Lopey idle & dealer recommendation

[RDH]

I have a 02 GMC D-Max sold in April, 02.It now has about 16K miles & has developed the lopey idle. I know this subject was heavily discussed some time ago, but I didn't pay too much attention because my truck didn't have the problem at that time.What is the fix for this problem, & what GMC dealer in the greater San Jose, Ca. area is the best qualified to do the work. Thanks in advance. Bob

[mdadgar]

I use Moore GMC in Los Gatos. I'm not sure about their level of Duramax expertise (although the Service Dept Mgr has one) since my truck has had no serious issues, but their customer service is second to none.

I'd recommend them.

- Mark

[More Power]

Idle speed variations can be as high as about 100 rpm before a GM dealer can declare a problem. If a re-flash of the ECM with the newest code doesn't solve the problem, you may need a replacement fuel pressure regulator, which is part of the Bosch high-pressure fuel injection pump.

This problem has been increasingly less common, but it can appear even after the engine is out of warranty. I answered an email a week or so ago from a member with 225,000 miles on his Duramax. His began exhibiting a lopey idle, and a new regulator solved the problem.

MP

[Kennedy]

Assuming it is a warm engine lope, it is likely the Rail psi regulator.

If you are using libricity additive, it may be a good idea to stop until it is replaced. I've had cases where FPPF Total Power helped, and masked the problem for quite some time. Eventually, it resurfaced, and discontinuing the additive temporarily aggravated the lope enough to meet the "fail" specs.

[RDH]

I forgot to mention,it's a cold idle lope. I talked to Stevens Creek GMC & they admitted not too many diesels came thru there. Will the dealer do an arbritrary ECM reflash to update it? Thanks, Bob

[More Power]

RDH,

You should request that the ECM be updated with the newest program updates. The dealer service department should know that this is the first step, but I'd still ask anyway.

If the lopey idle isn't resolved with an update, then you can consider a replacement pressure regulator.

MP

[Ed McFarland]

I took my truck to the dealer for this problem. He reflashed the ECM and the lope was still there, he said the Fuel Pressure Reg would cure the problem in some cases and wanted $685 to replace it, I passed on that solution unless the lope gets worse. They said mine was only about 75 RPM

[DmaxMaverick]

It seems to me this problem should be included in the 100K warranty. It is.

Don't let them tell you different!

[Kennedy]

Originally posted by RDH:
I forgot to mention,it's a cold idle lope. I talked to Stevens Creek GMC & they admitted not too many diesels came thru there. Will the dealer do an arbritrary ECM reflash to update it? Thanks, Bob Typical word is: Reflash for cold lope. FRPV for warm lope.

[Kennedy]

[quote]Originally posted by Ed McFarland:
[b] I took my truck to the dealer for this problem. He reflashed the ECM and the lope was still there, he said the Fuel Pressure Reg would cure the problem in some cases and wanted $685 to replace it, I passed on that solution unless the lope gets worse. They said mine was only about 75 RPM

[Greg McCall]

I'm guessing from no entry in your signature that you do not have Quads Stealth 215hp tune.
It has a very lopey cold idle.

[Ed McFarland]

Thanks Guys for the info.
Ed

[More Power]

A 75-rpm lope may not be covered under warranty. GM indicated some time ago that a 100-rpm idle fluctuation was their threshold for a warranty repair.

I've yet to hear a Duramax with a perfectly flat idle rpm. Most normal cold idles are a little more unstable than a warm idle, but they all seem to vary a little.

Most cold/warm idle lope reports I remember hearing about (that resulted in a warranty repair) were closer to 200-rpm, which is very noticeable and somewhat disturbing to owners.

MP

[RDH]

Thank you all.I'm going to monitor the idle variation. Just got back from Hot August Nights. Had a blast. Everywhere I look I see more Duramax's. In fact,it's rare to see a 2500 gasser. Bob