Well I dont have much to go on but a list of symptoms. Done a lot of rough idle searches and whatnot. Really looking for advice and experience. My truck has about 185k and generally runs an economy tune from my bully dog power pup. In my history u can see ive been having some problems. My injector balance rates are wacky to say the least with the number 8 cyl showing a solid positive 15ms. No fluctuation. The truck is doing the typical crank case vent smoke in headlights at night thing, along w a crankcase type odor that can be smelled in the cab w the ac vents running from outside air. To make things even crazier, it has an intermentent rough idle. Sometimes more prominent than others. Some days not at all, although fewer and farther between lately. Wanted to do a compression test, but as luck would have it the number 8 glow plug snapped and attempts to remove have been futile. My last chance will be welding a nut to it a praying. lol. Short of getting the plug out and doing actual compression test, i have a few concerns. I dont mind puttin money into it, just dont wanna waste it. Obviously it needs injectors, and probably head gaskets. No prob. Just make me sick to spend the time and money to do that and still have an issue. Anyone w any experience like this? Thanks for all the help as always. Sorry for the long post.

I also wanted to add this strange symptom. At times, the rough idle described is much more prominent when braking to a stop. When this is happening, the rough idle is much more prominent then when the vehicle comes to a complete stop. Even on a slow rolling acceleration from a light at times. Very strange. Anyone?

Are you sure you FPR isn't going bad? just a guess

Are you sure you FPR isn't going bad? just a guess

Thanks for the reply! No, im not sure. However my truck is not doing the typical surge that indicates a FPR. It will be one of the things I replace when I do the injectors. Just to be safe. Any other ideas? Really has me baffled w some of it.

I have a bad fpr and it gives me all of the above symptoms except for bad balance rates.

I would say FPR also, mine does it slightly every so often, sometimes tuning will cause this also.

It's sounding more and more like the smart thing to do would be headgaskets, injectors, cups and fpr. wow.. Should be a fun job. Of course while i have the heads off ill have them checked and the glow plug taken out. Probably about to crush 4 grand. Just really hate to be wrong when I can get a GM reman motor for 7500. What to do , what to do? lol thanks all!

Keep us updated as to what you finally have to do to correct your problem(s).

since you are going to have it all pulled down and replacing it anyway you may want to think of putting a new IP on it instead of just the FPR. your replacing everything else might as well.

After a phone conversation with a member who's had pretty much the exact same symptoms, i'm pretty convinced that an injector cup has lifted. Rather than tear the heads all the way down, I think ive decided to replace injectors and cups. I assume that upon further inspection ill know more. But it makes sense to me that an injector cup could cause most if not all of my problems. Anyone?