1994 Chevy Silverado Engine stalls at cold idle and during

  • V8
  • 2WD
  • 254,000 MILES
Hi, my 1994 chevy 2500 v8 K vin 5.7 liter stalls at cold idle and while driving, but esp when I first crank it up cold. I had this prob a couple wks back and it sent code 35 IAC valve. With throttle body exposed the TB makes loud hissing sound, as if vacuum leak or starved of fuel. Then when this sound goes away, the vehicle runs. I can run up to whatever speed, say 60 mph last night down highway and boom, vehicle dies. Started back up and got it home. This morning, same hissing and stall over and over, then ran fine, then stalled. Not sure IAC valve could cause this vehicle to stall like this at idle or driving at higher rpm. Hope that is what it is though. I disconnected fuel line and tested fuel flow and filter, and it seems that fuel flow is vast. Could it be a fuel pressure regulator, or intermittent fuel pump issue? I tested map sensor, and ignit module and they test fine. Spark or fuel, I don't know, or even a sensor? The hissing at TB is what puzzles me though. When it runs fine, hissing gone, then comes back and boom, vehicle stalls out. Could it be relay? I cannot find a fuel pump relay on this at all. I am just wondering why it sent code 35 IAC valve though. Could that cause vehicle to die at all speeds and idle? Maybe it is a weeks fuel pump. Prior to this problem, a day or two before, I ran out of fuel due to fuel gauge being inoperative. Please help as I would like to be able to see my little boy and girl. Thanks.
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Sunday, September 14th, 2008 AT 2:31 PM

1 Reply

Open up the IACV and clean it out

Here's how to clean the IAC valve:

Disconnect the air intake ductwork from the throttle body.

Start the engine, then increase and hold the idle speed to 1,000 to 1,500 rpm.

Spray the throttle cleaner or engine cleaner into the throat of the throttle body, aiming for the idle air bypass port (usually located on the side or top of the throttle body opening). Give this area a good dose of cleaner (about 10 second's worth).

Turn the engine off to allow the cleaner to soak into the IAC passageway.

Wait about three minutes.

Restart the engine, rev and hold at 1,000 to 1,500 rpm, and repeat the cleaning process again.

Turn the engine off again, and reattach the air intake ductwork to the throttle body.

Start the engine and rev and hold to 1,500 to 2,000 rpm until no white smoke is coming out of the exhaust pipe.

If this fails to make any difference, you can remove the IAC valve from the throttle body and spray cleaner directly on the tip of the valve and/or into the ports in the throttle body. Let the cleaner soak awhile, repeat as needed, then reinstall the IAC valve, start the engine and run it at 1,500 to 2,000 rpm as before until no white smoke is seen in the exahust.

If the idle speed still surges after this, the IAC valve is defective and needs to be replaced.
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Sunday, September 14th, 2008 AT 3:31 PM

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