I have 2k miles on the truck and LOVE it so far except for two minor problems. One is the front end rattle/clunk at slow speeds over rough roads. The other one I just noticed pulling my boat up the ramp I get a slight surge around 12-1300 rpm's, not a big deal but I'm gonna get them to check it while they have it for the front end noise. Aside from that I've pulled my boat (4000# Center console, more wind drag than weight) over 700 miles and was very satisfied, no comparison to the Z-71 w/5.3 I sold.

I talked to the service dept. this morning and he said no problem, my suspension man will take care of it, he doesn't know about the surge yet because I thought it was a one time thing. I don't notice it under normal driving conditions but i noticed tonight that I can duplicate the surge in the driveway by holding the brake and taking it to 1200rpm's, if I go to 1400rpm's it smooths out.

I had the same two issues on mine. A reflash and intermediate steering shaft later, and now my DMax is trouble free.

There is a bulletin for the surge issue, they reflash it which fixes 60% of the trucks the other 40% they don't yet have a fix. They surge form 900 to 1300 rpm's. Mine is really bad, the reflash changed the rpm from around 900 to 1100 on mine so now it does the surge driving between 25 and 30 mph. GOOD LUCK!!!

I had the same clunk sound that sounded like a loose shock mount or something from the front end...Turned out to be the hood stopper on the drivers side had gotten loose and spun down. One other guy on the forum had the same sound and told me about the hood stopper. I think he said he used a 10mm nut to hold the stopper in place with.
I will also get the surge every so often at low speeds, took it to the dealership and they told me that it was normal. When I asked if they could re-flash the computer, they told me that I already had all of the updated flashes. HHMM....Good luck!, Matt

I have 25000 miles on my 2004.5 and it just started the surge thing. Only mine seems to be at idle as well. Are you guys having the same problem or is it only at low speeds. Will the reflash affect other things as well. Other than the surge, which is not all the time, I'm happy with the way the truck runs. My mpg is good and I don't want to mess that up. What do you think? Should I see about the reflash? Mine's an early 2004.5 and I'm sure it is not current. Or is this surge problem an Edge Juice thing?

Thanks :o:

I can't give an opinion on whether it is an edge/juice thing or not...I dont have one. I would think that if it does it at idle that I would take it to the dealership and get it flashed.
Even though they told me that the surge was normal at low speeds, I still think that was a copout and they dont know why it happens! I figure I can live with the surge until it happens at idle or freeway speeds, then that sucker is going into the shop!

I just got my truck back from the dealer. They did all the latest flashes on the computer which didn't help at all. As far as the front end noise the guy said "we drove it, no problem found." So needless to say I'm a little pissed, and it didn't help any for the service manager to say "that's a characteristic of Duramax," and a salesman (not mine) say "they have some quirks you have to get used to." They now are contacting the head Diesel mech. for the area to see what if anything can be done. So, I was in my car following my NEW truck home and noticed that it smokes more than before, even at idle a light but steady flow of blue/black smoke out the exhaust.

I guess most people would say I'm being overly picky, but I think I have the right with a 50k truck, and to say we can't fix it so you'll just have to get used to it is the wrong answer. I would be out of business if I pulled that crap with my customers!

I can't believe I'm saying this but I'm starting to wish I'd kept my Z-71 5.3, and I haven't even had the truck a month yet.

You may have what is similar to the "lopey idle" that some experienced with the LB7. Some have had it clear up by adding a cleaner and lubricity additive. Stanadyne lubricity formula would be my first choice and it is recommended by gm (listed in a service bulletin - so you are "safe" using it as far as GM is concerned). I inferred that the lopey idle was caused by a sticky fuel pressure regulator and the additive cleaned and lubriciated this fuel system component (as well as the pump and injectors).

Fuel in the u.s. does not meet european standards (and what bosch recommends for our fuel system) and won't come close until later this year when the new U.S. diesel fuel spec is fully enforced. Until then, it's safest to add stanadyne lubricity formula to every tank. I bet that if you add this or some stanadyne performance formula that your issue will go away.
...if not, you might just have a bad tank of fuel, or worst case - a bad injector.

- jeff

The noise from your front end is probably what is referred to as "steering shaft clunk" - there is a TSB to replace the steering shaft...

Clunking Noise Under Hood and Can be Felt in Steering Wheel (Replace Upper Intermediate Steering Shaft Assembly) #00-02-35-003H - (Apr 19, 2005)

This is listed in the TSB section of this website. This doesn't apply to your truck, but the issue is always resolved by lubricating the steering shaft. Just tell the service advisor that you have the "dreaded steering shaft clunk" and that you want it lubricated on your next visit - it is an annoyance, but isn't an issue in terms of front end wear, etc.

- jeff

Thanks Dmax. The surge has been there for a few tanks from different stations so I don't think it's bad fuel. I have some power service that I add to my TDI VW, is that OK? If not I will get some of the stanadyne and try that. Next time I'm there I will get them to lube the shaft also and see if that makes a difference.

A reflash started my surge'n! I'm one of the lucky ones and was able to unplug my EGR with out a code. Guess what? My surge'n problem went away when I unpluged the EGR! Imagine that!:exactly:

The lopey idle thing can build up over time and is cleared up by additive (most of the time)...

I prefer the stanadyne - the responses that I have seen from power service posted here set my b.s. detector at "full tilt". I am sure the P.S. would be fine for one tank; For regular use, I would go with stanadyne lubricity formula (highly concentrated and cost effective) or the new chevron delo stuff. The delo injector cleaner/additive comes in two flavors - one has a cetane booster; I would go with the non-cetane boosting one for the summer months. The cetane booster can destabilize the fuel if you over-additize with it.

- jeff

I should add that I only have 2k miles on the truck. I will however look for some stanadyne. That is interesting that bypassing the EGR stopped the surging...(for testing purposes only).;)

speedrcr, see my thread Engine Surge. With only 2000 miles I doubt your problem is caused by the same thing as mine. I have 24000 miles but it might be something to look for.
:help:

I just read your post and will check that in the morning. Interesting thing is while I was looking at the engine this past weekend the harness and wire tie you described caught my eye. I was thinking that it had a cheap look to it.

Mine purrs like a kitten now!!!!
:cool2:
Good luck.

I just took my 05 DMAX in for a clunking noise coming from what I thought was the inter-steering shaft but come to find out it was the nerf bars. Did a slight adjustment so there was no metal to metal contact and all is good! Hope that might help someone out!

The surge problem is in the LLY, mine is an 04.5 started surging around 18k miles GM has a bullitin out that says 900 to 1300 RPM surge. If the PCM has the latest update DO NOT ATTEMPT TO REPAIR GM TECH IS WORKING ON TRYING TO FIND A FIX!

Needless to say they have not found one yet. I have been after GM about this since April.

That's all they did was install the latest updates which made no difference. The clunk is still there and I haven't installed the bars yet. It seems worse at around 30-40mph over a slightly rough road, you can feel it in the steering.

This sounds crazy but my mileage seems to be down since the reflash.

Check the hood stops!!! I already posted earlier that mine was making the same noise and found that the hood stops had loosened up...Give it a try MAN!!