454 High Idle
 

Hey guys this is my first post on the forum. I tried searching but couldnt find what I was looking for. I have a 95 K2500 w 454 TBI in it. The truck seems to idle higher than I believe it should. Sometimes when I am on a wet surface or grass just putting it in gear spins the tires slightly. Are there some things I can check before I start throwing parts at it. This is my first TBI owned vehicle. What controlls the idle on this engine? Thanks guys

Does it ever come down once the truck warms up? I noticed my 1995 454 idles high (about 1200 rpm) for the first couple minutes too, but it comes down once it warms.

Yes when I first start it up it goes up to almost 1500 rpms then it will go down to about 1000 but it still seems to high. In gear it is around 800 rpms. I can put the truck in drive and it will accelerate to 40 mph on its own in about 45 secs. I cant drive the truck in the winter without it being in 4wd or the truck will fishtail all over the place just off idle.

I thought back in the day TBI base gaskets were common for a vacuum leak causing a high idle?

Yeah try the starter fluid spray diagnoses. Spray around the intake in short bursts while its idling to see if it comes higher. This will tell you if you have a vacum leak.

Not sure if you have a check engine light on, but it you do it could be an Idle Air Control Sensor. Believe it is code #35 on a scanner, "Cannot regulate idle RPM." This went out on my '94 Chevy, and '94 GMC.

I agree with Acnas. common problem w/TBI. hold your hands over the TBI inlet w/ air cleaner removed. If engine donesn't start to choke out then its drawing ait from the TBI base plate.

I checked for Vacum leaks today and found nothing. TBI gasket actually looks like its been replaced not to long ago. Is there a way to test the Idle Air Control valve? Engine light has not been on at all.

Had the same problem on my 1990 454 Suburban. Fixed with the Idle Air Control Sensor. But check the obvious stuff, vacuum, timing, etc..
Good Luck.

idle
 

i have same problem with my 90 gmc 3500. air control replaced ,gasket replaced. timing set,still idles high,worse in reverse