Egr Noise And Fast Idling

[studibel]

1993 'burb 2wd with around 212,000 miles.

 

Idling around 1400 when cold. Have recently replaced distributor with rebuilt to solve a non-run issue. It runs great now, but...

 

Trying to solve codes 32 and 35 (EGR and IAC). CEL light will come on after 10 or so miles of driving. If you accelerate, most times the light will go off. Have replaced IAC motor which didn't affect codes or fast idle. Replaced the EGR because i was sure it was leaking vacuum...chirps/whistles after engine warms thoroughly. Replaced EGR only to have exact same issue with noise...although not quite as bad. I am not clear why the EGR valve would chirp/whistle like that. Could the throttle position sensor or EGR solenoid be the cause of the fast idle and EGR noise? Accelerating will stop the EGR noise...slow down and it returns. So, what's causing the fast idle and EGR noise and codes?

[studibel]

I never received any other input on this topic but I did have some repairs done so I thought I would update this posting for anyone in the future who might have the same issues as mine. After replacing the EGR valve, the EGR solenoid and the IAC motor, nothing ever helped the fast idle nor the EGR chirping/whistling. When I had the truck in the shop for another issue, I asked them to diagnose this chirping for me. They said the throttle body gasket was broken and causing a vacuum leak...which is what I suspected. After changing the gasket, all is fine. No more noises...no more CEL codes! This was a good learning experience for me so hopefully, it will help others. Stu