[jeff.james66]

Replaced Petal position sensor, cleared codes, error came right back. Instantly puts car into limp mode, reduced power, no traction control, no power steering. Basically running like crap. This is new motor. LSX 440, Wiseco Pistons, Eagle Rods, Comp Cam & Lifters the works. Any Ideas?

 

[racingvette]

Cannot help if you do not post what all the DTCs are

Drive by wire is designed by GM to assure no faults for safety and the controllers are doing cross checks tests to
be sure no fault would cause car to crash and why PCM will go into limp mode and limit the MPH

The gas pedal sensors have to match what the DBW controller was designed to so be sure if you replaced
the GP that it is for that model year
Assure main ground from frame to engine is good

Also on the throttlebody is a TPS sensor
It has to report the same angle of butterfly as the angle reported for the GP
Really need a OBD-II scanner and see if the TB and GP values equal
Also assure the TPS is sync'd with the PCM and might need a TPS/PCM relearn process

 

[jeff.james66]

Cannot help if you do not post what all the DTCs are

Drive by wire is designed by GM to assure no faults for safety and the controllers are doing cross checks tests to
be sure no fault would cause car to crash and why PCM will go into limp mode and limit the MPH

The gas pedal sensors have to match what the DBW controller was designed to so be sure if you replaced
the GP that it is for that model year
Assure main ground from frame to engine is good

Also on the throttlebody is a TPS sensor
It has to report the same angle of butterfly as the angle reported for the GP
Really need a OBD-II scanner and see if the TB and GP values equal
Also assure the TPS is sync'd with the PCM and might need a TPS/PCM relearn process

Hello,

Thank you so much for your reply. You have got to be the first person I've spoken with that really knows what they are talking about. I do not own an ODB-ll scanner the codes I can get are from my Diablo tuner. It does a good job at displaying codes but that's it. No values as far as the sensors go. So, today I went out and cleared the codes and started the car. It Idles ok and let me rev to about 3k ok. As soon as I revved past 3k it went to limp- check engine, reduced power, ABS, etc. This time there were more codes.

ECM0122: Throttle/Pedal Position Sensor /Switch A Circuit Low
ECM0222: Throttle/Pedal Position Sensor /Switch B Circuit Low
ECM1516: Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance
ECM2101: Throttle Actuator Control Motor Circuit Range/Performance
ECM2135: Throttle/Pedal Position Sensor /Switch A/B Voltage Correlation

Previously when I touched the TB connection it would make a funny noise like a vacuum motor or something that sounded like it was coming from front of car, then it would instantly go to limp. I guess that's what its called where it displays all the check lights and reduced power, feels like its running on 4 cylinders. I did change the Throttle/Pedal Switch, actually replaced under warranty by Orileys Auto Parts. The last one was replaced back in June. It resolved the issue at that time till now. I couldn't really tell any physical difference in that one and the new one.
I also have a Nick Williams TB if that makes any difference. I feel like it may have had a bad connection because when I would touch the wire harness on that side it would do the limp thing. So I checked the plug and used a small screwdriver from the back of the plug I gently pushed each terminal to make sure the pins were making good contact. After that is when I was able to rev to 3k but once revved higher that's when I got the 5 codes listed. So your information about the TB Butterfly makes a lot of sense. I may need to return the pedal and get a genuine OE part.

Thanks again for your help,

Jeff

 

[racingvette]

All your DTCs are related to the drive by wire.
Not sure when you changed the gas pedal for the problem at that time
If so then it is not the pedal sensors but again being all this works from 0 to 5 volts and at the same time
5 volts to zero and then the TAC (DBW ) controller in the PCM is doing a compare of A and B sensors and
not seeing a match
3rd party pedal though may be adding more to the problem as not matching exactly the specs GM gas pedal sensors are

You could for testing is install the stock throttlebody and see what that does,
else if could be the motor or the TB that is at fault or

Not the wires themselves but weak crimps of the male pins is common faults

You may have to get a tool that would allow popping the pins off the wiring connector and re-crimp them
Really a good OBD-II scanner looking at the DBW values would help debug the problem
and the scanner would allow looking at TPS on the TB and see if the reported angles look correct such as
with just key on but engine off TPS should report like maybe 6% butterfly open angle
and slowly stepping on gas pedal and see if the angle percent smoothly goes to 100% and when getting off the gas pedal returns back to 6%

Else that 3rd party TB is at fault and going back to stock one solves the problem
I would not trust 3rd party gas pedal either as if the margin of error is small, 3rd party one is out of GM design spec

 

[jeff.james66]

Hello,

Thank you so much for your reply. You have got to be the first person I've spoken with that really knows what they are talking about. I do not own an ODB-ll scanner the codes I can get are from my Diablo tuner. It does a good job at displaying codes but that's it. No values as far as the sensors go. So, today I went out and cleared the codes and started the car. It Idles ok and let me rev to about 3k ok. As soon as I revved past 3k it went to limp- check engine, reduced power, ABS, etc. This time there were more codes.

ECM0122: Throttle/Pedal Position Sensor /Switch A Circuit Low
ECM0222: Throttle/Pedal Position Sensor /Switch B Circuit Low
ECM1516: Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance
ECM2101: Throttle Actuator Control Motor Circuit Range/Performance
ECM2135: Throttle/Pedal Position Sensor /Switch A/B Voltage Correlation

Previously when I touched the TB connection it would make a funny noise like a vacuum motor or something that sounded like it was coming from front of car, then it would instantly go to limp. I guess that's what its called where it displays all the check lights and reduced power, feels like its running on 4 cylinders. I did change the Throttle/Pedal Switch, actually replaced under warranty by Orileys Auto Parts. The last one was replaced back in June. It resolved the issue at that time till now. I couldn't really tell any physical difference in that one and the new one.
I also have a Nick Williams TB if that makes any difference. I feel like it may have had a bad connection because when I would touch the wire harness on that side it would do the limp thing. So I checked the plug and used a small screwdriver from the back of the plug I gently pushed each terminal to make sure the pins were making good contact. After that is when I was able to rev to 3k but once revved higher that's when I got the 5 codes listed. So your information about the TB Butterfly makes a lot of sense. I may need to return the pedal and get a genuine OE part.

Thanks again for your help,

Jeff

 

[jeff.james66]

Thank you again, can you recommend an ODB-ll that does DBW that wont cost me my first born. and lastly, you mentioned (Also assure the TPS is sync'd with the PCM and might need a TPS/PCM relearn process) Can you advise TPS/PCM relearn process.
One final thing, I think I posted this in the wrong forum. Should be in C6 Z06 - Pit Road not C5. any way to relocate?

 

[lsu-vette]

Replaced Petal position sensor, cleared codes, error came right back. Instantly puts car into limp mode, reduced power, no traction control, no power steering. Basically running like crap. This is new motor. LSX 440, Wiseco Pistons, Eagle Rods, Comp Cam & Lifters the works. Any Ideas?

 

[lsu-vette]

Just a thought.. did you check ALL of the grounds? I had a similar problem and it turned out to be a bad ground near the left rear fender.