LB7: NEED HELP, LB7 white smoke+ no codes+backfiring randomly

dirtymax36

dirtymax36

2nd place is last
Apr 11, 2013
367
2
18
Cruising home one day in my 01 lb7 that I put new s+s injectors and fpr in back in september. I went to plug my CTS monitor in and when I did I got a big pop backfire along with white smoke and injector knock. Went into limp mode also. I trailered it home and checked all top engine harness connections along with codes and all I get is a u1800. Sometimes it won't have any codes when you turn the key. I've tried a different ecm, and FICM. I also checked the harmonic balancer for any broken crank and or/sheared pins. Feel free to contact me on here and I can send someone a video of it running to help. Any help here? I'm at a loss. Thanks in advance!

FYI the truck ran great and was drove almost daily since purchasing in august. It's all stock except for a lift pump exhaust and simple dsp5.
 
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aashton1206

Member
Sep 3, 2015
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What brand injectors did your use?

Is there fuel in the valley?

Is there fuel in the crank case?

The white smoke is unburnt fuel in your cylinders, what does your coolant look like?
It sounds like a structural failure somewhere and you lost compression so fuel is going unburnt. I would get a compression test on the cylinders.


2004 Silverado Cali lb7, Airdog ll 165, fresh sticks at 325k, custom tuning on v2 for daily driver, 33x12.5 nitro at on 20 inch American steal wheels, modded factory air box, Profab Intake Horn, Batmo Wheel, Turbo port and polish, Full EGR Removed w/ fed belt, 3.5 inch MBRP Downpipe, Full five inch MBRP Exhaust w/ 6 inch tip, 10mm lbz cp3 pump, Dual Yellow Top Optimas, High Output Alternator, Cognito Pittman and idler w/ support kit, Cognito Contol arms, Drilled and Slotted Rotors on all four Corners, FEd Y Bridge.
 
dirtymax36

dirtymax36

2nd place is last
Apr 11, 2013
367
2
18
I used s+s. No fuel leaks or anything internally or externally. No coolant issues such as a blown head gasket or cups leaking. It was running great all the way to work and back and close to home is when it did it. In my video it'll run without injector knock for a few seconds then it'll begin knocking along with surging. Acts like it spun the cam key on something. No timing sensor codes either
 
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tsd_billy

Member
Apr 5, 2016
457
0
16
oklahoma city
dirtymax36 said:
I used s+s. No fuel leaks or anything internally or externally. No coolant issues such as a blown head gasket or cups leaking. It was running great all the way to work and back and close to home is when it did it. In my video it'll run without injector knock for a few seconds then it'll begin knocking along with surging. Acts like it spun the cam key on something. No timing sensor codes either
Click to expand...


Flash it back to stock and see what happens. Cant hurt to try that


Sent from my iPhone using Tapatalk
 
dirtymax36

dirtymax36

2nd place is last
Apr 11, 2013
367
2
18
Put a stock ecm I have licensed here to my v2 on it and still has the same symptoms. I tried a spare ficm here and didn't cure the issue unfortunately
 
dirtymax36

dirtymax36

2nd place is last
Apr 11, 2013
367
2
18
Yes sir on each harness bale connector. I took the injector plugs off and dielectric greased all plugs
 
dirtymax36

dirtymax36

2nd place is last
Apr 11, 2013
367
2
18
Grounds checked and tried an ficm off another running truck here and no such luck. Any other ideas before i pull the front clip off to check the cam dowel pin?
 
dirtymax36

dirtymax36

2nd place is last
Apr 11, 2013
367
2
18
Just polished up all the grounds and checked fumes, the ficm is labeled ecm2 correct ? It's an 01.

And miles don't matter, it has 220k.
 
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aashton1206

Member
Sep 3, 2015
172
0
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Listen to the block with a stethoscope


2004 Silverado Cali lb7, Airdog ll 165, fresh sticks at 325k, custom tuning on v2 for daily driver, 33x12.5 nitro at on 20 inch American steal wheels, modded factory air box, Profab Intake Horn, Batmo Wheel, Turbo port and polish, Full EGR Removed w/ fed belt, 3.5 inch MBRP Downpipe, Full five inch MBRP Exhaust w/ 6 inch tip, 10mm lbz cp3 pump, Dual Yellow Top Optimas, High Output Alternator, Cognito Pittman and idler w/ support kit, Cognito Contol arms, Drilled and Slotted Rotors on all four Corners, FEd Y Bridge.
 
Chevy1925

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,685
5,840
113
Phoenix Az
dirtymax36 said:
Just polished up all the grounds and checked fumes, the ficm is labeled ecm2 correct ? It's an 01.

And miles don't matter, it has 220k.
Click to expand...

check ALL your fuses. since you say you plugged the CTS in and thats when it started, i would be looking to see if plugging that in blew some fuses. the top of each fuse will have little tiny metal ends that you can use a test light or multimeter on to see if power is on both sides. if there isnt, thats a blown fuse. this way you are not pulling every single fuse out to inspect.
 
07keo02

07keo02

New member
Oct 5, 2011
399
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0
Phoenix, AZ
You have a v2 right, if so have you used efi live software to cut out one cylinder at a time. And, did I read correctly that this happened the moment you plugged in the cts?
 
dirtymax36

dirtymax36

2nd place is last
Apr 11, 2013
367
2
18
Checked fuses and they're all good. I also tried trying to run it without the radio fuse in, sometimes that makes a difference while efi flashing. No luck
 
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