Duramax Surging

[First]

Gentlemen,

I have an '02 Duramax that has always surged slightly in RPM's when it idles, but recently it has become more annoying. The engine is now surging to the point that if I don't keep a hard brake pedal the truck wants to leap slightly. In fact when the engine does this it actually shutters a bit, almost like a miss in the engine. Has anyone else experienced this and if so how can I fix it? Thanks,

[More Power]

Searching for the keyword "surging" in the Duramax 6600 forum should produce quite a few threads.

In general, it's likely due to an inadequate Fuel Pressure Regulator (FPR). This is a replaceable unit on the back-facing surface of the high-pressure Bosch fuel injection pump.

My 2001 has done this for years. It never gets worse, and it's not been a big enough of a problem to warrant FPR replacement. It seems like a fuel treatment with a lubricity additive or a little ATF helps, but it's hard to know for sure.

Jim

[First]

Thanks Jim. Would that also be related to the engine shuddering? It has always surged a little, but now I have the shuddering that feels like the engine has a vibration that comes and goes throughout the idle... It's very slight, but obviously present. Thanks, Scott

[DmaxMaverick]

Check the oil level and watch the oil pressure. Fuel in the crankcase will do the same thing.

[First]

I thought of that because I went through the injectors leaking into the crankcase about 7 years ago... So two days ago I checked the oil and the level was fine, in fact it was almost due to be changed so I did that the same day. I haven't seen a change with the engine shuddering at idle and I'm really starting to get concerned it may be an injector problem. The injectors only have about 60k miles on them, but I'm still concerned... I really appreciate all the input and advice. -Scott