before it as far as actual timing....

My timing error is about 3% to -2.9% at most during pulls. My error also spends most of its time at less then those peak errors and during shift or decell is slightly more erratic (not really important).

I was using falling edge and much lower timing error but my car is unhappy after sitting so I have been looking at others files including Joe's very recent stuff to make sure I didn't mess more things up in my tune when it got corrupted.

I don't understand the reasoning behind rising edge use or how people are deciding to set it up. I just set falling edge and did nothing else per DIY forever ago. Never thought about it.

I did try checking my timing with a light just using the starter to bump it over. it bounced around a bit but I got it down to around 12 degrees with manual adjustment. I did not disconnect any sensors. I don't know what that represents with MSII Extra when the engine is not running!!!!

[Sundance 6g72]

megasquirt might have a cranking timing setting. best to set it with the motor running :p

i need to fix my cam seal so i can investigate this.

[Shadow24]

What code revision are you using or basing your theory on? There has been a lot of work done on the MSII-Extra code in the last couple years. I am updating my MS when it gets re-installed (hopefully soon) as I am over a FULL revision out of date (2.x.x to 3.2.5 or latest).

[Ondonti]

What code revision are you using or basing your theory on? There has been a lot of work done on the MSII-Extra code in the last couple years. I am updating my MS when it gets re-installed (hopefully soon) as I am over a FULL revision out of date (2.x.x to 3.2.5 or latest).

3.2.1

I am just looking at datalogs and the timing error is something we have talked about in the past. I am more concerned with rising edge vs falling edge (per DIY) but I noticed this while investigating differences in peoples setups.

[Shadow24]

hmmm, it looks like the DIYautotune article defaults to the 6-"tooth" input. Has anyone tried using the MSII-extra wheel decoder and the high data rate 360-10 input?

Was Ed's issue on the 12v, not his new 24v 3.5?

[Ondonti]

hmmm, it looks like the DIYautotune article defaults to the 6-"tooth" input. Has anyone tried using the MSII-extra wheel decoder and the high data rate 360-10 input?

Was Ed's issue on the 12v, not his new 24v 3.5?

Not sure if his problem went away or if this was a distributor problem or if he had this problem while also trying a trigger wheel on the crank.
I don't know much about the decoder but that does sound cool.

[Shadow24]

It probably is worth some investigation as my thought is that the 6 tooth isn't as accurate due to its lack of resolution. If your able to run a 360-10 wheel and still run the distributor, I think that would increase the accuracy of the ignition timing where rising or falling edge means +-1* variance at most (guestimate).

[Sundance 6g72]

i dont even know what this 'problem' is or how it woll effect me :(

[Shadow24]

it is an ignition accuracy issue that we are referring to. Ondonti is bringing up the fact that multiple installations using the 6-"tooth" low data rate input from the 12v distributor tends to have a fair variance in asked for ignition timing vs. actual observed timing. The initial thought was that the capture mode (rising edge/front of the tooth vs. falling edge/back of the tooth) could be one possible issue.

Possibly switching to the high data rate input via the wheel decoder in the MSII-extra firmware may provide better timing accuracy all around as it goes from 6 "teeth" to 350 "teeth" (360 with a gap of 10 teeth, similar to a 36-1 EDIS trigger wheel).

If you are running OK as is, it probably isn't that big of an issue, but more of an area that can be improved upon.

[c2xejk]

I had the "problem" when position was with the original 3L 12v distributor. It was still there when I switched to the 36-1 wheel. And I just checked, it is there with my current 3.5L 6g74 distributor setup.

So far I have yet to see reason to believe that is any kind of "real" issue. I don't know what timing err % is or how it is calculated...

[shackwrrr]

Howabout modding the distributor and making a 72-2 wheel for it (36-1 equivalent at crank speed) Then using a VR or Hall sensor. No need to keep the distributor function since wasted spark would be a simple addition. I have no 3.0 experience other than seeing them in the junkyard so dont hate on my idea too much.


Also, since the Dizzy drive is off a cam, a sloppy timing belt could cause some error. Just like a neon with a bad hydro tensioner setting a cam sensor performance code.

[Ondonti]

I had the "problem" when position was with the original 3L 12v distributor. It was still there when I switched to the 36-1 wheel. And I just checked, it is there with my current 3.5L 6g74 distributor setup.

So far I have yet to see reason to believe that is any kind of "real" issue. I don't know what timing err % is or how it is calculated...

So are you running rising edge with that as well? I feel there must be something going on there for our values to be so different and its possible that no matter how good your wheel is, that MS is not up to the task of using that information properly...
I think 6% variance in my datalogs is a lot better then 24% variance though I agree that the meaning behind that statistic is unknown to me beyond what I assume (what Shadow 24 says, timing demanded vs timing observed).
Joes timing is up 12+% up and down seemingly each cycle. That is equivilent to seeing 22.5 degrees and then 17.5 degrees of timing when you were demanding 20 degrees. My timing error is equal to 20.6 up and 19.4 degrees down when demanding 20 degrees. Even that amount of error would be a problem if I was pushing the limits. I have friends who talk about huge gains from less then 1 degree of timing (getting timing "right" vs close).

I know there are more accurate ways to measure crankshaft position but it would help if someone (obviously not me) was more familiar with the limitations of megasquirt to use those measurements. It is possible that our low data rate used properly functions better then other setups in real life.

BTW I am doing some reading and others seem to be capping off at 12.7% but I need to read more. They are reporting problems associated with error and ways they think they can solve it. Some using 36-1 wheels. Old thread I was looking at (2010).

[Shadow24]

My personal experience with a 36-1 and EDIS was a pretty stable and accurate ignition timing... Which thread are you looking at Ondonti?

Also, are you and Ed running the original B&G MSII code or are you both running the MSII-Extra? Everything I have read supports the MSII hardware being more than sufficient for accurate timing, provided you have a good clean input. For instance, the base code runs fast enough for .1* accuracy in the ignition table, so it would seem that there is something external of the MS that probably is causing the timing error...

[c2xejk]

MS2-Extra. I should note that most of the time the value is much less, there are just a few short times were the error is larger. So far I am still not sure that my timing is ever off by any significant amount...

When I last looked there was talk that Timing Err % really didn't mean much the way it was calculated. Some talk of changing it but I have not heard anything about a change.

[Sundance 6g72]

What if you looked that the timing advance in a datalog and then looked to see what it says in the timing map at that exact moment. IE. You are doing a pull and are at 200kpa x 4000rpm and the log says you are running 25*... if your timing table is demanding 25*, then what is the problem?


Im curious in the difference between rising edge and falling edge. Every once and a while i get this slight 'ignition miss' or something that I always thought was a lean condition but im not sure.

[c2xejk]

Does MS show the "actual advance" or the "desired advance"?

[Ondonti]

Does MS show the "actual advance" or the "desired advance"?
Another bit of information that would help in understanding datalogs.

Joe's error is extreme and constant.

BTW One person was talking about the clearances on their VR setup and how that was creating error but that trying to improve error caused other problems.

This is just what I was reading last night.
http://www.msextra.com/forums/viewtopic.php?f=101&t=36666

[Sundance 6g72]

"joe's is extreme and constant" Thats fantastic :/ I should tell all the people I win against that My ecu has no idea how much timing it's really running and that its a mini van motor with an ebay turbo VROOOOOOOOOOOOOOOM

[Shadow24]

Does MS show the "actual advance" or the "desired advance"?
I believe that the MS logs the "requested" advance, i.e. whatever advance is needed for the given conditions after adding or subtracting for temperature, RPM, MAP etc (see the timing equation in the megamanual for more specifics). If that value differs from the "observed" advance, as recorded visually with a timing light, then there may be an issue. Again, if there is a confirmed error %, it may be due to the low data rate input from the 6-"tooth" part of the distributor.

Also, that thread on msextra.com is from '10, and per Ken, the % off value was borderline useless due to no smoothing in the code that derived the % off value. With 2+ years additional work on the MSII-Extra code since that thread/post, I would suspect that if you did a fixed timing and checked it with a light, you wouldn't get much variation.

[Sundance 6g72]

when I set the timing, its spot on.

[Ondonti]

I believe that the MS logs the "requested" advance, i.e. whatever advance is needed for the given conditions after adding or subtracting for temperature, RPM, MAP etc (see the timing equation in the megamanual for more specifics). If that value differs from the "observed" advance, as recorded visually with a timing light, then there may be an issue. Again, if there is a confirmed error %, it may be due to the low data rate input from the 6-"tooth" part of the distributor.

Also, that thread on msextra.com is from '10, and per Ken, the % off value was borderline useless due to no smoothing in the code that derived the % off value. With 2+ years additional work on the MSII-Extra code since that thread/post, I would suspect that if you did a fixed timing and checked it with a light, you wouldn't get much variation.
Would have been nice for him to give an explanation of what the code was doing regardless of its likelihood of giving bad numbers. Another thing that annoys me about MS.
I still don't see why people are or were directly ignoring the setup advice from DIY.

[Shadow24]

Would have been nice for him to give an explanation of what the code was doing regardless of its likelihood of giving bad numbers. Another thing that annoys me about MS.
I still don't see why people are or were directly ignoring the setup advice from DIY.

It looks like he addressed it in a sense on the last post...

As I said, currently the timing error % is so jittery as to be useless. I would not pay any attention to it at all until we get some sort of smoothing in.

It is only telling when it expected to see the next tooth on your wheel compared to when it actually saw it, and says nothing about actual timing accuracy.

In fact, I'll probably remove it until we come up with a better calculation for it.

Ken
What part of DIY's writeup is being ignored?


Sundance 6G72 - If your seeing accurate timing from the MS, i seriously doubt you have anything to worry about

[Ondonti]

It looks like he addressed it in a sense on the last post...

What part of DIY's writeup is being ignored?


Sundance 6G72 - If your seeing accurate timing from the MS, i seriously doubt you have anything to worry about

The point of this thread is to get after the reasoning for running certain settings, not "everything seems fine." Why exactly are/were people (Ed, Nathan, others) deviating from the suggestions of DIY when setting things up on the low data rate 12v distributor. I would be interested to see the same cars running as suggested and compare datalogs. My car does not run at the moment but I would not mind trying both ways if it is running.

I think there is also a statement from Nathan that I read once where he said his timing advance was capped at 37 degrees "physically" but then I see his trigger angle setting is 11 degrees different then what Ed was running or what Joe is running now. How was that limitation determined and heck, I know I can run more then 37 on a stock computer. Ed has been modifying ignition rotors in the past, trimming them down creating a smaller window of timing potential but preventing crossfire. There are or were a lot of out of the box methods going on so I am looking for the science behind it all.
--------------------------------------
http://www.diyautotune.com/tech_articles/how_to_megasquirt_your_mitsubishi_mopar_30_sohc.ht m
"MegaTune Configuration for MS-II

Set ignition capture to "Falling Edge," and coil charging to Standard Coil Charging. Dwell will depend on exactly which coil you are using. Cranking trigger time must be set to Calculated. If using MS2/Extra, set the ignition type to Basic Trigger.

Important when using the BIP373: On the 'Ignition Settings' menu make sure to set 'Spark Output' to 'Going High (Inverted)' and set 'Coil Charging Scheme' to 'Standard Coil Charge'."
--------------------------------------

[c2xejk]

For the record, I currently have ignition capture set to "Falling Edge".

[Shadow24]

IIRC, nathans "ignition breakup" at higher RPMs was due to lifter collapse... I don't remember if there was any issues with total advance, but I don't think there was any physical limitations then.

[nmw2006]

My original breakup problems were actually lifter collapse caused my running too light of oil (0w20). After beating my head on a wall on that one, I still could not get more than 37* of demanded timing no matter what I did. This does equal 49* when including base. After that point it didn't matter what position the distributor was in, after accounting for the rotational movement with trigger angle, I could not go beyond 37* without high rpm (6500+) breakup.

I was researching trigger angle and found this via Matt Cramer @ DIYAutotune.


Trigger angle is the angle before TDC where the Megasquirt "thinks" it's getting a signal from the CAS. If you have a trigger angle of 60 degrees and a spark advance of 20 degrees, for example, the Megasquirt waits for a signal from the CAS, then counts down the amount of time at your RPM it would take to turn 40 degrees, then commands it to fire a spark. If the CAS signal actually came in 65 degrees BTDC instead of 60 degrees BTDC, the spark would happen at 25 degrees when the Megasquirt "thinks" it's happening at 20.

So the goal there is to make the physical trigger angle match the angle that the Megasquirt is using to calculate its ignition timing.

This means trigger angle has to be calculated for each motor setup. I was using this when messing with my distributor. As a test, I tried rotating it both directions (between the factory stops) which would throw off my base timing. I adjusted for this in my tables and with trigger angle. This is why my trigger angle was different than other peoples.

After all this I still never figured it out and pretty much gave up on revving it that high. I'm probably missing something here so feel free to call out what I was doing wrong. :)

- - - Updated - - -


Ed has been modifying ignition rotors in the past, trimming them down creating a smaller window of timing potential but preventing crossfire.

This interests me as I was actually wondering if this was happening to me. This is what I meant when I said "physically" limited.

[Ondonti]

My original breakup problems were actually lifter collapse caused my running too light of oil (0w20). After beating my head on a wall on that one, I still could not get more than 37* of demanded timing no matter what I did. This does equal 49* when including base. After that point it didn't matter what position the distributor was in, after accounting for the rotational movement with trigger angle, I could not go beyond 37* without high rpm (6500+) breakup.

I was researching trigger angle and found this via Matt Cramer @ DIYAutotune.



This means trigger angle has to be calculated for each motor setup. I was using this when messing with my distributor. As a test, I tried rotating it both directions (between the factory stops) which would throw off my base timing. I adjusted for this in my tables and with trigger angle. This is why my trigger angle was different than other peoples.

After all this I still never figured it out and pretty much gave up on revving it that high. I'm probably missing something here so feel free to call out what I was doing wrong. :)

- - - Updated - - -



This interests me as I was actually wondering if this was happening to me. This is what I meant when I said "physically" limited.

I have 0 for trigger angle with falling edge because that always functioned in the past. Basically what you first attempted to run long ago. That did work for me at the time.

What method is used to check base mechanical timing without getting electronic advance in there messing up results? I had set mine up with OEM computer then did MS so I never dealt with it.

[Shadow24]

I have 0 for trigger angle with falling edge because that always functioned in the past. Basically what you first attempted to run long ago. That did work for me at the time.

What method is used to check base mechanical timing without getting electronic advance in there messing up results? I had set mine up with OEM computer then did MS so I never dealt with it.

MS has a "fixed timing" option used to zero in trigger angle and can also be used to set the base timing. it sets the timing at a fixed value and keeps it there until you disable it. you could set it at 0* and see where your timing light shows up at, and adjust the base distributor timing from there. Then once disabled, you would have base + ignition table for advance.

[Sundance 6g72]

I dont even know why I have certain things set the way they are to be honest. I dont think I even followed the DIY article either, I just went for it.

[Ondonti]

MS has a "fixed timing" option used to zero in trigger angle and can also be used to set the base timing. it sets the timing at a fixed value and keeps it there until you disable it. you could set it at 0* and see where your timing light shows up at, and adjust the base distributor timing from there. Then once disabled, you would have base + ignition table for advance.
So if I have 12 degrees base during fixed timing I would use +12 degrees in my offset. Then my timing maps would all be short 12 degrees since I wrote them up with the 12 degrees subtracted.

[Sundance 6g72]

just set it to fixed 12 or 10 or 8 or whatever you want.

then get out the light and check and see where it is on the timing bracket thing by the crank pully. adjust the dizzy or your trigger offset until the light reads 10* (or whatever MS is fixed to)


done

[Ondonti]

So my offset had to be set at 15 degrees. After 9 degrees of offset (fixed was set at 10) it started increasing the value that I was trying to match up with. So I had to match to 16 degrees (was fixed 10) and ended up with 15 degrees of positive offset. I tried moving my distributor counterclockwise but that seemed to make timing bounce around.

So now I am running truely off my table.

[Ondonti]

I was pointed towards this link by a Mod on MSextra.com Apparently MS3 explains basic trigger better then any older stuff did.

http://www.msextra.com/doc/ms3/distributor.html

This is what 87turbodance was doing with his settings in http://www.turbo-mopar.com/forums/showthread.php?58964-My-3-0-Megasquirt-install-guide!&highlight=rising+edge
but neither explains the "why" of many actions involved in this style of setting base timing (like why you want offset to be in a certain range, or why you are following such and such procedure.).

I did find that when my distributor was turned too far counterclockwise I had erratic timing (and probably crossfiring).

[87turbodance]

With the stock dist you can never achieve the ideal trigger angle without moving the dist out of sync with the coil towers. crank trigger solved this for me. symptoms are breakup at high advance values.

Trigger angles that will get you a running motor wont allow for more then about 34-40 degrees advance before running out of time (literally). the trigger angle must occur with enough time tdc to allow Ms to calculate the advance. MS calculated advance based on time when using a dist. crank trigger uses a combo of crank teeth ---- and time, MS3 uses purely counting crank teeeth.

[Ondonti]

Looking at the same datalog above, I charted out

Spark Advance
Base Spark Advance
Spark Table 1
Idle corrective advance

And realized that with my base timing set at 15 degrees offset, megasquirt is unable to achieve anything less then 16 degrees advanced. This makes tuning idle not as easy and also creates a problem for boost because my planned timing table at low rpms requires less than 16 degrees of timing once it gets around 7psi boost (150kpa) and around 3000 rpms. That timing stays very low until 4500 and then ramps up quickly. 3000 rpms won't be a problem because I would never get much more then 7psi with a large cam installed but 3500-4500 will be a problem as boost ramps up and peaks in that range with the turbo I will again be using in the future. When I set base timing it was happiest at 15 degrees of offset. Now I need to see how far I can reduce the offset. Maybe it will behave better with the tune a bit more dialed in.

Originally in 2010 I had zero offset, my base timing adjustment had been set with an OEM ecu at 12 degrees stock. I then just decided I would subtract 12 degrees from my actual timing map. At this point I have no idea what was going on with my "real" total spark timing then but reported spark values were able to go to zero and over 40 degrees. I hear we only have around 40 degrees of spark adjustment with our distributor so I don't know why I would want 16 to 56 when most of the upper range is unusable...The old firmware datalogs do not have as much information to sift through.

I don't exactly understand why Megasquirt won't allow you to have your timing less than the offset. Now I have to research :P

Messing with something once a year or less makes it hard to remember what exactly is going on with our ignition sync.

[87turbodance]

I don't exactly understand why Megasquirt won't allow you to have your timing less than the offset. Now I have to research :P

Messing with something once a year or less makes it hard to remember what exactly is going on with our ignition sync.

Megasquirt 1 and 2 use calculated periods of time to guestimate spark advance. Megasquirt bases all advance off of a reference point which is your trigger angle. Megasquirt will then calculate how much time to wait past the trigger angle to fire the spark. It cannot fire a spark before the trigger angle because of this fact. The stock distributor acts as a 6 tooth wheel run at crank speed.

If you want to simply things immensely, drill 6 evenly spaced holes in the outside of your damper 60 degrees apart with the first one aligning with a hall sensor when the crank is at 60 degrees btdc on any cylinder. Thread the holes and install 6 1/4" ferrous metals studs/bolts in the damper. Don't forget to loctite them

Configure MS for 6 toothed wheel with a trigger angle of 60 degrees

Then transfer the distributor wiring to the hall sensor and continue to use the distributor but let the crank sensor do all the timing work. Just adjust your distributor however you want to achieve the best spark range. ie set it up so that the rotor is close to the correct spark tower with a crank angle range of 50 to +10 degrees or whatever works out. When you have the distributor timing and the timing pickup separated it makes things soo much easier.

In my experience I could achieve a 60 degree spark angle range without cross talk in the distributor cap. Based on some quick math, I believe you will need to go wasted spark if you need range larger then 60 degrees because of limitation with using a distributor cap.

Bottom line, when you separate the distributor cap from the MS trigger input angle you gain the freedom to choose an ideal trigger angle and an ideal distributor cap position without making sacrifices. With the stock setup and MS you have to sacrifice one or the other to achieve something that works because both are tied together in the same component - you turn one and the other turns too.

[Ondonti]

Megasquirt 1 and 2 use calculated periods of time to guestimate spark advance. Megasquirt bases all advance off of a reference point which is your trigger angle. Megasquirt will then calculate how much time to wait past the trigger angle to fire the spark. It cannot fire a spark before the trigger angle because of this fact. The stock distributor acts as a 6 tooth wheel run at crank speed.

If you want to simply things immensely, drill 6 evenly spaced holes in the outside of your damper 60 degrees apart with the first one aligning with a hall sensor when the crank is at 60 degrees btdc on any cylinder. Thread the holes and install 6 1/4" ferrous metals studs/bolts in the damper. Don't forget to loctite them

Configure MS for 6 toothed wheel with a trigger angle of 60 degrees

Then transfer the distributor wiring to the hall sensor and continue to use the distributor but let the crank sensor do all the timing work. Just adjust your distributor however you want to achieve the best spark range. ie set it up so that the rotor is close to the correct spark tower with a crank angle range of 50 to +10 degrees or whatever works out. When you have the distributor timing and the timing pickup separated it makes things soo much easier.

In my experience I could achieve a 60 degree spark angle range without cross talk in the distributor cap. Based on some quick math, I believe you will need to go wasted spark if you need range larger then 60 degrees because of limitation with using a distributor cap.

Bottom line, when you separate the distributor cap from the MS trigger input angle you gain the freedom to choose an ideal trigger angle and an ideal distributor cap position without making sacrifices. With the stock setup and MS you have to sacrifice one or the other to achieve something that works because both are tied together in the same component - you turn one and the other turns too.

What was the timing adjustment window that you found when doing the falling edge method at 75 deg BTDC?

I am not looking for high timing, but low timing.

BTW, until I found out today about "This cylinder" or "Next cylinder" modes, a lot of this didn't make sense. Anything at low BTDC angles means it has to skip to the next cylinder and for some reason the code won't allow firing before the offset degree even though you are waiting for the next cylinder.

Offset angle of 60-90 allows "this cylinder" ignition and will basically fire any angle the rotor in your distributor is compatible with on the correct cylinder. That means I have to verify the rotor lines up in my planned timing window as you suggest in your writeup.

What about trigger return setup? That sounds like the best of both worlds using the OEM distributor.

BTW, it seems like I need to throw my degree wheel on the crank to really do what they want but then they also suggest "guessing" :P

[87turbodance]

I've tried all the settings and distributor positions I could never get what I wanted. I even tried to reclock the rotor to achieve a better rotor to sensor alignment. Finally I said ---- it and added a crank sensor; best thing I ever did.

[Ondonti]

I've tried all the settings and distributor positions I could never get what I wanted. I even tried to reclock the rotor to achieve a better rotor to sensor alignment. Finally I said ---- it and added a crank sensor; best thing I ever did.

I would be happy with -5 to 35 degrees or 0 to 40 degrees BTDC as a working range. I really have no need for high timing numbers once boost is involved.

What ranges did you actually achieve? I know you wanted more then was possible.

[87turbodance]

I would be happy with -5 to 35 degrees or 0 to 40 degrees BTDC as a working range. I really have no need for high timing numbers once boost is involved.

What ranges did you actually achieve? I know you wanted more then was possible.

Unfortunately, it's been a couple years so I can't remember. You'll have to get out the degree wheel, mark the spark tower positions on the distributor and mess around with MS and your distributor position until you find something that works. I was using MS1 which is a real pain for this stuff. MS2 is better so you might have more luck.

I honestly think you'll spend less time adding a crank sensor... You could probably get away with only adding three "teeth" to your crank pulley which would give you the same resolution as the stock distributor but with the freedom to choose your trigger angle. Six teeth will give better starting performance, though.

[Ondonti]

Unfortunately, it's been a couple years so I can't remember. You'll have to get out the degree wheel, mark the spark tower positions on the distributor and mess around with MS and your distributor position until you find something that works. I was using MS1 which is a real pain for this stuff. MS2 is better so you might have more luck.

I honestly think you'll spend less time adding a crank sensor... You could probably get away with only adding three "teeth" to your crank pulley which would give you the same resolution as the stock distributor but with the freedom to choose your trigger angle. Six teeth will give better starting performance, though.
BTW, is there a good way to make the cam signal useful in sequential setup?
I will definitely mess with the degree wheel because I will at least get a better idea of what is going on. I don't mind spinning my wheels on some of this stuff as its helpful for others.

[87turbodance]

BTW, is there a good way to make the cam signal useful in sequential setup?
I will definitely mess with the degree wheel because I will at least get a better idea of what is going on. I don't mind spinning my wheels on some of this stuff as its helpful for others.

You can block off all the openings in the high res section of the shutter wheel and then use a sharp knife to cut out one section in the spot you want the cam pulse to be. You could also do the same thing with the low res area of the wheel but then you won't be able to use it as a crank trigger anymore.

If it was me, I'd use a crank sensor and then use some foil tape to block off all but one cut out in the low res shutter wheel to use as a cam sensor.

[crusty shadow]

if I were you I would add a 36-1 wheel on the crank, then do a half moon shutter wheel on the distributor. best possible signal setup for MS- no limitations on timing. I made a jig for the 36-1 wheel to align it with the crank pulley and welded it on- worked perfectly and was not hard to do. for the half moon cam shutter wheel I just took a N/A distributor and cut all the teeth off the shutter wheel, made a half moon shutter wheel out of a 2" exhaust pipe connector that I bought from Autozone PN 17504 cut it to size with a chop saw and welded it to the original shutter wheel base. that was also pretty easy.



the end result is nearly instant sync as soon as you hit the key, and the most accurate timing setup you can get

http://i48.photobucket.com/albums/f237/crusty_shadow/triggersync1_zps45736753.png (http://s48.photobucket.com/user/crusty_shadow/media/triggersync1_zps45736753.png.html)

[Ondonti]

I would not attempt to use two sensors at the same time from the distributor. If I wanted to be that accurate I would want to take out the timing belt deflection from the equation.

[87turbodance]

Well, you could easily convert the distributor pickup to the half moon style mentioned above. Then add some manor of crank position sensor. A 36 tooth wheel is overkill for ms2 but can be bought off a shelf but as I've mentioned i found it super easy to mark up my damper with some ink and a scriber and a drill press. A 6 or 12 tooth wheel would work great a six cylinder without putting much effort into it. i used a piece of angle aluminim to mount a crank sensor towards the front of the motor under the distributor. I found that a hall effect cam sensor from a 2000ish madza 2.0 worked great as a low resolution crank sensor; salvage yard parts work great for mockup and testing. The half moon distributor and a 12 tooth crank gives all you need for a great wasted spark setup..... or just run the crank sensor and the distributor/single coil.

[Ondonti]

Well, you could easily convert the distributor pickup to the half moon style mentioned above. Then add some manor of crank position sensor. A 36 tooth wheel is overkill for ms2 but can be bought off a shelf but as I've mentioned i found it super easy to mark up my damper with some ink and a scriber and a drill press. A 6 or 12 tooth wheel would work great a six cylinder without putting much effort into it. i used a piece of angle aluminim to mount a crank sensor towards the front of the motor under the distributor. I found that a hall effect cam sensor from a 2000ish madza 2.0 worked great as a low resolution crank sensor; salvage yard parts work great for mockup and testing. The half moon distributor and a 12 tooth crank gives all you need for a great wasted spark setup..... or just run the crank sensor and the distributor/single coil.

I found today that my setup as is was able to physically spark farther then -10 ATDC timing and ~50 degrees BTDC.
Now I am going to mess around with adjusting things. I don't know if it was the reasoning behind your original plan to run trigger return but that suggested setup of yours is supposed to provide the good starting of cam phasing around 5-15 degrees BTDC and have the good running and adjustability of setting it between 60-90 BTDC.

I only see upgrading from camshaft only to include all the mods required to run sequential fuel injection and coil on plug ignition. I really don't think I have the ability around here to get a spark tune close enough to need greater accuracy without spending the money that would make a weaker ignition setup pointless. So I think if I get stuck someday with ignition blowout (especially caused by high rpms) then I will then move to upgrade my Tach In setup.
My distributor setup right now really kills off my dwell time at higher rpms. Not sure what rpm it will have problems at without boost but I have a feeling that boost + 8500 rpms (goal) will not work. I will probably try boost a coil first and run the coil at higher voltage when I get there before upgrading the entire ignition system. I think I would also give a hotter coil a chance.
3000gt guys have problems with their wasted spark blowing out in many 500+whp setups but its hard to say how good of a job they are doing to minimize problems on the setups in the lower range of HP. I had to use small spark plug gaps with OEM ignition and then had to go even smaller as HP rose. Alcohol injection also makes spark blowout happen at even lower HP levels. Spraying 3 nozzles makes it really bad.

[Ondonti]

I really failed at this.


Pretty sure there is a typo for falling edge instructions from 87turbodance but...
I was lazy so I only put my degree wheel on and set it to zero based on the camshaft arrow to timing cover mark.
================================================== ===========================================
Then I put the crankshaft to 10 degrees BTDC

Forced to enter trigger return spark mode and enter an offset higher then 60 or it caused configuration errors in ms2/extra 3.3.1, Set offset to 75

Falling edge

Set middle LED indicator to Ignition trigger indicator
---------------------
Now, turned back distributor backwards until LED turned off. Slowly turned forward until it turned on. Its almost exactly where it was when I used a 15 degree offset and a timing light to set things up with basic trigger. Locked down the distributor.
-----------

Set fixed cranking timing to 10
Set fixed timing to 10
Left predictive timing on.

Verified rotor was just about to leave #1 terminal at 10 degrees BTDC
-----------------------------
Left in trigger return mode and falling edge
Tried to start and got a few nasty backfires. Tried again and it started.
================================================== ===========================================
Megasquirt is commanding 10 degrees timing BUT my timing light indicates something like 30 degrees ATDC (retarded).

Should have taken a datalog.
Seems like a big failure.

[Ondonti]

Here is the only description I have read of trigger setup that has actually been clearly explained.


This refers to setting up an Audi distributor but its basically the same as the 3.0 12 valve SOHC distributor except the inner optical data is from 5 small and 1 large window slots while 3.0 6g72 12 valve is 6 equally spaced large slots. Both have outer 360-10 slots.
Looking into this also lead me to the Nissan CAS which has replacement distributor (50 and 54mm) slotted discs available on DIY's website that are megasquirt compatible with full sequential. I might try one of these in the future. I don't think the ECU can handle our high data 360-10 slot setup. I did think that we could just cut out groups of slots in the OEM and create a 36-1 wheel. I did not measure our OEM wheel to see if its 50 or 54mm. They mention possible compatibility with Mitsubishi applications.
http://www.theprojectpad.com/viewtopic.php?f=14&t=796



Re: Anyone else running MegaSquirt?

Postby vt10vt » Tue Jun 24, 2014 12:04 am
MS1/2/3 this doesn't matter. I'm on MS2, ran the same setup on MS1. It's all the same except that MS1 uses trigger angle additions but that's not relevant here or to most anyone so I'm not even going to get into it.

I'll give you the long of it, if you want the short of it skip to the end for the easy/copy cat answer. But that's not what some of us are about is it? ;)

By setting your trigger angle you are telling the ECU the relationship between when it sees events from the hall effect sensor in the distributor and the rotor being "centered" on the post for the respective cylinder you are firing.

The first thing is that the trigger angle requirements are determined primarily by the processor speed and by the desired range of advance. So if you had an ECU that could do calculations at the speed of light and wanted a maximum advance of 40* Before Top Dead Center (BTDC) then your trigger angle could be only 40*. But math takes time (especially for me ;) ) so you need some space and time built in there for Megasquirt to do it out.


*ASIDE/IGNORE* VEMS still needs the same minimum trigger angle (---- whatever VEMS calls it, it's Megasquirt based and you know it; it's a trigger angle). I don't know if it's processor limited or not, you wouldn't think so because it can read fast enough to keep up with a 135 tooth flywheel but I'm not sure.


So if you were to set your trigger angle at, say, 60* in TunerStudio, you are telling Megasquirt that when it sees a pulse from the hall sensor it is 60* from the next time the distributor rotor is centered on a post. Couple important things to remember here are that in basic trigger mode like you're running Megasquirt has no idea which cylinder it is actually firing, all it knows is that 60* from when it sees that pulse the rotor will be centered on a post. The rotor making contact with the distributor cap is the only thing that dictates which cylinder the coil ignites. Second is that with the motor set at TDC the rotor is centered on the distributor post for cylinder number one. In reality you don't really want the rotor centered on the post at TDC but we'll get to that in a minute. Third is that you are primarily dealing with the relationship between the sensor and the windows in the distributor. The position of the engine does come into play but trigger angle is primarily the relationship between the sensor and windows.

Megasquirt will then make calculations based on the current engine speed to tell how long it will take for that 60* to happen, and based on that time calculation it can adjust timing. Using arbitrary numbers for example's sake, if you're at idle and the hall sensor is moving 60* every 6 milliseconds, and you want the cylinders firing 10* BTDC the ECU would calculate the distributor is moving 10*/1millisecond based on the speed it is seeing events from the hall sensor and would fire 5 milliseconds after the pulse from the hall sensor comes. Thus the rotor would have moved 50* in that 5 milliseconds igniting your cylinder 10*BTDC. So if you commanded 0* advance at the same RPM Megasquirt would wait 6ms after it sees the pulse from the hall because in that 6ms the rotor would have moved 60* and thus be firing directly in the center of the rotor, which means our engine would be at TDC. Remember that when set at TDC our theoretical engine will have the rotor centered on the post attached to cylinder 1. Thus when cylinder 2 is set at it's "TDC" the next window will have sent it's pulse 60* and 6 milliseconds ago giving Megasquirt that 6milliseconds advance warning to calculate how fast the engine and thus the rotor are moving, time out dwell and then fire at whatever angle.

So hopefully what the trigger angle is doing makes sense, if not go read the megamanual front to back again a few times haha. Now on to where to set it.

This is where the theoretical engine needs real world tweaks. If you look at a spark map, you generally run 10-50 degrees of spark advance (ie degrees BTDC/Before Top Dead Center) depending on RPM, manifold pressure, temperature etc. The angular relationship between the rotor and points is the limiting factor here. Look the outer circumference of the rotor edge in relation to the entire 360* of the distributor and you'll see it only makes up a fraction of that total 360* of rotation. The size of the rotor edge dictates available engine advance. Thus the angle of the rotor on the point for cylinder #1 with the engine at TDC needs to be adjusted to compensate for the degrees of timing you actually want to run. About -19* is the angle the megamanual recommends for this ("-" =BTDC). The closest your timing will get to TDC is usually at idle, so 10-15* BTDC meaning you need to offset your rotor to allow for more BTDC timing because you won't use much (any?) positive timing. So with the engine set at TDC, your distributor rotor should actually be 19*BTDC or 19* counter clockwise prior to the actual center of the rotor.

So the process would be set the engine at TDC/Top Dead Center, center the rotor on the point for cylinder #1, then rotate the distributor housing counter clockwise (against it's running rotation) 38* to "center" the rotor relative to the angles of desired spark advance while allowing the shaft and rotor to stay in the same position. Then you would turn the engine backwards and measure the angle it takes to trigger the hall sensor. However, what you will end up with is actually in the unacceptable range, so you need to go back an extra window. Megasquirt needs either 0-5* or 60*+ and the OEM Audi distributor will fall in the range of 5-59* which won't work. So if you just keep going backwards to the next window you end up with a very high angle. In MS1 this is dealt with via trigger angle additions but in MS2/3 it's straight up trigger angle.

So set the engine to TDC. Center the rotor on the point for cylinder #1. Turn the distributor housing counter clockwise ~19*. Then turn the engine counter clockwise until a vane is at the sensor. This will be between 5 and 59* which won't work. Keep rotating backwards until you're at the edge of the next vane. Remember, the ECU only knows what you tell it so if you say 115* it knows to start calculating for the rotor it will see 115* after it sees the hall pulse, it doesn't matter if it sees another pulse/vane before it fires from the last one it saw. Overlap doesn't matter. This will work but your angle will be very high somewhere between 110* and 120* which is fine. This is where trigger angle additions come into play with MS1 but you don't have to deal with this. So that angle you measured is your trigger angle. Bam. Done. Wasn't that easy? :) Now you just need to use either the timing wizard in tuner studio or manually set the spark angle and use a timing light to dial in your timing exactly which can be done either by rotating the distributor or by changing your trigger angle. I recommend rotating the distributor with the engine running and a timing light on the flywheel with the timing locked at 10*BTDC in tuner studio and an adjustable timing light set to the same 10*.

And something that bothers me with what I am doing right now,


Also you dont need to be running trigger return, that setting determines which edge of the distributor sensor the ecu uses during cranking. I dont remember which I'm using atm but it only relates to trigger angle in that your trigger angle will dictate if you can run one or the other or both interchangeably.


Guy who is said to be THE Audi megasquirt guy with additional electrical engineering background


You want "basic trigger" mode. Trigger-return is evil... it does a lot of weird things, like trigger on one edge while cranking then the other when running.


Trigger return is supposed to be good in that it allows you do use one side of the slot for cranking and another slot for running. That avoids the tradeoff where trigger angles of 0-5 degrees BTC only provides high quality starting and 60-90 provides the best running characteristics.

This might be why so many people were running rising edge instead of falling edge...So the 3.0 megasquirt install guide by 87turbodance still does not make sense for rising vs falling edge. I know Kyles MS3 functions with 75 offset, his distributor alignment looks the same as mine, and he uses falling edge and trigger return. Mine does not work as is.

I need to go record what angles the Middle LED trigger indicator turns on and off at in the 0-100 BTDC range. Then figure out if I can use trigger return or if I have to use basic trigger and also figure out if I need to use rising edge instead of falling. Having had apart my messed up optical setup in my He341 3.0 Spirit, I know there is some adjustability in the slotted disc and also the rotor if I really needed to. I could force more adjustability in worst case scenario.

[Ondonti]

With distributor setup to be about "normal" compared to 2 other 3.0s,
--------------------------------
Trigger turns on with falling edge trigger return

ON 130 to 75 BTDC

Off 75-10 BTDC

ON 10 BTDC - 45 ATDC

---------------------------
So I think I need to use rising edge since the setup instructions want your LED to turn "on" during the 75-10 window, not off.

[Ondonti]

This is kinda making me grumpy with megasquirt even more since the best descriptions date back to MS1 stuff and it seems that people are given less and less "why" along with the newer stuff, even when the same circuitry is used.

http://i546.photobucket.com/albums/hh426/ondonti/Megasquirt/Megasquirt%20II%20Extra%20Circuits/Mitsubishi6g72SOHC12valve30DistributorOpticalSenso r.png (http://s546.photobucket.com/user/ondonti/media/Megasquirt/Megasquirt%20II%20Extra%20Circuits/Mitsubishi6g72SOHC12valve30DistributorOpticalSenso r.png.html)

http://www.msextra.com/doc/ms1extra/Dizzy_Ignition/LED_for_IRQ.htm



You can monitor and test the Optical or Hall input for proper operation by setting the center LED on the MegaSquirt front panel to show the state of the IRQ-1 inside MegaSquirt.

First set up TunerStudio to help you time the distributor. Set the center LED on the MegaSquirt front panel to show the state of the IRQ-1. These settings will be under Menu Basic Settings > Codebase and outputs Function.

To do this set Distributor to MSnS^ LED 19(D16) to IRQ trigger. This LED is usually set to Warm Up. Click on Send to ECU. Here is a subset of the settings in the dialog box.


Center LED indicates the state of the Trigger

LED is OFF; MS opto-isolator is off, IRQ-1 is high.
LED is ON; MS opto-isolator is on, IRQ-1 is low.
LED transitions from Off to On, this is the Trigger Angle at the crank.
LED transitions from On to Off, this is the Trigger Return Angle at the crank.

[87turbodance]

You can setup MS to "trigger" on either the slots on the pickup wheel or the filled in parts of the trigger wheel. The trigger angle will be the beginning of the opening or gap and the trigger return will be either the ending of the opening or gap. Try to get the of transitions of the beginning or ending of the gap to line up with about 0 degrees btdc - this will make a great trigger return angle for starting. Then rotate the motor backwards until the middle LED changes to indicate that you have reached the other end of the opening or gap - this will become your trigger angle. Then get your spark tower terminals to line up with the trigger range you've setup.

[Ondonti]

I have to change my chart now to reflect that those #'s were taken with falling edge and maybe make another showing rising edge. I changed the setting to rising edge and then my 10-75 degree BTDC window is ON instead of off. Falling edge vs rising edge just changes weather megasquirt is looking for voltage to be high or pulled low so changing the setting will "flip" the range that is considered "ON"

Now timing sets at 10 degrees with a slight distributor adjustment (could have used trigger wizard and changed my crank offset).

Very happy.

Then took a datalog of some 4th of July antilag afterfires.

My timing is now able to go to -10 degrees during antilag :D (when not cutting sparks). Idle timing control is now also able to go below 16 degrees (previous limit with basic trigger settings at 15 degrees offset) so my idle is very happy.