Picco02

iTrader: (1)

I need some advice on the problem I am having, basically to make a long story short I have a 02 Z28, It has basic bolt-ons, (LT headers, slp air lid, ect.) and last Jan I installed a Texas Speed 228r cam ,228/228 .588/.588 and 114 LSA. and beefed up the valve train. It runs great, i sent the PCM to www.madtuner.com for a mail order tune. Now everything seems okay except when I rev up the motor from a idle (warm or cold) the idle hangs, just coming down from 2,500 can take 10 or 12 seconds. It'll drop very slow, from a quick rev up. It should be really snappy after a rev. I have a buddy with HP tuners that is going to help me mess with it this weekend, I am just looking for some insight if anyone knows where we should look first or what we should adjust first. My idle is set around 700 i believe. We have had the idle higher before and it didnt make a difference. Also when I am at a roll with the clutch in coming up to a stop light the idle sometimes drops way low, like below 500, sounds like it will die but immedietly comes back to a idle.

thanks

Picco02

iTrader: (1)

should I adjust the throttle follower decay rate? increase the rate and idle will drop quicker?
or does the throttle follower not have anything to do with idle at 0 mph in neutral?

MMWS6

First make sure your IAC Park position table is stock. If it has been raised, that is wrong and needs to go to its stock settings. If they are stock then it sounds like your Park/Neutral Decay table is set too high. Take out a couple of % at a time until you get a nice controlled return to idle. Make sure that there was only 2g/sec added to your idle air table over stock and only 4* of idle timing added under 1200rpm, including 1200rpm actually. Check your tune for those first and see what you find...

MMWS6

Bump the idle 100-150 RPM for now as well while cleaning it up. Once you have things nice you can lower it again... but you really don't want that shake man, that's old world thinking right there. Put that idle RPM in a range that will keep things fairly smooth. I like to enable live controls, watch oil pressure and when it comes steady without needle jumping around on the dash, use that as your set idle rpm. Your call though, everybody has their preferences with idle rpm