JimMueller

iTrader: (9)

My idle had been acting just fine for almost a year, then I decided it had been over 4 years since the motor was built, so it's a good time to use some GM top end cleaner. Hmm, while I'm at it, I'll use MAF Parts cleaner on the Gen4 slot card also.

After killing all the mosquitoes in a 2 square mile area as a result of the top end cleaner, I noticed that the idle RPM has started to hang high randomly in the couple weeks since I cleaned it. How do I isolate whether it's the tune or the sensors which are whacked?

VandykeT/A

I would check for vacuum leaks. Get a scan tool and some starting fluid and have somebody watch the stft's while you spray the starting fluid. If you have a leak they'll climb further into the negative once it picks up the fluid. My car had two major vacuum leaks and just spraying changed my idle none but fuel trims would sky rocket as long as I was spraying. If the car ran good before you cleaned it I don't think it could be the tune. Might try giving the maf another hit of some maf sensor cleaner.

MontecarloDrag

iTrader: (3)

If you cleaned the Throttle body and the IAC passages, it may take a few days to learn the new idle values. It can be done faster with a scan tool but it will learn itself

LilJayV10

iTrader: (39)

First off, don't use starting fluid to check for a vacuum leak. That's just stupid.

You didn't run the top end cleaner in front of the MAF did you?

I'd try the base idle relearn procedure first.

JimMueller

iTrader: (9)

I removed the lid, MAF & tubing and sprayed the top end cleaner directly at the throttle blade. I cleaned the MAF separately while it was uninstalled from the car. I did an idle scan on it last weekend and the IAC numbers were fine warmed up (upper 50's), the TPS % & voltage values were fine. The RAF numbers on a cold start were -2 around 176*, and around -4 to -5 at lower cells, but this has been what's working since last spring no problem.

It seems to have begun behaving correctly again. I'll have to lookup that procedure to refresh my memory as it's been too long.

JimMueller

iTrader: (9)

The vent tube between my TB and the passenger side valve cover wasn't sealing well and was showing signs of cracking. Much better after replacing that hose.