One bad injector???

[chrisinkanata]

All 8 of my injectors were replaced by GM 2 yrs, 25,000 miles ago. Playing around with my Autoenginuty scanner a few days ago and stumbled across what appears to be a potential injector issue in that one cylinder's balance rate is consistently in the 8 - 9 range. All others are in the .5 to 1.5 range. No drivability issues or other symptoms. Kennedy secondary filtration and consistent diesel additive since the last injector change.

Any thought?

Chris

[Kennedy]

Is this the first time you looked at the balance rates? Did the dealer replace all 8 supply lines when they did the injectors?


Before losing any sleep over this, I would be inclined to have this checked with a Tech 2 scan tool for verification. Check hot in Park. I'll also add that too many people fret about balance rates and put too much stock in the results. Balance rates are just a generalization and actually a bit more "cylinder contribution" related. In other words, if say you had a bent rod, burnt valve, cracked/holed piston, that particular cylinder would read high positive as the ECM tried to deliver more fuel to equalize the contribution of said cylinder.

I've had pretty decent luck dosing heavy with FPPF Total Power when an injector gets out of line, but it's a crap shoot as to whether it lasts or not.


Semi related story:

I had a guy come in with a bad injector that smoked black and knocked hard even under light driving. I told him I felt the LB7 injectors were an all or nothing proposition, but he could only afford one and not at the moment. He left with the truck after I had warned him it was not long for this earth the way it was running. He came back and picked up his one injector, took it to his mechanic and brought the truck back. No more knock , but it still felt wrong. I felt a miss in it. Balance rate on the suspect cylinder was 15. I brought the RPM's up to about 2000 and watched the plume cross the drive in the wind. The plume was crankcase vapor. Piston shot.

[More Power]

25K is way too few miles for a $4500 set of LB7 injectors (parts & labor).

Unless the truck has been abused in some way since the last injector service I'd visit the dealership or mechanic who did the work, and ask for some sort of consideration for the repair cost.

GM has to know that these sorts of stories must have an effect on new and used truck sales - if the last set was a dealer service. I wonder whether a GM dealership would replace all 8 25K injectors for a single out-of-spec injector?

Jim

[chrisinkanata]

Thanks guys. Over the next 6 weeks, we have a vacation planned heading down to Myrtle Beach. When we get back, I'll get it back into the dealer. Before I leave though, I will speak to the service advisor I know there and give him the heads up in the event something happens while I'm down there. Maybe it'll help, maybe not, whatever. In terms of the supply lines, no they were not replaced. This is the first time I've checked the balance rates in a year. Based on what GM says, I think I'll just drive it until I get some other symptoms like the white smoke at idle two years ago. If that happens, I'll just do the one injector myself and trade it in. 300,000km relatively issue free so it doesn't owe me much. Really appreciate your input.

Chris