Help my car pick an idle speed please
Thread Starter
Pro
Joined: Dec 2005
Posts: 709
Likes: 1
From: Lakewood Colorado
Help my car pick an idle speed please
For 88 with stock 350, I mean 5.7L and 4+3 manual
Car runs great otherswise, but when idling it seems to be seeking an idle speed between 600 and 900RPM cycles every 2-4 sec between the extremes.
If you have suggestions on where or what to start looking at I'd appeciate it.
Car runs great otherswise, but when idling it seems to be seeking an idle speed between 600 and 900RPM cycles every 2-4 sec between the extremes.
If you have suggestions on where or what to start looking at I'd appeciate it.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Start checking for vac leaks. You can sometimes hear them as the idle drops. It makes a hissing sound. You can use propane or starting fluid to locate these leaks. Wave the propane around the vac lines or spray the starting fluid on them. When either enter the vac lines the idle will suddenly but slightly increase. I have also hear you can blow smoke into the throttle body and can see the leaks. Never tried it that way though.
I would also remove the throttle body and take the IAC out. Clean both good with throttle body cleaner and a old toothbrush or small nylon brush. You may want to pickup new gaskets for these before hand. When reinstalling the IAC make sure the tip of the pintle is no further than 1 1/8" from the tip of the flange or damage to the motor windings may occur.
Doing both of these is where I would start.
I would also remove the throttle body and take the IAC out. Clean both good with throttle body cleaner and a old toothbrush or small nylon brush. You may want to pickup new gaskets for these before hand. When reinstalling the IAC make sure the tip of the pintle is no further than 1 1/8" from the tip of the flange or damage to the motor windings may occur.
Doing both of these is where I would start.
Le Mans Master
Joined: Aug 2003
Posts: 9,884
Likes: 3
From: Magnolia Mississippi
St. Jude '03-'04-'05-'06-'07
I'd also include resetting the TPS along with the IAC cleaning and setting, procedure under Tech Tips/C4 or search, the procedure is here with additional information...
good luck
good luck
Drifting
Joined: May 2003
Posts: 1,979
Likes: 48
From: Lakeport CA
I'd vote on TPS not giving a low enough output voltage at idle. My non-adjustable on my '90 does all the time. It also factors in speed input. A quick but firm throttle blip AFTER you hit 0 mph (full stop) causes mine to settle right down. But then I have a spare TPS that I'm going to play with next month as well.
Good luck.
Good luck.
