Idle SA question

[WillExoIX]

It was recommended to me that my Idle SA cells be 10* more than my base timing to reduce the tendency for idle surging. This from a reputable source.

Aside from the fact of not having a IAC connected till everything is squared away and I pick up an MS2 processor.

Here is my dilemma, You may recall my Spark dropout under load thread, where incorrect rotor phasing and faulty ICM in concert with a leaking EGR were causing the issue.

Here is what was done to correct it. Rotor phasing incorrect at 10* base timing, Pulled dizzy up and retarded it by one tooth, which in turn brought my base timing to 0*. Put the corrected value into the Megasquirt, so the Megasquirt compensated, and essentially made the base timing 10* while the bypass wire is connected. Bypass wire disconnected, base timing steady at 0*. BAM, problem solved.

Onto the question.
Taking into account the previous paragraph, and the tip to set Idle SA cells to 10* more than base timing for a smooth idle on my motor.
The question is, am I setting the Idle SA cells to 10* or 20*? Which value is the "actual" base timing, the 0* base, or the compensated 10* base in the MS?

MS1 V3 running extra code.

I don't see where a log or tune would help, but if you need them just let me know and I'll post them up.
Thanks

[WillExoIX]

Hmm, guess there is a first time for everything.

I'll just assume base timing is 10* as it normally would be on my motor....

[kjones6039]

All I need to know is which one of you actually wrote the post????

Ken

[WillExoIX]

All I need to know is which one of you actually wrote the post????

Ken

The raccoon of course, I'm too busy working on the car lmao!

[WillExoIX]

Would the difference between rising edge and falling edge be 10*? Could that be the reason, perhaps its set wrong?

[WillExoIX]

Would the difference between rising edge and falling edge be 10*? Could that be the reason, perhaps its set wrong?

Nobody has any input?

[Matt Cramer]

The best way to determine the difference between the edges is with a timing light.

[WillExoIX]

The best way to determine the difference between the edges is with a timing light.

So switch it from one to the other and verify timing values with the light?

Could that possibly be the reason it idles so rough? Or is that from adding a restriction to the exhaust (turbo). Idle was smooth as butter before the turbo was added.

[Matt Cramer]

So switch it from one to the other and verify timing values with the light?

Just verify what you've got now.

Could that possibly be the reason it idles so rough? Or is that from adding a restriction to the exhaust (turbo). Idle was smooth as butter before the turbo was added.

Could be this setting or it could be some of the mods when you added a turbo.

[WillExoIX]

So switch it from one to the other and verify timing values with the light?

Just verify what you've got now.

Could that possibly be the reason it idles so rough? Or is that from adding a restriction to the exhaust (turbo). Idle was smooth as butter before the turbo was added.

Could be this setting or it could be some of the mods when you added a turbo.

Well right now with the bypass unplugged its 0* base timing. Standard base timing on this motor is 10*, but there was a rotor phasing issue before the turbo went on that was partially solved by bumping the distributor back one tooth. That caused base timing to go from 10* to 0*, but was compensated by setting the MS to 10* timing for the base value, or setting the MS to 0*, I can't quite remember which. The MS compensates for the changed base timing, and all was back to normal, put it that way.

Tomorrow I will switch the setting and see what happens, Because if possible I would like to be able to put everything back the way it was beforehand, instead of band-aiding what ever the underlying issue was. It was a completely brand new distributor if it matters, and installed properly.

[WillExoIX]

Didn't get a chance to check this as I was getting a log for my other issue. I will check it soon.

[WillExoIX]

So switch it from one to the other and verify timing values with the light?

Just verify what you've got now.

Could that possibly be the reason it idles so rough? Or is that from adding a restriction to the exhaust (turbo). Idle was smooth as butter before the turbo was added.

Could be this setting or it could be some of the mods when you added a turbo.

Quick question. Do you want me to check this with the bypass unplugged? As in base timing?

[Matt Cramer]

Check with the bypass connected.

[WillExoIX]

Check with the bypass connected.

Timing matches what is on screen in tuner studio. It does jump about 1* one way or the other at idle. Rock steady with the bypass unplugged.

Trim angle was at 1*, I set that to 0.

EDIT-I see now that this was before I figured out that I had a dead cylinder from a rocker being to tight. I have since fixed that and it runs smooth again. Though I think I can finally put the distributor back where it was, because I discovered improper dwell settings for GM HEI.