98 LS1 dies at idle

[sdhager]

I have my first tune in the shop for a buddy of mine. He has built it a little bit, and the cam lopes at idle. I have not tried to perform a tune yet, but his already has a custom tune that was done mail order. His only concern is the dying at idle sometimes. When this thing is half warm, it dies a lot. One question that I have revolves around resetting the minimum air rate. This thing has about 120-140 IAC counts at idle when warm. What is the concensus about turning the idle stop screw in to raise minimum air rate, thus lowering my IAC counts, and maybe fixing his dying at idle problem? What about TPS?

Would it be better to drill a calibrated hole in the throttle plate so I can raise the min air without affecting TPS?

What are you guys doing on these?

Remember, I have zero experience with custom tunes, but I've been fixing them "factory" for years, so I understand the basic theory.

[Goldfinger911]

My humble opinion:

Do not drill the TB plate!
1. Screw in the stop screw a 1/16 of a turn or slightly less. (it is real touchy)
2. Reset the TPS sensor.
3. Warm up car fully
4. Check IAC counts.
5. If counts are above 60, repeat step 1, 2 and 4.

Once IAC counts are between 40 and 60 then let the car totally cool. Then do the RAFIG process to properly tune Desired Airflow at Idle. Then, if youre picky like me, recheck IAC counts when warm. Then the next day when the car is really cold, repeat the RAFIG proess again.

[sdhager]

Is there a place that has a step-by-step instructions on proper tuning for gas and diesel engines? I would really like to have some more theory before getting too deep.

Thanks.

[joecar]

sdhager, welcome... :cheers:

This may help: showthread.php?t=7866 (http://forum.efilive.com/showthread.php?t=7866) (post #1 contains links to tutorial material).