Engine Surges During Idle

[First]

Gentlemen,

My '02 Duramax has been surging during idle for about 3 months and is now getting worse. Any ideas as to what may be causing this? It runs fine on the open road, but at idle the rpm's go up and down slightly.

First

[More Power]

Many feel a faulty FPR (Fuel Pressure Regulator) is the primary cause of idle surging. Many of these engines have done this. GM issued a service advisory some years ago, and indicated that unless the idle speed variation was 100-rpm or more, they would not perform any corrective measure to solve the problem under warranty.

Lots of info about idle surging can be found while using the search feature here in this forum.

Jim

[First]

Jim,

Thanks for the information. I think you hit the nail on the head!

Scott

[THEFERMANATOR]

Get a scanner and watch the desired and actual fuel pressure readings. They should be within 200-300 of each other. If the actual varies alot then most likely the spring in your fuel pressure regulator has broken, or the plunger has scored the bore and is sticking. This is a fairly common issue on LB7's and even LLY's. HUCKSTORF DIESEL has the best prices I've found for a new one.