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'Code 45' Update

I'm Stumped!

'87 Chevy G20 van 350/TH700

I have NO codes and it STILL idles 1200,1400, or higher. No vacuum leaks, Temp switch(for computer) is new, no help at all! I took a look while running and noticed that the nearly new IAC solenoid is wide open, so I swapped it out for one from another TB unit that I know was good...Bout 900 at start, held for a few seconds, and slowly pulled beck and the RPM's started to climb...same problem...

What is causing my IAC to go full open and NOT give any codes?

I am gonna go get an O2 sensor and install it in the parking lot...its about the only thing that I don't have a spare of!

Reply to
Shades
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...1400rpm fully warmed up...

Reply to
Shades

Shades, Had the same thing happen to my 87 K5 blazer. Turned out it was the TB to Manifold gasket had a 1/4 inch piece just missing. Replaced gasket and no problem. Regards, JR

Reply to
JR

I was thinking about that too. Their cheap so I will.

The hardest to fit piece of the puzzle is that when driving in town the other day, it straightened out and didn't idle high...600RPM in gear and smooth. UNTIL, I shut it off and went in the store for maybe 5min, then it was high idle time again!

WTF...

Reply to
Shades

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