PDA

View Full Version : LM boost control v. boost spike problem



tryingbe
11-24-2011, 09:42 PM
Swirl 782 head with 2.5L running LM V12.5 cal. Using 87 TII vacuum map setup to the, vacuum line from source, to the solenoid, to the actuator is less than 1 ft. Not using any orifice

Boost is set at 13psi via boostvspeed I'm experiencing boost spike to 17psi at initial spool up, rpm is less than 3000rpm when it happens. Boost would settle down quickly and it would go to the predefine setting all the way to redline.



Only setting I've change so far is lower than MinimumRpmToTrackBoostCreep to 1220rpm, doesn't seems to help.


Any idea which table I need to change to try the reduce my boost spike?

Aries_Turbo
11-25-2011, 12:09 AM
BoostWotDutyCycle and BoostWotDutyCycleAdj

since you dont have the exact same setup as stock (ie no restrictor) BoostWotDutyCycle is going to have to be retuned to the new setup.

whatever your BoostAllowed tables are set to, you have to adjust the values in BoostWotDutyCycle so that you dont get spikes or lagginess.

i think there are adaptive values for the boost control too so you can see how far off you are. Unfortunately, ive never datalogged them so i dont know exactly what to do to determine what they are. Rob would know though.

Brian

tryingbe
11-25-2011, 09:27 AM
Are FullThrottleWastegateDuryCycle C8is100Percent FromMap and FullThrottleWastegateDutyCycleAdjustment FromRpm the same values as the one you're talking about?

ShelGame
11-25-2011, 09:52 AM
Yes, those are the 2 main DC tables. It's a tough call without the restrictor, but my guess is that you'll want to increase the slope of the line (ie move it toward horizantal, not vertical) going up to your max boost. Also, make sure that the last point goes out at least to your max boost setting. I would probably go a couple psi higher. Since your close to stock boost and still getting spikes, I would probably increase the DC near your max boost. That should slow it down.

Aries_Turbo
11-25-2011, 10:56 AM
rob, are there adaptives in the LM stuff for the boost control like i see on your MPScan SMEC setup file?

i loaded a list file and the premade LM MPScan setup file and i didnt see anything like the SMEC has for boost control adaptives.

Brian

ShelGame
11-25-2011, 05:25 PM
rob, are there adaptives in the LM stuff for the boost control like i see on your MPScan SMEC setup file?

i loaded a list file and the premade LM MPScan setup file and i didnt see anything like the SMEC has for boost control adaptives.

Brian

I'm pretty sure there are, but I never really looked to be honest. The pre-made MP Scan files don't have everything in them. Just the basics...

Aries_Turbo
11-25-2011, 11:24 PM
yeah i knew the premade ones didnt include everything, but i figured the list file would.

Brian

tryingbe
11-26-2011, 10:46 PM
Yes, those are the 2 main DC tables. It's a tough call without the restrictor, but my guess is that you'll want to increase the slope of the line (ie move it toward horizantal, not vertical) going up to your max boost. Also, make sure that the last point goes out at least to your max boost setting. I would probably go a couple psi higher. Since your close to stock boost and still getting spikes, I would probably increase the DC near your max boost. That should slow it down.

I thought without the restrictor will give me LESS spike? I can't imagine having the restrictor on now, it'll probably want to go to 25psi on the spike.

But I'm not having trouble with my max boost. I'm having trouble with boost control at my initial spool up. Currently I have it set as 12psi to 16psi depends on my speed. When I get on it on 2nd gear, turbo will spool to 20psi, then come down to 14psi to then go back up to 15psi at the end of 2nd gear. What do I need to do to so I will not have to boost spike at the initial spool up on the turbo?

http://www.thelostartof.net/tryingbe/dodge/omniproject/boost.JPG


I tried to adjust to this, no difference.
http://www.thelostartof.net/tryingbe/dodge/omniproject/duty.JPG

Any picture of how I should adjust the line? I'm not good trying to convert your words into graph. Thanks.

Force Fed Mopar
11-26-2011, 11:22 PM
Here's what I have mine set at in my T-LM cal for my 2.2 Daytona w/ a heavily shimmed small can wga. I have my target boost set at 17 psi, it spikes to 19 on initial spoolup, then drops down to 17 as the engine revs back towards redline.

FYI the boost control did not work right at all until I made the last point drop to near 29 psi (3-bar)

tryingbe
11-27-2011, 12:01 AM
Force Fed Mopar,

Would you make the SHOW HEX tables on the right side a little bigger so I can see your X and Y point numbers? Thanks.

Force Fed Mopar
11-27-2011, 12:05 AM
Should be able to click the pic twice and make it larger? I'll see what I can do...

Force Fed Mopar
11-27-2011, 12:16 AM
Try this, you should be able to read the names if you mouse over them but the first is the FullThrottleWastegateDutyCycleAdjustmentFromRPM, the second is the FullthrottleWastegateDutyCycle.

tryingbe
11-27-2011, 11:18 PM
Your settings didn't help me. I'm gonna try something else and report back.

Force Fed Mopar
11-28-2011, 02:11 AM
Are you running a Garrett or Mitsu?

tryingbe
11-28-2011, 09:30 AM
Custom T04E/T3 Garrett.

tryingbe
11-28-2011, 08:50 PM
Alright, this didn't do anything. Trying something else.

http://www.thelostartof.net/tryingbe/dodge/omniproject/boost1.JPG

tryingbe
12-01-2011, 11:21 PM
This seems to do the trick.

http://www.thelostartof.net/tryingbe/dodge/omniproject/tune/booost.JPG

Force Fed Mopar
12-02-2011, 10:30 AM
Hmm, odd...

tryingbe
12-02-2011, 10:34 AM
Still spikes, but it spike to 14psi and kept at 12psi instead of spiking to 20psi.

ShelGame
12-02-2011, 11:06 AM
Alright, this didn't do anything. Trying something else.

http://www.thelostartof.net/tryingbe/dodge/omniproject/boost1.JPG

What does the table immediately above this one look like?

---------- Post added at 10:06 AM ---------- Previous post was at 10:05 AM ----------


This seems to do the trick.

http://www.thelostartof.net/tryingbe/dodge/omniproject/tune/booost.JPG

Well, since your boost target below ~40mph is actually only about 8psi, I'd say you're still spiking if you hit 14 on spool up...

roachjuice
12-02-2011, 12:12 PM
Manual boost controller. /thread.

wowzer
12-02-2011, 02:18 PM
fwiw - i noticed rob M that on the first table you posted that the x axis rpm goes to 16384. i'm guessing that the upper limit should really be 8192 so that might need to be changed. rob L will have to chime in on that.

Force Fed Mopar
12-02-2011, 04:56 PM
Well, since your boost target below ~40mph is actually only about 8psi, I'd say you're still spiking if you hit 14 on spool up...

That's what I was thinking.

---------- Post added at 03:56 PM ---------- Previous post was at 03:52 PM ----------


fwiw - i noticed rob M that on the first table you posted that the x axis rpm goes to 16384. i'm guessing that the upper limit should really be 8192 so that might need to be changed. rob L will have to chime in on that.

Wonder if that makes a difference?

ShelGame
12-02-2011, 05:37 PM
That's what I was thinking.

---------- Post added at 03:56 PM ---------- Previous post was at 03:52 PM ----------



Wonder if that makes a difference?

It's just a scaling factor. It won't affect the cal, per se. I'd have to check if it's correct. Sometimes the LM uses that scale, others it uses the 8192 scale...

wowzer
12-03-2011, 12:52 AM
It's just a scaling factor. It won't affect the cal, per se. I'd have to check if it's correct. Sometimes the LM uses that scale, others it uses the 8192 scale...

ya, i noticed there were several tables that go to 16384. i guess my point was it only affects the cal if the scale is wrong and the user "adjusts" the points to reflect the desired rpm.

tryingbe
12-03-2011, 09:40 AM
What does the table immediately above this one look like?

---------- Post added at 10:06 AM ---------- Previous post was at 10:05 AM ----------



Well, since your boost target below ~40mph is actually only about 8psi, I'd say you're still spiking if you hit 14 on spool up...

I know it's still consider "spike", but at least it's on a manageable level instead of spiking to 20psi. NO issue with part throttle boost, it goes to where I set it and stays there!

Left it at stock. Since I really have no idea what I was doing. I tried to just change 1 table instead of 2.

http://www.thelostartof.net/tryingbe/dodge/omniproject/tune/boostdc.JPG


Manual boost controller. /thread.

It spiked worst with MBC and a horrible boost fade follows it. I'm still having spike, but no fade issue with the LM control.

Beside, I really wanted to take advantage of the feature of the BOOST VS. SPEED table to limited amount of boost at 1st and 2nd gear but allow HIGHER boost on 3, 4, and 5th. Manual controller can't do that.

My punk hole is huge, compare to stock, and I have my wastegate actuator rod tighten down pretty tight to try to resolve the fade issue while using a manual boost controller. I was going to lossen the rod, but never got a chance to do it. And today I have a transmission swap for another car.
http://www.thelostartof.net/tryingbe/forsale/cosworth6.jpg
http://www.thelostartof.net/tryingbe/forsale/cosworth7.jpg

ShelGame
12-03-2011, 02:10 PM
I know it's still consider "spike", but at least it's on a manageable level instead of spiking to 20psi. NO issue with part throttle boost, it goes to where I set it and stays there!

Left it at stock. Since I really have no idea what I was doing. I tried to just change 1 table instead of 2.

http://www.thelostartof.net/tryingbe/dodge/omniproject/tune/boostdc.JPG


This is the table you really wanted to tune. Since you're getting spiking, I would move the last (bottom) point out to your boost target. I think stock it's at like 11psi. So, move that point to the right a bit to match your highest boost target. Then, I would raise the DC a little at that point, and probably the others as well; except the for the 'top' point which is already at 100% DC. More DC = less boost in the LM system...

tryingbe
12-03-2011, 07:51 PM
This is the table you really wanted to tune. Since you're getting spiking, I would move the last (bottom) point out to your boost target. I think stock it's at like 11psi. So, move that point to the right a bit to match your highest boost target. Then, I would raise the DC a little at that point, and probably the others as well; except the for the 'top' point which is already at 100% DC. More DC = less boost in the LM system...

But I tried this and it didn't help.

http://www.thelostartof.net/tryingbe/dodge/omniproject/duty.JPG

Aries_Turbo
12-04-2011, 01:38 AM
sounds like there is something wrong mechanically if its spiking with both the LM control and the MBC.

Brian

Force Fed Mopar
12-04-2011, 11:55 AM
But I tried this and it didn't help.

http://www.thelostartof.net/tryingbe/dodge/omniproject/duty.JPG

I think you need to stretch it down like mine, not sideways like that.

ShelGame
02-01-2012, 10:37 AM
Actually, if setting the boost to 8psi actually keeps it to 12 at part throttle, then you just need to reset the WGDC to reflect that. The WGDC is what ultimately controls boost. Your target doesn't mean squat if you set the DC to 100% you will only get boot up to the can's opening point, for example.

What you need to do is take the duty cycle for 8psi (looks like about 36%DC) and move that value out to 12psi. And move all the other points accordingly. If you want to do it quick and dirty, you can scale the whole x-axis by 12/8 = 1.5. But, I'd also then move the bottom point to 0% DC keeping the same slope. And, move the leftmost point back to ~7psi, 100%DC --> the base point should always be the WG can opening pressure. The DC is meaningless below that pressure as the computer will not be able to control the boost below this value. I photochopped your DC table to show you what I mean.

After adjusting the WGDC table, go back and make your part throttle table 12psi at half throttle and lower. You should end up with the same result.

37175