Yeah. It gets worse now that I've test run. Lumpy idle, can't rev for more than like 1 minute, won't do more than about 20 mph. Low rail pressure. My two suspects are that crap somehow got into the fuel pressure regulator suddenly, or I now have a bad replacement #4 injector that is returning fuel to the tank at too-high a rate.
I pulled codes and got P0087, low fuel rail pressure, and P1232, which is Injector 4 not behaving as commanded. I need to check the #4 wiring harness to see if anything is chafed or broken since I disturbed everything. After that and trying again, see if there's still a P1232 code. If/when that's resolved, I'll probably make a blocking plug out of an old injector line and the removed "old" #4 injector and see if the fuel rail can build pressure. After that, if still not building rail pressure, I'll chase the fuel pressure regulator.
2001 Duramax LB7 Knocking
Re: 2001 Duramax LB7 Knocking
Installation error/cleanliness was "definitely" the cause of issues yesterday. It's possible that 1/9 reman injectors was faulty, I guess. Hopefully this saga will end someday...
Re: 2001 Duramax LB7 Knocking
Direct injection, particularly diesel common rail, seems to nearly require a clean room to service it. Imagine dumping (even somewhat filtered) waste oil into it. It's a far cry from old mechanical stuff.
Re: 2001 Duramax LB7 Knocking
I know. I thought I was careful.
Re: 2001 Duramax LB7 Knocking
I'm really thinking I should "limit" initial steps here to chasing the #4 injector since that's the "only" thing I changed now. I could even swap in the removed #4 injector since I got the hunk out of the inlet and see if it re-improves
Re: 2001 Duramax LB7 Knocking
Generically I would say go slow and be very meticulous. Your favorite things!
Re: 2001 Duramax LB7 Knocking
It was making me crazy thinking I might've left the wires off or loose on the #4 injector somehow, especially with inj 4 error code. I pulled the upper valve cover to check - it was all fine and correct. I also wanted to look for evidence of diesel leaking into the valve area somehow not permitting full rail pressure. No evidence of that either. Since I had the upper valve cover and all the injector feed lines off anyhow, I decided the worse-calendar time-but-less-labor/effort path was to take both #4 injectors back to the injection shop to have them performance tested. If I come back with a "known" good #4 injector than I will look into more potential issues. I think I can at least drop them off before my class starts at 9:30 tomorrow.
Re: 2001 Duramax LB7 Knocking
Went to Metro Fuel Injection this morning. They tested the "replacement" #4 injector - I'm glad I was there to watch the test and understand what was going on, because I at least now have a hypothesis for the symptoms. When setting up for the test, the technician noticed very, very minor weeping out of the injector inlet and had to retighten the inlet fitting two times as the pressure came up to the final 150 MPa (~23k psi) test. This got me thinking that I have used only the stock 30 ft-lb torque applied for all of my line fittings. Test came out OK - looks like 10 or 15% "higher" flow for the pre-injection volume, but all other values were in spec.
The manager encouraged me to talk to their mechanic about the problem to see if he had any advice. When I went over it with him and mentioned the line sealing concern, he thought that was a likely cause. He does not use a torque wrench on any of the line fittings on the injectors or the fuel manifolds, and thinks he likely goes much higher than 30 ft-lbs. The replacement injectors are remanufactured injectors, which means the inlet fitting is used. There is evidence of earlier corrosion that has been cleaned off in non-sealing areas, and the line fitting seat doesn't look 100% immaculate, but it doesn't look bad either. Probably 20-30% higher torque will be warranted and hopefully make me all set.
The manager encouraged me to talk to their mechanic about the problem to see if he had any advice. When I went over it with him and mentioned the line sealing concern, he thought that was a likely cause. He does not use a torque wrench on any of the line fittings on the injectors or the fuel manifolds, and thinks he likely goes much higher than 30 ft-lbs. The replacement injectors are remanufactured injectors, which means the inlet fitting is used. There is evidence of earlier corrosion that has been cleaned off in non-sealing areas, and the line fitting seat doesn't look 100% immaculate, but it doesn't look bad either. Probably 20-30% higher torque will be warranted and hopefully make me all set.
Re: 2001 Duramax LB7 Knocking
Looks like line leaks have plagued at least a few others:
https://www.dieselplace.com/threads/inj ... ak.447899/
https://www.dieselplace.com/threads/inj ... ak.447899/
Re: 2001 Duramax LB7 Knocking
It's just occurred to me that if this is the problem you were having then you probably need to change your oil.