Oh boy.... Went to the Super Target this evening. Truck ran fine on the way there. Go in for about an hour. Come out and start her up.

She starts idling really rough. I mean the whole truck is shaking. If I just touch the throttle, she smoothes out. Let off the throttle and she's got the DT's again. I drive a little ways, pull off into another parking lot and turn her off. I let her wait for a few minutes and re-start her. She's still idling rough. I take off again for home and decide to give her a good blowing out (after she gets up to temp). Acceleration is OK but not as hard as I remember, lots of smoke.

I get to the house, pull into the garage and roll the window down. She's still shaking and it sounds like I've got a nice knock going on.

I'm thinking injectors.... but I was wondering if anyone else has had similar symptoms and the fix was something else besides injectors.

Here's some background on the truck: 2003, ZF tranny, 25000 miles, Fuel filter changed every 10000, Oil changes every 6000. Oil level is full, no changes since I last checked. I use Power Service additive. NO MODS. No secondary filtration (probably should have, huh?).

I searched the site for more info, but really could not discern much from the search other than injectors.

Thanks

Bad vibration at idle, crank case full of fuel...cup seals on 2 injectors and a return line leaking truck had 800 miles on it. Now has 15k no problems...

Dirty air filter....?

Marry Xmas!!!

See truck down section, under knock and smoke. Might be bad fuel?

Here is something to consider, I have seen your complaint several times lead to this...

6.6L (LB7) Engine Vibration, Misfire, Rough Idle , and No DTCs - kw contaminated contamination diesel flywheel foaming fuel idle leak manual miss noise odor smoke vapor vent #PIP3239 - (Nov 16, 2004)

6.6L LB7 Engine Vibration Miss or Runs Rough, No DTCs

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When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.

<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1566270#ss1-1566270">Condition/Concern:

6.6L (LB7) engine vibration, misfire, rough idle, and no DTCs.

<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1566270#ss2-1566270">Recommendation/Instructions:

<LI type=1>Verify the engine has the correct oil level and check for presence of diesel fuel in the engine oil. If diesel fuel is found in the crankcase, complete SI diagnosis for fuel leaks inside of engine. <LI type=1>If DTCs are present, complete the SI diagnostic chart for the DTC found. <LI type=1>Use the Tech 2 to monitor the cylinder balance rates. If balance rates are excessive, complete The SI diagnostics for "Fuel Injector Balance Test with Tech 2". <LI type=1>Check for loose or missing torque convertor bolts. NOTE: DO NOT RUN ENGINE WITH THE TRANSMISSION TORQUE CONVERTER REMOVED. THIS MAY SHEAR THE CRANKSHAFT BALANCER PIN. <LI type=1>Inspect the engine mounts and accessories for any ground out conditions. <LI type=1>Remove the accessory drive belt and evaluate the concern. <LI type=1>Remove the crankshaft balancer assembly and inspect for a possible sheared or damaged crankshaft balancer alignment pin. The crankshaft balancer assembly may rotate on the crankshaft and cause an engine out of balance condition. Verify the crankshaft balancer is torqued to the proper SI specification.
If the vehicle has a manual shift transmission, SI diagnosis is inconclusive, and the above suggestions do not lead to a repair suspect a Dual Mass Flywheel imbalance. A Dual Mass Flywheel imbalance can cause abnormal injector balance rates, excessive engine rattle noises, and excessive shift lever vibration. Replace the Dual Mass Flywheel as needed.
Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance. This diagnostic approach was developed for the vehicle with the VIN you entered and should not be automatically be used for other vehicles with similar symptoms.

<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1566270#ss3-1566270">Models

(01 02 03 04 LB7 C2 C3 K2 K3 Chevrolet Silverado and GMC Sierra GMT800) and (03 04 LB7 C4 C5 D4 D5 E4 E5 Chevrolet Kodiak GMC Topkick GMT560)

She's in the shop right now. Hope to hear something this afternoon.

As far as the air filter is concerned: I changed it at 20000mi and verified the 'sight glass' as ok.

As far as fuel contamination is concerned: I've been running it for a week since the last fill-up. Wouldn't bad fuel show up almost immediately?

Max may be on target... It could be the dual-mass flywheel and not injectors. I've heard a chirp or two from it recently....

Anyway, I'll keep everyone posted on the diagnosis/fix...

L8r

Good News!!!!

There must have been a gremlin in the system. The techs spent all day looking, poking, monitoring, test driving, etc. and the problem is just gone. When I took it in the truck was still shaking in the service drive (although not as bad as the previous night), but by the time it got into the shop, she was purring like a kitten.

The techs checked balance rates, command fuel pressure tests, return flow test, and fuel quality tests... everything required. All parameters were normal.

The shop foreman, who I personally know, even took a look at everything. He knows that I rarely bring a truck in without knowing what's going on.. and I very rarely just leave it there. He could not find one single thing wrong. He did say that if it did it again bring her back in, find him immediately and don't turn her off. He also offered the use of a mobile vehicle recorder.

Anyway, I picked her up last night at 6:30 and they bring her into the service drive. She's idling in the drive and running as smooth as a baby's butt in a messy diaper.

Hopefully it was just a gremlin...

L8r..

Question....
Did you have your truck plugged in before this happened?
Reason I asked is that everytime I plug my truck in she will do the same thing.
When I start her up first thing that morning everything is fine. Drive to work and all is fine. Go to lunch and she is shaking and rattling. Leave for home and she is still shaking and rattling. If I do not plug it in that night then she runs fine. I have been chasing this for a couple of weeks.
The temps have not been that bad. 30's at night and 50+ during the day.

Mike

Mike:

Don't plug her in any more... She sleeps in a garage.

Leaving Target that evening, the truck had been sitting about an hour in the parking lot, temps in the 50's.

The next morning's start was after an overnight cooldown in the garage.

Both times she had the shakes...

I'm confused as the shakes have disappeared:confused: The shop tested every parameter and found all to be normal.

So... I just gonna drive her as normal. If it does it again, it's back to the shop..

L8r