91 350 TBI High idle

[dhumboldt12]

So i've got a 91 K1500 with th 350 TBI, when I start it up, it idles around 1500-1700 in park, and when I put it in gear (D) it drops down to about 1000. When it gets all warmed up, it idles about the same, but when I put it in park after warmed up, the idle jumps to almost 2000 before falling down to 1500.

 

[sweetk30]

more than likely sucked in tbi unit to intake base gasket .

when they suck in over time they create huge vac leak and makes them do high idle .

spray a little brake cleaner around the base were the tbi bolts to the intake with it running . . . see if rpm jumps . if so there ya go .

napa part # FPG 60903 under 10 bucks . easy to change.

 

[paratrooper307]

^That's probably your culprit, particularly if you haven't been messing with anything else.

 

[dhumboldt12]

Here's what Im working on figuring out, is that the PO said it was cammed and bored out. So that leads me to believe that they ended up screwing with the idle screw, but who knows. I'll check into the base gasket. Thanks.

 

[rampage]

Way back in my early days I had the same symptoms when I failed a smog test due to high idle. The good people on here gave the same suggestion of spraying around the intake gasket with carb cleaner to see if it raised the rpm. I balked at that - but tried anyways just to prove them wrong. Ended up proving myself wrong. After changing the gasket it passed smog with flying colors ... and the winner of the $50 reward that I had up for grabs refused to claim his prize.

 

[sweetk30]

we tend NOT to give bad info here . and just glad we could help .

now if he did put in a big cam the stock chip for the tbi computer will NOT like that and run crappy . if this is true it will need a custom burnt chip with someone who knows how to do this .

 

[rampage]

Just noticed, you from Humboldt, CA I assume?

 

[rampage]

Any updates?