Injector Balance Rate Question

[doodad]

I've got an '03 LB7 dmax stock with 97K miles, never had an injector go bad.

Recently it's developed a knock under load 1500-1800 rpm. Checked balance rates, all decent ( -1.7 to +2.3 ) but #5 is +5 in park and up to +9 in drive, obviously out.

No fuel in oil, only a little white smoke cold, sometimes. I run good fuel w/stanadyne. Recently double dosed it to see, no difference.

I'm not sure what to do about it, likely a dealer will refuse warranty ( still on 5yr/100K to Oct '08 ) without other stronger symptoms, unless any of you can suggest a better way to communicate it.

Is it bad to run it this way?

Is there any other reason for this - other than injector?

Can anyone recommend a good diesel capable dealer near Rochester, NY?

Any ideas welcome.

Please help.

Thanks.

[DmaxMaverick]

Welcome aboard!

You have a bad injector(s). The extended injector warranty, which should apply to your truck, is 7 years or 200K. All 8 injectors will be replaced, in accordance with the bulletin. +9 is pretty far out there, for sure. The white smoke and knock is most likely related. I can't recommend a dealer (wrong coast), but if you are seeing a +9 (under any condition), it should be a no-brainer for any dealer. BTW, the cylinder with the +9 is not necessarily the hole(s) with the bad injector (not that it matters to you). The computer will adjust injection events to compensate for weak or poor injected cylinders, and a large + indicates a significant compensation. This is done to maintain a smooth and balanced running engine. You can test the "raw" injection (with no balance compensation) by applying a little throttle at idle, but not enough to increase engine speed (+1% throttle). Your balance rates should level off, and the idle should get noticeably more rough or lope. Another thing to monitor is the PWM (Pulse Width Modulation). A weak cylinder will indicate a departure from the others, usually shorter by .1 or .2 ms or more.

Good luck, and let us know how it turns out.

[doodad]

Thanks, very good info & insight.

I've read the requirements for the extended warranty and it seems to require fuel in the oil or high return rates ( which I can't tell without having it tested ) Have there been instances where just these symptoms trigger that whole repair?

I guess I am worried about an argument, based mostly on many other people's problems getting the dealer to do the right thing.

That is the other reason I'm looking for a good dealer. That and not wanting them to screw it up worse.

Also, is there any risk of damage under these conditions? Provided I'm not puking into my crankcase.

[brs954]

Here is a really dumb rewbie question... How do you check balance rates?

[DmaxMaverick]

Thanks, very good info & insight.

I've read the requirements for the extended warranty and it seems to require fuel in the oil or high return rates ( which I can't tell without having it tested ) Have there been instances where just these symptoms trigger that whole repair?

I guess I am worried about an argument, based mostly on many other people's problems getting the dealer to do the right thing.

That is the other reason I'm looking for a good dealer. That and not wanting them to screw it up worse.

Also, is there any risk of damage under these conditions? Provided I'm not puking into my crankcase.

Mine were replaced less than 5K ago. Symptoms were rough, smoky idle and knock. No fuel in oil. If your injector(s) is that far out, it will have a high return rate, if they properly check for it. With your symptoms, anything more would be a waste of time, yours and the dealer's. They may insist on it, though. Find a no-nonsense dealer that will play nice.

Light driving and "staying away" from the knock won't likely hurt anything. Towing or hard driving is not recommended. I would not drive it like this for very long, though. But, you gotta do what you gotta do. Keep an eye on your oil (level and consistency) and listen for the knock to get worse in the meanwhile.

[DmaxMaverick]

Here is a really dumb rewbie question... How do you check balance rates?

You need a Tech II scanner, Predator programmer (and possibly other programmers), or compatible Mac or Snap-On scanner (among others).

[GordonMarks]

on the 01 LB7 that I put in my Sub, I have 2(3 &5)w/neg balance rates-4, -6. I have the knock but no smoke except under full throttle. Since the engine sat for 4 yrs., I was planning on running it for 3-4 tanks w/some injector cleaner.
Any Input?
thanks.

[doodad]

To check balance rates, I use a PC based OBD2 tool I have ( if ok with forum moderators it is from Alex Peper's obd-2.com ) It, like other tools, allows me to read just about anything, but unlike the Tech2 I don't really have any control over changing things. I don't use a tuner of any sort either. I use it to diagnose, chase, and repair lots of things on my other vehicles (o2 sensors, transfer case faults, abs faults, etc.)

DmaxMav - I'm careful with running it, and I do keep an eye on things. It only recently developed, and I understand the balance rates can be even larger - but that leads to thrown codes and such. Unfortunately, it is my plow truck and we have snow again here. Just private, no accounts.

My problem is finding a decent dealer service & tech. One local shop has, according to their service writer "mechanics that work on diesels, but aren't specifically trained for it". Also, he said they haven't seen any injector issues which leads me to think they aren't very experienced at it.

I will probably just start calling around and asking if they have real diesel techs on staff, or perhaps call GM to get a referral if they would do that.

Gordon - your LB7 transplant, where did you get the engine from?

Thanks folks, I appreciate the info.

[GordonMarks]

I was fortunate enough to get a whole donar an 01 K2500. The last mileage figure available was 09/03-83K & it was totaled in 05/04-hit hard on the DS. It had been sitting a while but it was all there except the owner had cut the rear half off to get the rear. There was nothing very significant in the dealer warr. records.

[More Power]

I will probably just start calling around and asking if they have real diesel techs on staff, or perhaps call GM to get a referral if they would do that.

Thanks folks, I appreciate the info.

GM Customer Assistance does not, as a rule, recommend any dealer over another. This can lead to legal issues between GM and the dealer. However, some years ago, a member who had been a GM franchised dealer, provided some tips on locating a dealership qualified to do an expert job repairing a GM diesel equipped truck. He said:



There are other ways to discover which are the leading GM or Chevrolet dealers for truck sales in the fellow's region, with or without the help of the factory. Use the yellow pages, and locate the available Chevy (or GMC truck) dealers, then call and ask the Service Manager how well his shop does on Diesel products. Be up front, he deserves to know that he'll be helping the customer from hell, who's driving an unrepairable lemon. A good manager will not waste his resources getting an already disgruntled customer to go ballistic. A good manager may say that his shop is strong or weak on diesel. Only an idiot would gleefully invite someone in who he could not satisfy. SPEAK to the service manager before making an appointment. Do not rely on the advice of an assistant service manager or service writer (who's goal is to sell parts & labor hours). Talk only to the service manager because he will want to use his resources well.

[doodad]

Yeah, I didn't think GM would, good point.

I've had luck complaining to GM about my neighborhood Chevy dealer and getting them to authorize Chevy warranty or campaign work at the GMC dealer who is much more service oriented.

When I talked to them this time, though, they said even though they will do the work on a Chevy, they get some extra paper/hoops to jump through. I can pay them to work on Chevy, and I do, but don't want to burn them doing my crazy warranty work.

I have an oil sample out for analysis, should get the results tomorrow to see if there are any traces of fuel in the oil. THen I plan I calling, and your posted advice makes sense - go right to the service manager.

That and my balance rate is drifting up slowly, #5 is 5+ in park and over 10 in drive.

Thanks always for the suggestions and info. I appreciate it.

[doodad]

Just got my oil analysis back. I am lucky, I have NO fuel in my oil. Now I just need to get this thing diagnosed and fixed. Darn thing is starting to sound like a Cummins, and that is unacceptable.