losing throttle input
11-25-2012, 11:57 AM
#1
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losing throttle input I posted this in the tuning forum but i'm not getting any responces. i'm hoping someone has experience with this problem.
I have an 04 LQ4 out of a Yukon. It has the stock wiring harness, TAC, Pedal, and Throttle body all from the original donor vehicle. I had Wait4ME performance mod my stock harness and do my tune. It wasn’t much of a tune just deleting vats, rear o2 sensors Ect. I am also putting a manual trans behind this motor, so I asked Wait4me to delete the automatic stuff in the computer.
I can start it and drive but if I put more than about 20% Throttle then I lose all input to the motor and it just idles. I can turn it off and wait the 6 seconds and start all over again. I’ve changed out the throttle body, TAC, and the Pedal one at a time. All with the same result. I called Jess at Wit4Me he said he wasn’t sure because you can’t turn the pedal function off in the computer so it had to be somewhere in the TAC , Pedal, Throttle Body loop. I checked the TAC to the pedal harness lastnight and it didnt show and damage to the wires, but it just carries the signal from the APP to the TAC. which it does. I also asked Jess about the Automatic sensors, and if the computer is expecting some input that it wasn’t getting so it shut down as a safety feature. He said there wasn’t anything that would do that. I have hooked a Tech2 up and it isn’t throwing any codes, I’m not sure what else to check or change out. Does anyone have any ideas on what to check next? Thanks for your help.
Ian
I have an 04 LQ4 out of a Yukon. It has the stock wiring harness, TAC, Pedal, and Throttle body all from the original donor vehicle. I had Wait4ME performance mod my stock harness and do my tune. It wasn’t much of a tune just deleting vats, rear o2 sensors Ect. I am also putting a manual trans behind this motor, so I asked Wait4me to delete the automatic stuff in the computer.
I can start it and drive but if I put more than about 20% Throttle then I lose all input to the motor and it just idles. I can turn it off and wait the 6 seconds and start all over again. I’ve changed out the throttle body, TAC, and the Pedal one at a time. All with the same result. I called Jess at Wit4Me he said he wasn’t sure because you can’t turn the pedal function off in the computer so it had to be somewhere in the TAC , Pedal, Throttle Body loop. I checked the TAC to the pedal harness lastnight and it didnt show and damage to the wires, but it just carries the signal from the APP to the TAC. which it does. I also asked Jess about the Automatic sensors, and if the computer is expecting some input that it wasn’t getting so it shut down as a safety feature. He said there wasn’t anything that would do that. I have hooked a Tech2 up and it isn’t throwing any codes, I’m not sure what else to check or change out. Does anyone have any ideas on what to check next? Thanks for your help.
Ian
11-25-2012, 12:00 PM
#2
Check the harness connection at the throttle body and at the TAC module. Use a scanner and monitor throttle position/voltage while wiggling these two connectors one at a time.