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Ended up finding the problem was mechanical and not electrical. Throttle body shaft was broken in two.
Overlooked this.
The tb. Is 100mm. But shaft looks like a stock piece. I pulled it out welded it up for a temporary fix until I find a new shaft.
That shaft looks HORRIBLE! I bet it was binding when going to the idle position and setting off the Accelerator vs Throttle Position Sensor position voltage variation. That will cause REP.
Hey, when you get the new stuff in installed, take the old stuff apart and take some pictures. What did the front of the shaft look like? Looks like someone was trying to thin it out for more air flow. I'm hesitant on doing a lot of grinding on the shaft when I port TBs. Its for that very reason.
My c5 98 has been in the garage for the past four months waiting a solution from its dedicated owner. I live in Brazil, and there are no parts for corvettes available in the country, so I have to wait for some months to get parts I order (for friends to go to USA and bring them). Codes are P1125, P1275, P1280, P1285, all suggesting my pedal sensor is bad. So far I have already opened the pedal sensor and because i opened it, I broke some traces and they had to be repaired with conductive ink. The resistance from the three sensors seem to be working ok. Then I bought another pedal sensor when I had enought of trying to fix it. No good. Bought another used tac (newer) and problem continues. I tested continuity for all wires from pedal to tac, and they seem ok. Tested continuity from other connector that gets to tac (cruise wires, throttle actuator motor, tps sensor, 12v, gnd and data link to ecu) and they are showing continuity. I then cut out the connector of the pedal sensor and the connector of the tac, redid the connection bypassing car harness and problem remains. I then cut the wires from cruise that arrive at the tac to see if they are causing some badly diagnosticated problem within tac and nothing got better. Just got another code for the cruise. I took out the tps sensor and tested both sensor terminals and they have a varing reading according to position, approx 3.5k ohms to 0.6k ohms. Then i took the throttle body out and disassembled the actuator motor. It is spining freely. The reduction gears are good, even though the spring that keeps the butterfly closed is very strong, which made me think that maybe the tac module would not be able to handle the current the motor will require. the motor will spin continuously if attached to power out of the body (I tested with 5v, but I believe the Johnson motor is rated 12v). In the car the motor is producing a fine continuous beep for 1/2 a minute when key is turned to ON, I guess this is a result of the frequency of On and Off the Tac module produces (pwm) to keep the motor in the same position. After a while the tac module takes out the power and butterfly closes with power from the spring. I was wondering if tac was not talking to ecu, but it is, as the cruise codes set when I cut its wires. I have hp tuners but unfortunatly it does not show the individual reading of the 3 pedal sensors. The service manual indicates that the official gm tool would read the disagreeing parameters. I am out of ideas. I am considering to bypass all connectors and make a direct connection from pedal sensor to tac and from tac to motor, tps sensor, batery, gnd and ecu data, but i have to find a suitable replacement connector for that purpose. Also wondered if it is possible to intercept the dedicated data communication between tac and ecu to try to see how it works... If replacing the tac was not enough would it be advisable to buy a new ecu? Or should I try to replace the throttle body first? I dont have codes for the throttle body but I believe the motor could be causing some strange behauvior of the tac board if the current is too much...
rdelboux, I understand you're new here (2 posts) and that you live in Brazil. Let me assist you briefly. Your above post is tacked onto a thread from another user and yours will have a tendency to "get lost" because most of us understood that the original poster found his problem and the issue was resolved. So to help us help you, please start a new thread and post your message there. Give us as much info as you can. By starting a new thread, we'll be able to address your problem and yours alone. Let us know what the exact problem is, codes you're getting and we'll go from there. You sound very experienced, which is good.
Last edited by CactusCat; Jan 3, 2016 at 12:22 AM.
In addition, did you not know just how easy it is to remove a terminal from a connector/ Much easier and better than cutting wires that have to soldered and sealed.
thanks gentleman.
