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2016 Sierra 5.3L L83 new injectors now runs rich.

JAI3

By JAI3
in Engines & Drivetrain

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JAI3 New Member

JAI3

Posted
Posted

 I had a evap sol go bad a couple weeks ago. . I replaced it. 
While watching live data at the time I saw I had some cylinder 1 misfires. No MIL but on live data I could see ~50 at startup and about 70 more after an hour a drive all on cyl 1. 

I also noticed that the LTFT were -5% to -15% always. 
And that bank 2 is always -3% richer than bank 1. Even across all driving modes, city, highway, etc it’s always 3% richer than bank 1.

So I start with the misfire. Swapped coil, plug, and plug wires from 1 to 3. No follow. I got an Injector reseal kit, pulled the D/s injector rail, swapped #1 and #3 injectors, resealed them, reinstalled and retested. 

The misfire followed to 3. So I ordered and replaced all 8 injectors, spark plugs, and plug wires. Also replaced the 1 time use fuel pipes under the intake manifold. 

Injectors that were in the truck since new were 
Part # 12668390. 
I replaced them with # 12742701
Got from RockAuto. Pretty certain they’re genuine and the correct ones. I called a friend at a parts store who told me “the 12742701 were the correct superseded part # for the originals I was replacing”.

So started truck after replacing all that and it’s running -15 - -30 LTFTs. I reset the fuel trims with GDS2 and drove it for a 60 miles trip each way. There have been no changes in the LTFTs. 

I checked if the HPFP was leaking into the crankcase. I removed the pvc and watched the trims. No difference. 
I checked the alcohol content and it was at 10% 

I’m out of ideas here. Truck seems to run great. Just always rich on the fuel trims. 

Anyone with any help or ideas would be greatly appreciated. 

I ran an injector balance test just for the heck of it and it came back this. I’m confused. 
I have gds2 and some other diag tools if anyone knows of anything I should test next.

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      2016 Sierra 5.3L L83 new injectors now runs rich.

      By JAI3 · Posted

      I had a evap sol go bad a couple weeks ago. . I replaced it.  While watching live data at the time I saw I had some cylinder 1 misfires. No MIL but on live data I could see ~50 at startup and about 70 more after an hour a drive all on cyl 1.  I also noticed that the LTFT were -5% to -15% always.  And that bank 2 is always -3% richer than bank 1. Even across all driving modes, city, highway, etc it’s always 3% richer than bank 1. So I start with the misfire. Swapped coil, plug, and plug wires from 1 to 3. No follow. I got an Injector reseal kit, pulled the D/s injector rail, swapped #1 and #3 injectors, resealed them, reinstalled and retested.  The misfire followed to 3. So I ordered and replaced all 8 injectors, spark plugs, and plug wires. Also replaced the 1 time use fuel pipes under the intake manifold.  Injectors that were in the truck since new were  Part # 12668390.  I replaced them with # 12742701 Got from RockAuto. Pretty certain they’re genuine and the correct ones. I called a friend at a parts store who told me “the 12742701 were the correct superseded part # for the originals I was replacing”. So started truck after replacing all that and it’s running -15 - -30 LTFTs. I reset the fuel trims with GDS2 and drove it for a 60 miles trip each way. There have been no changes in the LTFTs.  I checked if the HPFP was leaking into the crankcase. I removed the pvc and watched the trims. No difference.  I checked the alcohol content and it was at 10%  I’m out of ideas here. Truck seems to run great. Just always rich on the fuel trims.  Anyone with any help or ideas would be greatly appreciated.  I ran an injector balance test just for the heck of it and it came back this. I’m confused.  I have gds2 and some other diag tools if anyone knows of anything I should test next.
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