So what are you guys doing about 4th/5th gear knock?

[Force Fed Mopar]

No, the 1* is the total advance. When you set the timing with a timing light you aren't actually setting the timing, you are just syncing the crankshaft with the distributor/computer.

[wallace]

ok I see thanks for the info.

[wallace]

No, the 1* is the total advance. When you set the timing with a timing light you aren't actually setting the timing, you are just syncing the crankshaft with the distributor/computer.

So if the base timing is 10* and the computer adds 1* as in the chart you posted the actual advance is 11*?

[Force Fed Mopar]

So if the base timing is 10* and the computer adds 1* as in the chart you posted the actual advance is 11*?

The total timing is the RPM timing table + whichever Map timing table is being used (WOT or Part Throttle). The Calculated Timing chart I posted shows the total timing. This can be modified by either Knock Retard or the Spark Scatter (at idle).

Initial timing is whatever the RPM Timing table shows at 1k. Think of the RPM Timing table as the mechanical curve of an old style distributor, and the Map Timing tables as the vacuum advance.

At least, this is my understanding of it. If I am wrong I am sure Rob L. will correct me

[Force Fed Mopar]

So I set the Knock Threshold back to stock MP specs, didn't see any knock on a 3rd gear pull at 22+ psi. Didn't hear any either, but I still need to double check the wiring connection at the SMEC (have had issues with it before).

[eski]

Nice finding. Keep us posted.

[Force Fed Mopar]

Lol, just found this on allpar, quoted from one of the 2.2/2.5 turbo development engineers:

Our biggest difficulties lay with detonation, or the detonation sensor which was, I think, unreliable. Given this, the specified fuel could not be regular octane. I fought this battle and eventually won something in the owners' manual saying better performance and longer life could result from the use of high octane fuels. This was a big breakthrough. I had several different turbo lease cars and they were fine; they never tasted low octane fuel.

http://www.allpar.com/mopar/22t.html

[cordes]

Lol, just found this on allpar, quoted from one of the 2.2/2.5 turbo development engineers:



http://www.allpar.com/mopar/22t.html

I've read that before. He also gives us these gems.

[Of the production engines], the 1988 version with the longer branch tuned intake manifold was the best.

Turbos are for racing. Too much heat for normal driving. We should have gone with that Eaton Rootes-type supercharger.

ETA: There are so many factual errors on that page it's not funny.

[ShelGame]

So if the base timing is 10* and the computer adds 1* as in the chart you posted the actual advance is 11*?

I just saw this...

Actually, if you're 'base' timing is set to 10*, and the tables give you 1*; then your actual advance is -1*. Becuase the computer thinks the 'base' timing should be 12*. So, you start out 2* retarded.

As already mentioned - the 'base' timing is not actually added to anything. It's just the advance used when syncing the distributor to the crank. So, it only comes into play if it's different from what the computer thinks it should be (in almost every cae, that's 12*).

[wallace]

I just saw this...

Actually, if you're 'base' timing is set to 10*, and the tables give you 1*; then your actual advance is -1*. Becuase the computer thinks the 'base' timing should be 12*. So, you start out 2* retarded.

As already mentioned - the 'base' timing is not actually added to anything. It's just the advance used when syncing the distributor to the crank. So, it only comes into play if it's different from what the computer thinks it should be (in almost every cae, that's 12*).

Hey I mean to put 12 instead of 10 for factory base timing setting. So if the table showed 1* the total advance would be 13 correct? Thanks for the clarification.

[shackwrrr]

Hey I mean to put 12 instead of 10 for factory base timing setting. So if the table showed 1* the total advance would be 13 correct? Thanks for the clarification.

If the table shows 1 then the timing is 1.

[shackwrrr]

Rob do you have your cal posted anywhere? Id like to compare it to mine. On your calculated table, timing in the higher RPM's in high boost is much higher than mine. The only place yours is lower than mine is the midrange. My minimum timing is 10.5* and I have no mid range knock, Only a small click every once and a while when the auto downshifts from 3rd to second. I do however see a lot of knock above 20 psi right now.

Mine is in a van so the load in 3rd is pretty high. I only see that little blip on downshifts going up hills

[wallace]

If the table shows 1 then the timing is 1.

Are you saying that the ECU can retard the timing further than the base setting of 12*?

[Force Fed Mopar]

Rob do you have your cal posted anywhere? Id like to compare it to mine. On your calculated table, timing in the higher RPM's in high boost is much higher than mine. The only place yours is lower than mine is the midrange. My minimum timing is 10.5* and I have no mid range knock, Only a small click every once and a while when the auto downshifts from 3rd to second. I do however see a lot of knock above 20 psi right now.

Mine is in a van so the load in 3rd is pretty high. I only see that little blip on downshifts going up hills

Rob L runs race gas If you are running a 2.5 swirl, you need to retard the timing heavily above 15 psi for pump gas 93 oct.

Are you saying that the ECU can retard the timing further than the base setting of 12*?

What he is saying is that the "base" setting does not come into play at all in timing calculation. It merely makes sure that the distributor is sync'd to the crank and cam. Once you do that, the timing will be whatever you see in the calculated tables. And yes, it can retard or advance it as much as you want, it is only limited by the LimitForHotMapAdvance and AdvanceFromRpmMax tables. I have mine set to pull it all the way down to 1* total in low rpm/high boost situations. Stock 2.5 has a minimum limit of 10*, stock 2.2 SMEC has a minimum limit of 16* after 2400rpm.

---------- Post added at 08:42 AM ---------- Previous post was at 08:37 AM ----------

I've read that before. He also gives us these gems.






ETA: There are so many factual errors on that page it's not funny.

I wouldn't say that, I would say he's pretty close to spot-on. Except the part about turbos lol.

[wallace]

[QUOTEWhat he is saying is that the "base" setting does not come into play at all in timing calculation. It merely makes sure that the distributor is sync'd to the crank and cam. Once you do that, the timing will be whatever you see in the calculated tables. And yes, it can retard or advance it as much as you want, it is only limited by the LimitForHotMapAdvance and AdvanceFromRpmMax tables. I have mine set to pull it all the way down to 1* total in low rpm/high boost situations. Stock 2.5 has a minimum limit of 10*, stock 2.2 SMEC has a minimum limit of 16* after 2400rpm. [/QUOTE]

1 degree of total advance? Wow.

[ShelGame]

Are you saying that the ECU can retard the timing further than the base setting of 12*?

Yes, actually it can. It can even go negative (IE, After TDC)

But, that's not the point. The point is 12* is not really 'base timing'. It's just a reference point. When you unplug the coolant temp sensor, the ECU fixes the advance at 12* (none of the tables come into play, spark scatter idle control is turned off) simply for the purpose of synchronizing the HEP with the crank position. So, when you use a timing light and set the timing to 12* on the flywheel, the HEP is now perfectly sync'd with the crank. When you plug the CTS back in, the engine controls timing again normally.

The 12* does not get added to anything and actually never comes into play outside of the sync process. So, it's not actually 'base' timing at all. It's just a reference point, nothing more.

Now, here's where it gets tricky - if you sync the HEP at 10* instead of 12*, the ECU has no way of knowing that. So, the result is that ALL of the timing calculated will then be 2* retarded from the actual position. But, this is only due to the fact that the sync is off by -2*.

I hope that all makes sense.

[wallace]

Yes, actually it can. It can even go negative (IE, After TDC)

But, that's not the point. The point is 12* is not really 'base timing'. It's just a reference point. When you unplug the coolant temp sensor, the ECU fixes the advance at 12* (none of the tables come into play, spark scatter idle control is turned off) simply for the purpose of synchronizing the HEP with the crank position. So, when you use a timing light and set the timing to 12* on the flywheel, the HEP is now perfectly sync'd with the crank. When you plug the CTS back in, the engine controls timing again normally.

The 12* does not get added to anything and actually never comes into play outside of the sync process. So, it's not actually 'base' timing at all. It's just a reference point, nothing more.

Now, here's where it gets tricky - if you sync the HEP at 10* instead of 12*, the ECU has no way of knowing that. So, the result is that ALL of the timing calculated will then be 2* retarded from the actual position. But, this is only due to the fact that the sync is off by -2*.

I hope that all makes sense.

It does and I believe I've got it now. Thanks for the explanation, I'm a little slow on the uptake.

[ShelGame]

It does and I believe I've got it now. Thanks for the explanation, I'm a little slow on the uptake.

Nah, I think the 12* was misunderstood for so long that it's hard to wrap your head around what it's really for...

[zin]

Didn't I read somewhere that the factory choose 12* simply because an engine won't idle very well with 0*? That the 12* was a number that would be easier to deal with for technicians...

Mike

[ShelGame]

Didn't I read somewhere that the factory choose 12* simply because an engine won't idle very well with 0*? That the 12* was a number that would be easier to deal with for technicians...

Mike

That was my theory, I don't know for sure why they chose 12*...