98 Sierra Egr Valve Problem

[dannyboy20]

Ok my truck has been running rough at low speeds. I had the EGR Valve replaced back in July. Had the mechanic run the scanner and everything points to the egr valve. They then cleaned it and got it to pass inspections. Now its doing the same thing. Do I have a falty egr or could it possibly be something else.

[gregrocks89]

does it run like shit? and if you keep it at a certain speed and your light on the throttle does it run like crap?

[dannyboy20]

yes exactly. Pretty much 1/4 throttle it runs really rough. But anyhing over that it runs fine.

[gregrocks89]

hmm yeah one would think the egr would have something to do with that. I had a similar problem that it would run rough when at slow speeds or if im driving around the city and im doing about 70km/h constant for a few minutes it started sputtering. It later turned out to be my plugs on my truck and a few faulty spark plug leads. To check your leads just get a multimeter and see what there is for continuity. Have you checked those? Also maybe your air filter? Another thing to try is when your truck ideling get a wrench and smack your Mass air flow sensor on your intake. Just on the side of it and not hard so that breaks it. What that does is sometimes in the year of our trucks and earlier sometimes they would run like shit for no reason and just smacking that sensor sometimes help with running.

 

This is my 3rd truck in this style and had all similar problems to what you described and thats all i did.

[dannyboy20]

I last replaced the plugs at 90K. Im now at 149500 so that might be something to look at. My mechanic seems to think that there is carbon in the egr. I cleaned it the other day with the same results. He also suggests taking off the intake manifold and cleaning the entire thing.

[gregrocks89]

Yeah ive done that before with the truck i own now. I took the whole air induction off and cleaned every little thing. then moved to the throttle body and took it off the truck and cleaned it up. it had a bunch of gunk and crap in it. It made a difference in my truck.

[dannyboy20]

Did that clear up the problem. Also how labor intensive was the entire job.

[gregrocks89]

Yeah that solved my problem anyways. It wasnt to bad. I did all that in afternoon. But i was really taking my time. Is it stock air induction on there? Mine i got is aftermarket and its really easy to take off. With the stock one i had to fight with it to get it back on but all and all wasnt to bad.

[gregrocks89]

you could almost probably get away without taking the throttle body off and just clean what you can get to

[dannyboy20]

yeah i have a stock induction. Just looking under the hood it looked like it would be a pain. There is alot of things bolted on and around it.

[gregrocks89]

Yeah its not to bad taking it off some stuff putting back together can be a pain. here is what mine looks under the hood. The engine bay is a little dirty, its winter out tho and i don't feel like cleaning it haha. It usually is pretty clean.