LS2 Swapped humvee help TOTALLY STUMPED

Punisher

Punisher

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I have a restomodded humvee that I put an ls2 in and it was running great for a few months and now I cannot figure out what is the issue here. The passenger side plugs are totally black after only a few hours. Driver side looks perfect. I have changed plugs, wires, coil packs, O2 sensors, cleaned the maf sensor, new map sensor etc. It will run fine for 10 mins and then throw a code that it's too rich on that bank. Any ideas? There is only so much crap on these engines for god sakes 

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If were me I would start looking at the fuel rails and/or exhaust.  

I can't believe its electronic.. 

 
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Bobalos said:
If were me I would start looking at the fuel rails and/or exhaust.  

I can't believe its electronic.. 
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Not sure what I would look at in the fuel rails? Also exhaust other than O2 sensors. 

 
That looks like the truck intake.  TBSS or SSR? What ECU, E67?  Are you running HPT or something similar?

 
It should have O2s on each bank.  You should be able to see the O2 value, and cylinder balance, on your scan tool.

 
I would check to make sure the O2 Sensor wires are not switched, 

if the banks are backwards it will run rich,  

Try swaping them and see what happens 

 
J Alper said:
I would check to make sure the O2 Sensor wires are not switched, 

if the banks are backwards it will run rich,  

Try swaping them and see what happens 
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did that today, thought that was gonna be the issue but no go.,.,.

 
I have had so many issues with Factory ECM's i pretty much done with them, 

Always something with a sensor that is the same part number that does not work the same, or a ECM not working correct, 

I would have someone read it with a Snapon Scanner, and if it is a ECM,  I would Thing about a Holley system,  It uses wideband and for what you are doing, I think you would really like it, 

 
Intake leak? What maf are you running? Stock or aftermarket? Tried swapping out o2 sensor on just the right bank?

 
Fuse for the passenger bank coils or injectors?

Ground come loose?

Gotta be something simple since it was running fine.

 
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If all of that bank is rich, gotta be something common. Either the coil pack or injectors common ground or hot.

Oil smell like gas?

 
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I don’t know much about those motors but I seem to remember a friend having a similar issue on an LT motor. I think it ended up being the fuel pressure regulator leaking internally and it was sucking gas into the intake. 
Otherwise as suggested it’s probably an issue with just that bank. Injector wiring, o2 sensor. 🤷🏻‍♂️

 
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I'd check the ECU ground/ignition for correct voltage/resistance as well as the common engine ground.  

 
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