Major LB7 problems -- need help

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Citidiot90

Person
Apr 22, 2020
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Canada
blk smoke lb7 said:
That's quite the buffet of codes there not sure what's going on. That center section of the turbo needs to be balanced was that done?
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Yes I purchased the entire assembly with new turbine, shaft, compressor wheel and bearing housing pre assembled and balanced with the gaskets and banjo washers. Just reused housings and v band. Was very careful putting together as to not make contact. Cartridge came oiled but I also followed the priming procedure as directed by the manufacturer.

Dropping the truck off to a local diesel shop to have it diagnosed. Hopefully he can find something. Will post results. Hopefully I haven't wasted parts on a blown motor
 
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KyleC4

Tech
Dec 30, 2016
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Bay Area
From that data and only pulling 22lbs/min of air at 20k psi rail is not enough. Shows as well with only making 6psi over baro. Maybe there is nothing wrong with the cartridge you put it but what about the valve on the exhaust housing. Is The wastegate link possibly misadjusted and holding the wastegate partially open? Well post back what they find and good luck
 
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Citidiot90

Person
Apr 22, 2020
24
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Canada
KyleC4 said:
From that data and only pulling 22lbs/min of air at 20k psi rail is not enough. Shows as well with only making 6psi over baro. Maybe there is nothing wrong with the cartridge you put it but what about the valve on the exhaust housing. Is The wastegate link possibly misadjusted and holding the wastegate partially open? Well post back what they find and good luck
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Thank you so much for your input. I checked the valve when it was off and aside from some slight pitting the valve seemed to set nicely with no cracks or obstructions. Not sure how to adjust the actuator but I did have to out air pressure into the actuator just to get the link into the hole. Lots of spring pressure holding it closed (it was about 1/2 inch too short at rest) this all leads me to suspect some other leak of drive pressure before turbo. No smoke from under hood visually but quite loud idle. If it turns out to somehow be the turbo housing itself I have a spare as well as spare actuator although they are from a mystery turbo I got for next to nothing and was full of water and corrosion on compressor side. Both actuators tested moved at the same air pressure. I suppose though what you've indicated to me is that it certainly wouldn't be a boost leak causing this since the brand new MAF isn't seeing the flow rate? Also, I read somewhere that after some time a faulty MAF or reading could force into open loop operation? Is there some type of relearn procedure or should the ecm figure out that it's got new parts?
 
Bdsankey

Bdsankey

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Feb 1, 2018
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Have you tried a different MAF? Is the MAF clean? Is the air filter clean/no obstruction? Pulling only 22lb/min of air is low for the truck to demand 20k rail as noted in another member's post.


Also can you elaborate on the "no smoke from under hood but quite loud at idle"? Loud as in engine noise? Exhaust noise?
 
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Citidiot90

Person
Apr 22, 2020
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Canada
The old MAF was dirty and one of the elements looked burnt. Swapped it out with a brand new MAF from dorman. Was checking visually for smoke while a buddy did a brakestand in the driveway. Although with the wind we've had here it's hard to do any diagnosing like that. When I stick my head in the wheel wells it is a fairly loud tick. Can't remember what it sounded like before all this tbh. Air filter is also brand new(stock paper element). Fuel filter brand new. Fresh oil and filter.
 
Bdsankey

Bdsankey

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Citidiot90 said:
The old MAF was dirty and one of the elements looked burnt. Swapped it out with a brand new MAF from dorman. Was checking visually for smoke while a buddy did a brakestand in the driveway. Although with the wind we've had here it's hard to do any diagnosing like that. When I stick my head in the wheel wells it is a fairly loud tick. Can't remember what it sounded like before all this tbh. Air filter is also brand new(stock paper element). Fuel filter brand new. Fresh oil and filter.
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Put a known good GM MAF in. There have been too many issues documented with parts store branded MAFs in terms of accuracy/reliability.
 
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Citidiot90

Person
Apr 22, 2020
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Canada
I'll try to track down a gm sensor. Still scratching my head here about the chain of events that happened. I'm sure that the hole in my intercooler must have caused other problems. Is it possible that I have lost compression in the motor from driving with under boost condition ? I haven't checked as I don't have the tool. I just feel like if that was the case I would have a hard start/rough idle/smoke at idle. But that's not the case. Starts within first second of cranking even at negative temperatures. No haze at all. No surging. Smells clean. I'll be honest I let my oil go past it's time this winter and fuel filter too. Probably by a couple thousand km. Although after rebuilding the turbo it seems like my old turbo might have been perfectly fine. Does the boost sensor play a role in fueling or is it just there for diagnostics? I looked on Mitchell and it doesn't seem to have much information for the diesel motor. My analog boost guage reads slightly higher than what the sensor is telling me. About 10 psi when the sensor reads 6
 
DAVe3283

DAVe3283

Heavy & Slow
Sep 3, 2009
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Boise, ID, USA
I can confirm that parts stores MAF sensors are junk. Had my stock one fail (melted due to high engine bay temps). The parts store one was just off its nut, would read OK until I got some airflow, then jump up and down randomly. Definitely get an OEM sensor.

Have you checked for crankcase pressure / excessive blowby? The classic trick is to let the truck idle and flip the oil fill cap upside down on the filler. It should just sit there, not jump around.
 
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KyleC4

Tech
Dec 30, 2016
470
48
28
Bay Area
So did the local diesel shop not come up with anything? Only thing I can think of here is going back to beginning of failure and look over everything again. Damaged intercooler.... look at new intercooler and piping, couplers, for any damage, leaks, restrictions. Then look further possibly into intake bridge and manifolds.
 
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Citidiot90

Person
Apr 22, 2020
24
0
0
Canada
So the mechanic called me yesterday and told me that he had suspected injectors from the jump( it's true, and I didn't want to believe) so my number 3 is doing the most damage. When turned off the smoke goes away and power starts to come back. Im planning on swapping out the one injector and see how it drives. I know that's ridiculous but I can't afford to do anymore right now. I don't know much about balance rates but in hindsight, cylinder 3 did look kind of off to me.
 
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N2BRK

Well-known member
Dec 31, 2009
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I'd run a compression check on all cyls. Hopefully that injector didn't hang open and cause a problem. *disclaimer... I'm just a hobbyist, so if one of these pro mechanics says I'm wasting your time, listen to them instead. LOL
 
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Citidiot90

Person
Apr 22, 2020
24
0
0
Canada
N2BRK said:
I'd run a compression check on all cyls. Hopefully that injector didn't hang open and cause a problem. *disclaimer... I'm just a hobbyist, so if one of these pro mechanics says I'm wasting your time, listen to them instead. LOL
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Lol Its not bad advice. I don't have a compression tester unfortunately. Do you check compression through injector holes or glow plugs holes? I've heard of both methods depending on the tool. The tech who has my truck also told me that with faulty injectors I could lose compression through the injector itself. Waiting on a call back to see what he thinks I should do. Hes quite convinced it's more than one Injector hanging open. Said he heard the fuel knock as soon as I pulled up. I know you can't compress a liquid so I assume something would have to give up and get out of the way. Just hoping I can decipher that without pulling my head's or worse.
 
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