I recently completed an LS7 Swap in my 1973 Corvette with a TKO500 Manual Transmission. Everything has been running smoothly until after I had it tuned, which I am trying to figure out if the issue is related.



From cold start, engine will run great. It will run and perform the way it should, I can let the car warm up, give it some throttle, it runs nice with no issues. Then after about 20min of running, the engine will go in and out of a low power condition. If I give the car throttle while it's in this condition, it will just hold rpms and make a whistling noise. If I let go of the throttle, the car will run very rough and die. I can then start the car right back up, but then will consistently have it go in and out of this low power condition until I park the car and let it cool down.

When I run my engine code scanner, this are the codes I'm getting:

- P0223 - Throttle/Pedal Position Sensor/Switch "B" Circuit High
- P2122 - Throttle/Pedal Position Sensor/Switch "B" Circuit Low
- P0122 - Throttle/Pedal Position Sensor/Switch "B" Circuit Low
- P0113 - Intake Air Temperature Sensor 1 Circuit High Bank 1
- P0202 Status: CURRENT - Cylinder 2 Injector "A" Circuit
- P0206 Status: CURRENT - Cylinder 2 Injector "A" Circuit
- P0506 Status: CURRENT/HISTORY/MIL - Idle Control System PRM - Lower than Expected

So far I have replaced the Throttle Position Sensor/Gas Pedal, the Throttle Body, and traced back through all the wiring in-between.

Any ideas of what else could be causing the problem?

 

When you start seeing multiple devices with current or voltage out of range it hints of a general issue of harness integrity. Maybe start with grounds and follow your nose from there.

 

Of all things, it turned out to be a burned O2 sensor wire! I went back through the wiring and heat wrapped more of the harness, as well as moved all of my +12v connections for the ECU and electrical fans to a junction block. No codes now and runs great.

 

At least you did it. Thanks for letting “US” know

 

I always love reading a success story like this! Thank you for coming back into the thread and letting us know how you fixed the problem.