my idle is set at 1100 but recently when i pull up to a light/stop sign and put the car in neutral my idle rises to about 13-1400...stays there for a few seconds then dies down. checked my lid/cleaned the maf and tb. still have the issue. any ideas?

 

if you're hard on the brakes, you're lowering the vacuum in the intake, and therefore raising the idle... (going from vacuum to atmospheric pressure)

Odd thing.. I was JUST thinking of this earlier. "I'm surprised I haven't heard this question on the boards yet.. "

 

LS1s act funny like that when you do cam swaps on them if they aren't tuned 100% (and by 100%, I'm talking about being tuned for hours)

It's nothing to worry about. Try swapping with someone's else's MAF if you're honestly concerned.

Mike

 

thanx 4 the replys! just tryin to work out the small things...its easier to diagnose when theres a huge grinding or thumping sound haha

 

Another idea... the throttle position sensor. My TPS recently took a dump. The first sign was that the engine would idle fast after it had warmed up. Long story short the Service Engine Soon light came on a few months after I first noticed the high idle. I pulled the code and it came up as a throttle position sensor error. Anway, I replaced the TPS and all is back to normal. Not sure in you case sense you have quite a few engine mods. Just an idea.

 

no SES light yet but that would make alota sense. wouldnt be the first sensor to have gone out recently...thanx!

 

Not going to be the TPS.

What you're talking about is surging/searching due to a cam swap when coming to a stop. Lots of cam-swapped cars do this without perfect tuning.

 

hmm so get a better tune! gotta get the speedo recallibrated for the 4.11s...might as well drop it off for a couple more hrs to get re tuned

 

Tell them to check the IAC values and if they can't get it right with that, they may have to drill the throttle body.... I can't see them not getting it right with only a LS1 Hot Cam, though..