Hello all, new to the forums. I have a 1998 formula with an idling problem. The guy I bought it from said it ran fine. He got it tuned after alot of engine and tranny work. Ran fine. Fixed a vacuum line leak. And now wont idle to save it's life. It gets better once the car is warm and then will idle in park and in neutral, but then as soon as you put it in gear the rpm drop and it dies unless you feather the throttle. Even when it's cold and you take off then let your foot off the gas to coast it will die eventually. I've replace the aic sensor and it didn't change anything. Cleaned the map sensor. Nothing has helped. The guy I bought it from said it just needed retuned. Help!

 

So it was previously tuned for major engine work (assuming cam or heads/cam?), then you found a vacuum leak and fixed it, and now it won't idle as well as before? If I understand that correctly, it sounds like the setup was previously tuned with the vacuum leak in place. Fixing the leak has changed things and the old tune may have been compensating for said leak; if so, it would in fact need to be retuned now for best idle. I encountered this once on another LS1 car, it was a heads/cam car that had been tuned with a leak in the PCV system, but it idled pretty well. Once that leak was fixed, the idle was horrible and it needed a retune.

 

You are correct. The work and tune was all done by the previous owner. He fixed the leak and it started to do it. Then I bought it from him a week or two later and now it's my problem, but thank you for the information. Makes me feel better that it's something fairly simple, although expensive, but at least I can quit wasting time and money trying to change other things. Any other input is appreciated