Idle impossible to dial in

[97rs4life]

Well I am having a heck of a time dialing in my idle from a cold start. It searches up and down until the engine gets up to 180* then it settles in. This is in park

A/F ratio is a bit rich during this, it bounces around in the 13.xx range and sometimes touches 12s.

I have added timing to the idle area and it seemed to not really do anything.

My battery is getting weak, but still starts the car so I doubt that has any affect.

Car is a 97 camaro 3.8l v6. Engine is fully built and cammed with the abbott NA cam, 42.5# injectors, 42psi fuel at idle, 85mm vette maf, and if you need more info let me know.

I attached my current tune and the cold start log that I took to show how it varies up and down.


PLEASE HELP!!! I am ready to drive this car off a cliff!

[super6ute]

According to your scan you are running negative timing.

I would load the stock tune in with the modified inj flow rate for your 42# injectors.
If that fixes it, 1 change at a time, work your way back to what you have until a problem shows.

I am not familar with tuning V6's but should the 2nd bank of injectors be operating in the scanner?

[97rs4life]

According to your scan you are running negative timing.

I would load the stock tune in with the modified inj flow rate for your 42# injectors.
If that fixes it, 1 change at a time, work your way back to what you have until a problem shows.

I am not familar with tuning V6's but should the 2nd bank of injectors be operating in the scanner?

v6's are like that for timing in the scanner, it really is positive timing. Kind of confusing I know. lol

[Andy0x1]

For what it's worth: A buddy of mine has an LS1 with the same idle problem. Amazingly replacing the battery fixed it - never would have guessed.

----

I have an L67 with similar idle issues... it surf's up and down in park, if you enable VCM control, and simply choose an IAC step setting, it idles perfect.

I know replacing the IAC motor can sometimes help.

----

I've seen idle problems with a Mini AFC on a 3.8 too... I think the PCM expects a certain MAF Hz range at idle, and if it see's values that are too far from reference, it will consider your MAF to have failed, and will go to a default table.

----

Those are all things I wanted to through out there, however I doubt any of of em are your problem.

I contacted Support to see if they could unlock the ability to further fine-tune the IAC control so it doesn't overshoot back and forth. According to William Henn, it is on their list of things to do for our application.

[IndeedSS]

Because we don't have idle airflow tables, some including myself have drilled holes in the throttle body blade to get the extra air at idle the engine wants. Every setup will be different, but for my current setup, and the one when I had the XP cam, two 1/8" holes made the most improvement without going to far. I tried one hole centered in the lower half of the blade, which helped. Then I drilled another hole centered in the top half of the blade and that worked real well.

Ive heard that some of the big cammed V8 drill throttle body blades as well.

[super6ute]

v6's are like that for timing in the scanner, it really is positive timing. Kind of confusing I know. lol

Cheers, always something new to learn.



If it were a V8 it would be as simple as increasing the idle airflow values, as mentioned above.

Also to ensure a smooth transition to your main spark table, ensure your idle/park and main ignition tables are similar in the idle area.

Once you give it some more air, there is no reason why it shouldn't idle nicely at 10 degrees timing.