Rough Running S-10

[JeffK]

Hi. I have a 1994 S-10 Blazer, 4.3L with about 85k on it. A couple days ago it began to run real rough. While idling, the engine revs up and then drops off... it sounds louder too. When I am driving a highway speeds I do not notice it as much, but when I let of the gas and begin slowing it gets more and more noticeable. Any thoughts....
Thanks
Jeff

ps... I just checked the EGR Valve. I pulled the valve, plugged the hose and it ran the same way... rough!!

[Scorpio7]

Have you replaced your Throttle Position Sensor? It sounds like a problem that this piece causes when the transmission (automatic) and the idle speed control are also not working properly.

Have you any engine light codes flashing on your dashboards??

Later Angelo/Scorpio7

[nevinsb]

I bet you got a chunk of carbon in your EGR valve. The same thing happened to me. The engine surges and just about dies. The new gasket has a screen in it that will prevent foreign objects from entering the EGR valve. This is a very common problem with that motor. Using a top engine cleaner such as seafoam to remove carbon usually can cause large chunks of carbon flyin' round the cylenders to get lodged in the EGR valve, so If you are planing on doing so, do it BEFORE you take the EGR valve out so you don't have to do it twice.

[ddjaa]

Originally Posted by JeffK

Hi. I have a 1994 S-10 Blazer, 4.3L with about 85k on it. A couple days ago it began to run real rough. While idling, the engine revs up and then drops off... it sounds louder too. When I am driving a highway speeds I do not notice it as much, but when I let of the gas and begin slowing it gets more and more noticeable. Any thoughts....
Thanks
Jeff

ps... I just checked the EGR Valve. I pulled the valve, plugged the hose and it ran the same way... rough!!

Hey, got the same problem with 92 blazer, runs ok once you get moving then if you go to stop it surges and stuff. You go to start it after awhile you have to give it gas, whats up????????