1992 GMT400

[edwadway]

Hello I’m from the South , I have an 1992 GMT400 / C1500 4.3 Liter V6
Automatic, I am having rough idle, I have changed the MAP , Throttle PS, EGR valve and Solenoid, ETC sensor on intake manifold, IAC on Throttle body, still having mirrors shake at stop sign, run smooth when accelerating, but sitting at a light idling, runs bad, , please help? Also changed the O2 Sensor, also replace Fuel pressure regulator, bought 2 Fuel injectors, but had one installed backwards, and need to correct it, not sure what else to do. Bought a Vapor vent valve, but don’t know where it goes.

 

[Blue85]

Behold the power of the parts cannon! Have you checked around the intake and the vacuum lines for a vacuum leak? Is the engine affected at all from pushing the brake pedal? How do the plugs look? If no other leaks are found, it's always possible for new parts to be bad, so you could try disabling/plugging the EGR to see if it's staying open when it shouldn't. Do you have a scan tool?

Welcome to CK5!

 

[edwadway]

the plugs , wires, rotar, distributor cap, and coil was replaced with AC Delco wires and plugs, no vacuum leaks, I think it 4 vacuum lines on the throttle body, and they all good, I did have a collapsed line on PVC and I just knew that was the issue but it was not, but yes, if I am at a stop sign with car in drive holding brake it rough idling, , but as long as you giving it acceleration, runs perfectly

 

[edwadway]

Behold the power of the parts cannon! Have you checked around the intake and the vacuum lines for a vacuum leak? Is the engine affected at all from pushing the brake pedal? How do the plugs look? If no other leaks are found, it's always possible for new parts to be bad, so you could try disabling/plugging the EGR to see if it's staying open when it shouldn't. Do you have a scan tool?

Welcome to CK5!

O no I don’t have a scan tool, for OBD 1, I can get one if it a certain one that recommended

 

[Wes Harden]

Tbi base gasket is notorious for spliting between the 2 venturi, and causing a vacuum leak.
The throttle shaft bushings wear and leak vacuum.

A vacuum guage reading at idle could point us toward a solution.

 

[imiceman44]

the plugs , wires, rotar, distributor cap, and coil was replaced with AC Delco wires and plugs, no vacuum leaks, I think it 4 vacuum lines on the throttle body, and they all good, I did have a collapsed line on PVC and I just knew that was the issue but it was not, but yes, if I am at a stop sign with car in drive holding brake it rough idling, , but as long as you giving it acceleration, runs perfectly

When you press the brakes do you hear any hissing noise?
It helps if you have someone pressing the brakes and you listen at the brake booster for air leaking internally

 

[USSkoval]

Is it just simply idling too low? I've run into that many times on TBI 4.3's and V8's.

 

[edwadway]

When you press the brakes do you hear any hissing noise?
It helps if you have someone pressing the brakes and you listen at the brake booster for air leaking internally

No

 

[edwadway]

Tbi base gasket is notorious for spliting between the 2 venturi, and causing a vacuum leak.
The throttle shaft bushings wear and leak vacuum.

A vacuum guage reading at idle could point us toward a solution.

Okay

 

[edwadway]

Behold the power of the parts cannon! Have you checked around the intake and the vacuum lines for a vacuum leak? Is the engine affected at all from pushing the brake pedal? How do the plugs look? If no other leaks are found, it's always possible for new parts to be bad, so you could try disabling/plugging the EGR to see if it's staying open when it shouldn't. Do you have a scan tool?

Welcome to CK5!

Thanks