High idle and a obd1 code 35

[chevyaz]

Hello forum I just had my freeze plugs replaced on my truck and when i got it back from my guy that did the work it was running good. Now i have a high idle. Once its warmed up it runs good but idle is still high in park neutral. And it sets a code 35 iac valve . What the heck is going on here? It ran good before the freeze plugs change. My truck is a 94 gmc silverado truck with a 350 5.7 engine.

Topic

[Andrew Phillips]

Sounds like a vacuum leak or disconnected hose in or around the intake. The IAC is basically a controlled vacuum leak. If there is an additional (uncontrolled) vacuum leak, the computer will not get the results it expects when it moves the pintle on the IAC and throws the code.

[chevyaz]

There is no vacuum leak. And hoses checked out good. Probably should just change the iac. And see whats next.

[Tommy]

Did you find the source of this problem?

[chevyaz]

No sir, I fixed the problem. I changed the IAC and its all good. 323,000 miles strong.

[Tommy]

Oh ok. Mine is having close to the same problem. Cold start has an erratic idle until it starts to warm up. Runs fine once warmed up but if I put it in park with A/C off it pops a code 35. Replaced iac twice and still the same problem.

[Author]

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