94 454, GMC Suburban -Idle Air Control, O2, TPS, Fuel Pump relay all replaced-still code 12, 36

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jamesT

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* Sorry, forgot the year, make, model. 1994 GMC Suburban 2500C, 7.4. Thank you.

Like the title says, all new replaced. Last new sensor was the O2.
- Truck stalled, I restarted it. Codes reset, no engine light.
-Idle finally kicked down and it ran great.
-week later, light comes back on, high idle again, light on again.

Went through old threads, can't seem to pinpoint diagnosis.

By the way, I absolutely love this place. You guys are great. These are my first two trucks and you have all been such a help!
 
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1997

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36 - Auxiliary idle air control valve - Wiring, idle air control valve, vacuum pipes, ECM
 

jamesT

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Well, I changed the idle air solenoid. Worked great for about a week. Then, light came back on. Now today, I am going to change the EGR valve. See if that helps the suctioned feeling, sticky gas pedal.

The new solenoid has on open port, the old one had some foam over that said port, not sure...
 

Schurkey

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The foam is a "filter" that the new item should have also.

Maybe there's some internal filter...

If the gas pedal is sticky, it may not close properly, leading to high idle. A worn throttle body can cause this. Repair is to remove the throttle plates, throttle shaft, TPS, etc., and re-bush the throttle body.

Connect a scan tool, look at the IAC movement and TPS.
 

jamesT

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The foam is a "filter" that the new item should have also.

Maybe there's some internal filter...

If the gas pedal is sticky, it may not close properly, leading to high idle. A worn throttle body can cause this. Repair is to remove the throttle plates, throttle shaft, TPS, etc., and re-bush the throttle body.

Connect a scan tool, look at the IAC movement and TPS.
Thanks Schurkey, yes I am looking at at throttle body rebuild here shortly. I bought throttle body cleaner as well as carberator cleaner which says good for tbi? Going to clean it out as well as the sensor port for the EGR valve and see how it runs. Going to order a rebuild kit off Rockauto and see how it goes. Thank you so much.
 
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