Truck's Running Rough

[zoso59brst]

The Kon has been running a little rough lately. Today I got my butt out of bed early to beat the t-storms and did the obvious: plugs, wires, air filter (swiss-cheesed the box while I was at it.. wow!) and did a Seafoam treatment. It was the first time I seafoamed the truck and I got full on you-tube smoke it was great. Also cleaned the MAF.

Truck does feel better now, but still idles a little rough. I cleaned the TB a couple months ago when I was having some high idle issues and that was resolved, but now I don't know what else to check. I did not do the PCV valve because in the 2 seconds I looked for it I couldn't find it, and was getting lazy after doing plugs and such. That being said, I only seafoamed into the brake-booster line.

Any ideas? Thanks all

 

[TheFuzz]

Maybe a vacuum leak somewhere? More info on the nature of the issue - describe how it sounds. Sputtering, missing? At idle or at speed? Is it constant or only at idle or certain speeds? PCV valve should be located on the rear of the driver's side valve cover, there is a hose running from it to the middle of the intake manifold, on the top. The hose pulls upward out of the valve cover and the PCV valve itself is attached to the hose. It pulls right out of the hose, takes 15 seconds to swap out. While your in there, get some starter fluid and spray around the intake manifold and listen for a change in idle to check for leaks, you could have a leaky gasket. Common issue IIRC.

ETA - what kind of gas are you using? Could be a bad batch of fuel, maybe try a bottle of Lucas in the gas tank. That stuff works wonders kinda like seafoam does...

 

[zoso59brst]

Maybe a vacuum leak somewhere? More info on the nature of the issue - describe how it sounds. Sputtering, missing? At idle or at speed? Is it constant or only at idle or certain speeds? PCV valve should be located on the rear of the driver's side valve cover, there is a hose running from it to the middle of the intake manifold, on the top. The hose pulls upward out of the valve cover and the PCV valve itself is attached to the hose. It pulls right out of the hose, takes 15 seconds to swap out. While your in there, get some starter fluid and spray around the intake manifold and listen for a change in idle to check for leaks, you could have a leaky gasket. Common issue IIRC.

ETA - what kind of gas are you using? Could be a bad batch of fuel, maybe try a bottle of Lucas in the gas tank. That stuff works wonders kinda like seafoam does...

It's not too vocal about it. More of a random vibration and only at idle.

Thanks for the info on the PCV. Do you think it's worth another sea-foam through the PCV line? And if so, will I foul my brand new plugs by doing so?

I only use Shell, BP, or Exxon fuels, preferably Shell when possible. This has been going on for a while now, so bad gas should be out of the equation. I fed the rest of the Seafoam bottle to the tank, so if that doesn't help I'll try the Lucas next time. Possibly fuel-filter? Pump is brand new.

I'll check for a manifold leak as soon as I have some time.

thanks!

 

[zoso59brst]

I cleaned the TB a couple months ago when I was having some high idle issues and that was resolved

Aaaaaaaaaaaaaaaaaannndddd it's idling high again

 

[dwmmatt23]

did you check for an air leak? does it do it at all times?

 

[zoso59brst]

did you check for an air leak? does it do it at all times?

Not really. For some reason I don't suspect that, but maybe that's where I'm screwing up. Yeah it's pretty regular. Haven't had a nice smooth idle for a while now. If I had to pick something, I guess it feels more like a miss. But it's not enough to be obvious or even see on the tach, it's just enough to piss me off lol.

 

[TheFuzz]

Hrm. Interesting, especially with the high idle coming back. You said you just replaced the plugs, was the truck doing this before or did you replace them in an attempt to solve the issue? What kind of plugs? Did you replace the wires too?Have any codes been thrown by the truck? When you cleaned the TB, did you remove it? If you did, did you replace the gasket? I still think it's a mild vacuum leak but I'd have to hear it to get a better idea...

Try cleaning the MAF sensor if you haven't done that yet, you'd be surprised what kind of hell that little bastard can cause when it acts up. Use MAF-specific cleaner spray though, no brake cleaner or TB cleaner or you'll destroy it. And yes, I'd seafoam again through the PCV line. It's the best way to make sure that the seafoam is getting to all 8 cylinders. Fouling is a concern, but pretty rare among these trucks.

Edit - just re-read your original post and saw that you cleaned the MAF. Disregard that part.

 

[puckhead]

Is it still giving you troubles? A while back mine was running real rough and it ended up being the egr valve. They can stick open sometimes when there is too much carbon build up. Might be worth a check if you have gone through all your other options.

 

[zoso59brst]

Hrm. Interesting, especially with the high idle coming back. You said you just replaced the plugs, was the truck doing this before or did you replace them in an attempt to solve the issue? What kind of plugs? Did you replace the wires too?

The high idle now appears to have left as fast as it returned... I did the plugs mainly because they were due, but also in hopes of it smoothing things out. Plugs are NGK TR5's which I had read good things about on TYF, and wires are the good delcos. I will start checking for vac leaks on my next day off as well as seafoam through the PCV line.

---------- Post added at 12:06 AM ---------- Previous post was at 12:03 AM ----------

Is it still giving you troubles? A while back mine was running real rough and it ended up being the egr valve. They can stick open sometimes when there is too much carbon build up. Might be worth a check if you have gone through all your other options.

That's a good thought too. Can the EGR be cleaned or it has to be replaced?

Speaking of carbon build up, one of the heat shields on the plug wires I took out was really cooked looking. I will try to get a pic. Can a heat shield arc? I've never seen that before.



Thanks again for all the help everyone - this place is great.

Pete

 

[puckhead]

The place I took it to said that it can not be cleaned but it can. I think you can also get rid of it too, dont know how though. Probably something in the computer.

No idea about the heat shield arcing though. Let us know what you find out!