I have a 2004 lly with no mods. I have noticed that at 1000 rpms it has a definate surge to it. For awhile I thought it was just me but it is definately surging. I made an appointment with the dealer for Monday. I would like to go in with as much info as possible. Could this be injector trouble or do I need a reflash or somthing else. I just want it fixed and want to make sure I say the right things in order to get it taken care of. One other thing when I am at full exceleration(WOT) the sound of the engine changes drastically don't know how to explain it but it kind of sounds like a gasser that is low on oil or somthing could this be related? Thanks

Believe that there is a reflash update for LLYs if you haven't already had one. As for the other question, does it sound like a knocking/pinging like a gasser on low octane or need of a valve job? My LB7 did/does that sometimes. Sounds like I'm floating a valve or something.


Let us know how it goes at the dealer......


LATER!

I had almost the exact same problem with my LLy, the 1000 RPM surge.

Dealership checked the injectors and found #3 balance rate was out of spec.
They installed a new injector and problem is fixed, so far. :blahblah:
There are alot of posts regarding the surge problem with the LLY's.
I also had the dealership re-flash the computer with the newest software. They said my ECM has the most current version.
If you truck was purchased before September, or hasn't been in since then, it probly needs the re-flash.

There is a TSB about this issue, but I forget the number right off hand.
Good Luck.

bodysurfer yes it sounds exactly like a gaser that is floating a valve I just wondered if this was normal or if there might be a problem possibly linked to my 1000 rpm surge does anyone know? So I should have the dealer check my balance rates or just have the reflash first?

that update fixes a couple issues..surging, injector rates..

here is the PIP for the first update. I think there is another one newer to this one. Mine was flashed with PIP3129B

Good luck

04 6.6 LLY Smoke , Fuel Knock , Surging and High Injector Balance Rates - kw white black idle surge rough noise accelerate P0300 P0301 P0302 P0303 P0304 P0305 P0306 P0307 P0308 miss misfire SES DTC #PIP3129 - (Sep 10, 2004)
GM document ID# is 1549221
04 6.6 LLY Smoke, Fuel Knock, Surging, and High Injector Balance Rates
.

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.
Condition/Concern:

Customer concern may be a low speed surge (8 to 10 mph or near 1000 RPM), acceleration fuel knock noise at 1500 to 1800 RPM, rough idle, white smoke at idle, or high positive injector balance rates.
Recommendation/Instructions:
1.
2. High positive injector balance rates (over +4.0 in park or +6.0 in drive) may be causing white smoke at idle or while driving.
3. Document all injector cylinder balance rates at the beginning of the diagnosis.
4. There is an updated calibration to address the white smoke, high positive balance rates, idle surge, and a fuel knock noise at or near 1500 to 1800 RPM.
5. Install the updated calibration and evaluate the smoking, high injector balance rates, idle surge, and fuel knock noises.
6. If there is still a mechanical concern with an injector, and balance rates are still over the SI specification of +4.0 in park or +6.0 in drive, replace only the effected injector.
NOTE: Before any injector replacements a large fuel sample should be taken from the fuel filter and checked for contaminants or poor quality.

briano, do you kow if they have the same for an 05? my cousin's 05 has similar issues and we are about to bring it to the shop. he only has 8k miles on it. i checked the balance rates and injectors 4 and 7 are above +4.2 mm, while in neutral with the emergency brake on. they seem to be getting worse from when i checked them a month ago. now it may be the injectors going out, but i don't know if there is a flash for the 05's yet. my 04.5 lly has yet to have an issue for 83k miles now.

any info or advise will be good.

only info is from what I have read from other members, but some 05's did not have the latest code like everyone thought.

best thing is just take it in for those exact symptoms and sort of persuade them towards the flash update. Their may be a newer one out, the one I posted is the first one.

cool, thanks

If someone has a cure for the low throttle surging onthe LLY (approved by GM or not), please post. To date GM doesn't have a fix for everyone.

Got mine back from the dealer yesterday. I knew I was in trouble after the first sentence out of the techs mouth. He said he was not aware off the low idle surge problem and didn't find any service bulletins either. I told him I had it in my back pocket if he would like to see it. He read it and said well if it injector trouble you will be ok for 200k that is how long the warranty is for. I told him that was for the 01 and 02 only and not for my 04 and he said he wasn't sure. Mind you this is the guy that the service manager told me was their "dedicated diesel guy". On the way home after it had warmed up it surged all the way up my driveway this time at about 1200rpm rather than 1000. The tech said he checked the balance rates and the worst one was +1. He said he updated the computer with the latest reflash. The copy of what he did shows three different flashes for low idle surge and he put all of them in. My question is did he just write over the first two he put in and I only got the one. Seems to me there should have only been one update for this problem. I hope this is making any sense to you all. Does this sound right I can post exactly what he did if it would help.

roy - get a service advisor and tech that cares about their customer. This guy seems to be giving you any answer that he thinks will stick. No-one mentioned the valve noise pinging sound you get at WOT. Its nothing to worry about, its when the pilot injection turns off right at 2500 rpms. they say this pilot injection is what makes the dmax so quiet.

My dmax surges a whee bit but Ive learned to deal with it. I know its not the answer your looking for but do a search and youll find GM doesnt really have a cure, so instead of banging my head into the customer wait lounge 2 times a month, I live with it. good luck

Thanks dentman I guess I will live with at least for awhile. It doesn't seem to bother it performance whise or anything although I do wonder what effect it might have on fuel economy and how much stronger it might run. It just bugs me that I spent this much money for somthing that isn't 100% right. If the knock or ping I am hearing is my pilot injection going off then what are they calling fuel knock and when would it be noticeable?

well, Im going out a little here so confirm this before you move forward, but I would guess that if whoever told you that the fuel knock is the noise you hear, and the pilot injection is a fuel delivery issue, then they are the same. Do this, go ahead and do a little testing to see when your anomoly happens and record the conditions. If it goes off right ( or noise starts as the case is) about 2450-2500 rpm... then Id say they are the same.