I have a 2004 LS6 that I dropped into my 1968 Corvette. I finally got it running by loading a stock tune into HP Tuners but when she warms up she starts to run very rough. It sounds like she wants to stall but I can give it some gas and she will stay running. I ran a code reader and I get two codes:

P0172 Fuel Trim System Rich (Bank 1)
P0174 Fuel Trim System Lean (Bank 2)

 

Could be O2 Sensors plugged into the wrong sides.

 

I dont think so. The cable are only long enough to reach the proper sides due to the way this harness is set up

 

That doesn't mean anything, if it's not the factory Harness it could be built wrong. I've fixed several big name professionally built Harnesses over the years.

I would check it.

 

how do I check it? Do I unplug one of the O2 harnesses and see which one comes up with an error?

 

You get the pinout diagrams, get a multimeter and make sure the O2 Connector Wires are where they should be at the PCM Connectors.

I take it you don't know much about wiring or any of that.

 

I know how to check pins its just my PCM is not in a great location for that.

 

That's the way it goes sometimes. The codes you have are what I've seen in the past as the Sensors on the wrong sides, if the Harness checks out then it's something else, but first thing I would check is making sure they are on the correct side.

 

yeah, Im going to dig into it. I always do I just mumble and grumble for a while

 

Or simply swap the O2 connectors side to side if you have enough length to do it. It would be an odd situation or a poorly constructed harness if you don't have enough length. Go to the junk yard and find the same style of connectors, wire colors, etc. to add length if you need it. It might require some soldering and shrink insulation repairs.

Your symptoms are exactly what my engine problem was a few months ago when user "Gametech" around here suggested swapping the O2 sensor connectors on my Pontiac Catalina. Fixed it!! I promptly color coded my O2 sensor connectors with a dab of Testor's model car paint so that I will never make that mistake again.

Rick

 

Glad the stock tune got you running!
You could just do like you said and unplug one side and see which one throws a different code, driver side is bank 1 passenger side is bank 2 of course.

Also you said you believe the engine has a large cam, so it would most certainly not run very well with the stock tune file.
Did you put the factory injectors back in or are you still running those amazon ones?

 

I bought a good set of Bosch injectors.

 

I forgot about the Cam part, so if you loaded a stock tune it won't run without help if there's an aftermarket Cam in it.

Has that been verified?

 

So after talking to the guy who built my harness and chasing wires he had the two O2 sensor wires backwards. You all were right. I just got done swapping them so I’ll test it here in a little bit.

 

Yup, fixed stuff like that before why I called it.

 

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