1995 Yukon High Idle

[Steven94]

My 1995 Yukon is having a high idle issue and I've already replaced the EGR valve, EGR Solenoid, TPS and its still having issues any help is appreciated.

 

[B-train]

Check the gasket under the TBI unit. They are known to crack and disintegrate with age. This will cause a huge air leak and allow it to run faster. Thise didn't use MAF sensors, so the engine doesn't know it's getting more air than it realizes.

 

[Eman85]

95, is it a Vortec engine? If TBI then it's most likely the throttle body gasket. If you have a scan tool check IAC and see if it's being commanded closed, if so it's a vacum leak. A smoke generator is a good way to test for a vacum leak, easy to make one from PVC pipe and Youtube videos.

 

[exp500]

Read the manual section for resetting Idle Air Control. Thats 1st step.

 

[Steven94]

Would a vacuum leak also cause it to have a low idle? Like low to were it sounds like it’s about to die?

 

[exp500]

Your computer also shows codes - OBD1 flashing light on dash then count flashes with proper pins jumpered.
Even disconnecting the battery or dead battery could cause IAC calibration issues.
Download here and search for IAC and OBD to start your servicing education.
- https://www.gmt400.com/threads/88-95-service-manuals.43575/

 

[Eman85]

Let's all get on the same page here.
Is this a 95 with a Vortec 350??
You said you had a high idle now you're talking about low idle.

 

[Fless]

Let's all get on the same page here.
Is this a 95 with a Vortec 350??
You said you had a high idle now you're talking about low idle.

Details, details, details.