I have a '98 Z28, with a G5X3 cam, long tubes, open exhaust, 3600 stall, and ported STOCK throtle body. The car idles great, but when I put the car in "P" or put the car in "N" it revs up to about 2,000 RPM and then quickly drops back down to target idle RPM. Then this mourning I drove to work and when I put the car in park, I was setting there for about 15 to 20 sec. and the car started hunting idle real bad, like jumping to 1600 and back down. I have HP Tuners and I've done all of the tuning to the car. Just wondering if anyone has come across this problem before?

Thanks for Any Help!!

 

theres a seperate set of tables for idle in park and idle in gear. im guessing your in gear ones are borked somehow. compare both tables, see if theres any glaring inconsistencies.

 

what "things" have you touched in the tune
did this just start recently after having no problemns for a while..or has this ben something that has always been there..or did it develop as you were tuning

have you done an IDLE RAF for gear and P/N
(this woudl be my guess as to what needs fixing)

you can also send me your tune and I'll take a look for anything obvious..or not so obvious


have you looked at your springs lately??
sometiems a broken or cracked spring will make teh car start hunting for idle as well....my old camaro had that hapen...all of teh sudden just started hunting for ilde(it was cause a spring failed and was not opening properly...choking the engine)

 

I've heard alot of people talk about idle RAF. What is it? Is it a talble or some kind of formula? I've changed: Target Idle Speed vs. ECT, Idle Air Flow vs. ECT P/N and Gear, Throttle follower decay P/N and Gear, IAC Park position vs. IAT, IAC vs. Effective area, Primary VE, Spark advance, Throttle Cracker, and Adjusted Throttle blade set screw. The problem with the RPMs jumping to 2000 when I put it in Park or Neutral, has been a problem sense the cam swap. The problem with hunting Idle just started today. This mourning it was like in the mid 40s as far as temp. goes, if that would have anything to do with my issues.

Thanks again!