When to change injectors

[deerhunter7]

My 2002 is smoking at idle and mileage is down about 2 miles a gallon. Seems to run ok otherwise. Can hear a miss once in awhile at idle. And are remanufactured injectors as good as new ones..?? 98 ,000 on engine. Have added Racor Fuel filter at 19,000 and use fuel supplement

[Mark Rinker]

(...from Elk River, MN)

I'd take your truck to Miller Chevrolet first, and have them diagnose. Ask for Service Advisor Wade Hanson, tell him Mark Rinker sent you.

Don't forget that you might be experiencing a common LB7 injector wiring harness issue...with the low miles that you have on, I'd rule everything else out first, before assuming bad injectors. Unless you have oil dilution in the crankcase, or a fuel knock (excess fueling, ill-timed introduction of fuel into cylinder, etc.) the problem may be elsewhere.

[deerhunter7]

That would probably be the thing to do . Would be lot cheaper than injectors. Live in Hassan soon to be Rogers..Thank-you. No Dilution or knock .

[Flyboy]

My truck is doing the same thing with 134,000 mi. on original injectors. Please post your findings when you have it checked. Thanks
Gerald

[deerhunter7]

Have appointment Thursday to get the low down . He said they have had trouble with #2 and #7 harness . Will find out what the problem is when they do their testing.

[DmaxMaverick]

The injector harness issue is unique to the LLY engines, 2004.5 - 2005 models. The LB7 has no such "common" issue.

Your issue sounds like injectors. No doubt. Keep an eye on your oil level.

[Kennedy]

Actually, there have been LB7 harness issues, but few/far between. Way back forum member Maverick (I believe was his handle) from Wasilla AK had an issue that turned out to be loose nuts on his. Since then I have encountered a handful or so. I think most of tehse are from being serviced and overlooked on final assembly. Mav's was new as I recall. Either way, these show as a misfire.

With the LB7 smoking it is undoubtedly injector related. What you want to watch out for is how much money you intend to diagnose something that at arms length is obvious. Before dropping off I would request an estimate in writing if the diagnostics will go past say $100.

I just spoke with a fellow nearby that paid as I recall $550 in diagnostics only to be told that his injectors were bad and that the Special Policy did not cover his particular mode of failure. To add insult to injury, the Tech showed him the grit in the inlet bowl of an injector. He claimed that this was from inside the fuel lines/rails as he has seen it "pounded" into the injectors. Customer was too smart for that and welcomed my confirmation that the rust WAS external then BECAME internal when the line was removed.

Spring is the plan for this fellow to bring his truck here for injectors WITH all 8 new hard lines as there is no way to properly clean the lines between the tube and nut.


On another note, I have another local customer with a smoke and knock issue. I diagnosed his to be #8 by isolating this cylinder with the Tech 2. He has replaced this single injector (and line) against my advice to do all 8. He has budget issues as I'm sure many can relate and needed his truck fixed. We'll see how this one pans out. He's due in today for a quick scan to figure out why he is in limp mode after they made the repair.

[deerhunter7]

I want to make sure it is the injectors and not a harness issue. I would hate to put in 8 injectors and find out I have not gained nothing because it was somthing else. Lots of money to guess..

[DmaxMaverick]

The possibility of a "harness issue" is NO MORE COMMON than any connector/harness issue in ANY other vehicle, or any other vehicle system. The harness issue Mark suggested it UNIQUE to the 2004.5-2005 LLY engines, when the #2 and/or #7 injector harness fails. This is a known issue and there is a TSB to address it, and it is not/can not be the same for an LB7. If you have a harness issue with your LB7, it will be rare and in no way related to any commonly known issue. This does happen, but only because it happens in all vehicles from time to time.

Smoking at idle with a miss is most likely injector(s). Check your oil level often. An overfull crankcase will also cause rough running (perceived as a miss), due to the elevated crankcase pressure and imbalance. There are other possible causes, but they are common to all vehicles on the road (fuel quality, climate/temperature, filters, emission system, etc.).

[Kennedy]

Like Mav said if it were a harness issue (rare) it will generally give a miss and set a code.

The 2002 with the bad injector (now replaced) just left here broken hearted. I immediately noticed the dead miss this time that wasn't as bad before. Did a bit of poking around and found that it smoothed out above idle, but we had some sort of phantom vapor from up front that showed up when I brought the RPM up. Pulled the oil fill cap and puff puff puff.

This one was scary to hear run when he brought it for initial diagnosis and I advised not to drive it. This one was bad enough to give wisps of black smoke when driving. Bad enough to eat a piston. These Dmax engines are VERY tough, but driving with bad injectors is certain to lead a piston(s)to an early grave.

8 LB7 injectors with 8 new hard lines and all of the proper TLC will set you back around $4000-4500 here and dealers have been quoting well north of $5k WITHOUT the new lines. Invest the savings in lift pump and filtration upgrades to help prolong your injector life.

[Mark Rinker]

The possibility of a "harness issue" is NO MORE COMMON than any connector/harness issue in ANY other vehicle, or any other vehicle system. The harness issue Mark suggested it UNIQUE to the 2004.5-2005 LLY engines, when the #2 and/or #7 injector harness fails. This is a known issue and there is a TSB to address it, and it is not/can not be the same for an LB7. If you have a harness issue with your LB7, it will be rare and in no way related to any commonly known issue. This does happen, but only because it happens in all vehicles from time to time.

Smoking at idle with a miss is most likely injector(s). Check your oil level often. An overfull crankcase will also cause rough running (perceived as a miss), due to the elevated crankcase pressure and imbalance. There are other possible causes, but they are common to all vehicles on the road (fuel quality, climate/temperature, filters, emission system, etc.).

Sorry if I muddied the waters here. Agreed that a harness related issue is uncommon for your model year.

However, I do stand by getting a diagnosis done at Miller Chevrolet, which is close to your location, and a reputable dealer. As for diagnosis costs, that is an important discussion to have up front, with your Service Advisor. Ask for Wade Hanson (recently new hire - previous GM experience from another dealership - longtime friend and trusted mechanic for MRE) and tell him Mark Rinker referred you. His brother Terry is a tech in the same shop. I trust them with any of my stuff, and to be honest in their billing.

If it does turn out to be bad injectors - by all means replace all 8 and I would not be shy in asking GM to review your case since your miles are so low. You have received about half of the miles one would expect before looking at $5K of injector replacement. They have latitude in covering all or part of your repair. ASK THE HARD QUESTIONS - UP FRONT!

As for injector lines - agreed they should be replaced, especially in a salt/sand state like Minnsota. I had two sets of LB7s injectors replaced (2001, 2002) at the now defunct Elk River Chevrolet dealership, they quoted over $1000 part cost for 8 lines. Was able to source OEM parts on the internet for a fraction of the cost, and supplied the lines myself. It took a bit of diplomacy, but they could hardly argue the outrageous difference in cost.

Best of luck - stay in touch here on TDP as your diagnosis progresses. DO NOT drive the truck if oil dillution or a fuel knock starts.

[deerhunter7]

I am going to drop it off tonight and will discuss options with them. If it is injectors I may do them myself or maybe take a trip to Kennedy Diesel ..Thanks again.. Dropped off . $ 98.00 to check it out ... Will find out Thursday ..

[Kennedy]

I am going to drop it off tonight and will discuss options with them. If it is injectors I may do them myself or maybe take a trip to Kennedy Diesel ..Thanks again.. Dropped off . $ 98.00 to check it out ... Will find out Thursday ..


I guess I gotta start charging more for diagnostics. Hook the Tech 2 up and 15 minutes or less you'll have a pretty good idea. That and the plume of smoke at idle when warm is a pretty dead giveaway. I'd be curious to hear which cylinder it is that is worst if they can narrow it down that far.

We keep the stuff on hand for the most part. Occasionally we get a delay in shipping. Of course I now have a set of 7 lines because I broke down and sold a single to the local guy, but I should have another set or two on hand.

[deerhunter7]

Dealer called and said #7 injector is bad . Rest were in specs. Quote $4900 to change all 8 or $1400 to change #7 . Also suggeted to flush clean the other ones. I think I am going to try and run some heavy injector cleaner for a couple tanks and see if that makes a diffrence.Problem seems to be carbon build up on tips ? Maybe thats whats wrong with #7 ,loading up at idle.. When I picked up my truck got yo meet and talk to the mechanic . He explained whats goimg on that the ball is not seating ,agreed that I should try some heavy cleaning and if that did not work then he suggested changing out that bank of injectors . He also told me I have a bad thermostat that they were opening at 170 which would hurt my mileage . So thats my project tonight . So to me it was worth the $100 to know whats going on .

[Kennedy]

The thermostat project would coincide nicely with the injector job as coolant is drained for this as well.

Carbon on the tips is more of a symptom of bad injectors/fuel/combustion.

The ball seat is up in the body of the injector. If one is bad, the others are close and I doubt any additive will help. I've run 1/2 bottle of Total Power in one w/o results.

[mattb5150]

If you are short on the cash I think the techs suggestion to do the one bank is where to start, just changing one injector blows a lot of labor if the others on that bank go out soon. This is what I did, of course a few months later I had a bad one on the opposite bank and had to do those as well. Make sure they change out the hard lines, like Kennedy suggests, while they are in there.

[jjcsnlynn]

Not to hijack this thread, and bear in mind I'm new to the Duramax scene, but why do the injectors cost $5000? I can understand the labor with them being under the valve covers, and fluid changes, etc, but I can buy injectors for my Passat TDI for a couple hundred each?

How can I check when the injectors were last changed in my 2500HD? It has 173K miles on it and I didn't get any history with it.

Jon

[deerhunter7]

The cost of injectors is partly the metal and engineeing and what the market will bear. Prices have come down from where they first started. After the thermostat change out [thats 2 of them} And 1 tank burned up I did get 16.7 miles a gallon running the he!! out of it . Idle is smooth as silk but still have smoke at idle .Did smell and white paper test to oil and it is still just oil. Also coolant stayed full after thermostat change. Now runs 15 to 20 degrees hotter.Running another tank with injector cleaner as nothing to lose . |My 1 thought is been running cool has loaded up with carbon or dirty seat . Also no codes on computer..|Of course if this all fails then back to plan A. Change injectors...

[DmaxMaverick]

Stay optimistic and stick by your guns!

However, fouled injectors (external nozzle sooting) on these is a symptom, not a cause. Running too cool effects combustion, but does not effect the internal function of the injectors. Internal leaks are almost always caused by "ball seat erosion", which is a degradation of the metal sealing surfaces inside the injector. However unlikely, you could have a particulate contamination of the seat, which may be helped by an cleaning additive. If you are serious about trying this, I suggest using Sea-Foam. It seams to work the best for this, under just about all conditions. Good luck, and cross your fingers (it helps as much as anything).

[deerhunter7]

Finished changing all 8 injectors last night . All tips had carbon around them , wasted money on cleaners . Runs good and smoke at idle seems to be gone .No leaks and looks just like it came out of factory . Now just have to send cores back to Kennedy ..

[Mark Rinker]

Thanks for keeping us up to date. Better luck with the next 100-200K miles!!!