rough idle speed performance, 92 s-10 4.3L TBI

[R72K5]

i need to know of anything that may or is known to cause erratic and variable idling speeds/bad idle performance on a 92 s-10 4.3L TBI engine, so far we put new fuel pump in and replaced wiriing harness from the distributor to the coil and also the spark plugs and i cleaned off all the carbon that was on the IAC motor and hole for it in the TBI unit

truck otherwise runs great all other RPM's andc on the freeway except now and then it will bog out for a couple seconds when are traveling constant speed ont he freeway, as if its dying shutting off and then it will just out of the blue regain RPM and keep on going like nothing ever happened, when it does this then the check guages and the check engine light both come on, otherwise only the guages light comes on now and then for only a few seconds

thanks for anything

 

[4by4bygod]

You might have a bad EGR valve. That wil cause it to idle very rough, but still run good on the highway.
Tom /forums/images/graemlins/usaflag.gif /forums/images/graemlins/k5.gif

 

[4xcrazy]

How old are the spark plug wires, i had a similar problem with our 1/2 ton truck with the 4.3, replaced the cap,rotor,plugs,filters,coil, and still had the problem, finally, i changed out the "factory original" plug wires and it was cured, seems we had one grounding out behind the motor somewhere.

Being that the 4.3 is only a 6 cylinder, if you drop even one, it will dog out on ya big time.

 

[R72K5]

[ QUOTE ]
You might have a bad EGR valve. That wil cause it to idle very rough, but still run good on the highway.
Tom /forums/images/graemlins/usaflag.gif /forums/images/graemlins/k5.gif

[/ QUOTE ]

thought about that so i went ahead and plugged the vacuum source to it, diidnt change anything so far.

thanks /forums/images/graemlins/laugh.gif

 

[R72K5]

[ QUOTE ]
How old are the spark plug wires, i had a similar problem with our 1/2 ton truck with the 4.3, replaced the cap,rotor,plugs,filters,coil, and still had the problem, finally, i changed out the "factory original" plug wires and it was cured, seems we had one grounding out behind the motor somewhere.

Being that the 4.3 is only a 6 cylinder, if you drop even one, it will dog out on ya big time.

[/ QUOTE ]

wires and plugs are replacement i know, weve prety much been all over the entire engine, even have dropped the fuel tank a few times but gota do it once again to replce the fuel sender unit and the pump with nw parts

thanks /forums/images/graemlins/laugh.gif