Erratic TPS readings
TPS reading is all over the place. Sometimes it’ll stay at zero and I can get the IAC to stay between 3-10 once warmed up. Other times the TPS will jump into the 40s and 50s. This will show on the monitor with the ignition on prior to starting as well as while running. Replaced with an AC Delco TPS and it does the same thing. You can see more fuel coming in when this occurs with the throttle still closed. This system is driving me nuts. It’ll run smooth sometimes and then other times my truck is barely driveable.
Try this test. Turn ignition to on position and dont start the car. On the handheld, look at the TPS reading when you are pushing on the gas pedal slowly in and out. It should vary from 0 to 100. If it still giving you erratic reading , then try removing the TPS sensor from the throttle body, but keeping the cable attached, and try manually turning the sensor so see if you still get erratic readings. If you do get erratic readings it is ether the sensor ( even though you put a new one on), wiring , voltage to the sensor, and worst of all the ECU. Also what model do you have?
I have the Go Street 400HP EFI.
I tested to see what the TSP reads with pwr on yesterday and it goes smoothly up and down through the full range. I had tried to run a few data logs when the issue was occurring, but I must’ve done something wrong. Currently having no issues with original TPS back in it, readjusted the IAC with the TPS signal showing 0 and it’s running pretty good.
Quote from mbyoung424 on August 21, 2021, 1:05 pmI have the Go Street 400HP EFI.
I tested to see what the TSP reads with pwr on yesterday and it goes smoothly up and down through the full range. I had tried to run a few data logs when the issue was occurring, but I must’ve done something wrong. Currently having no issues with original TPS back in it, readjusted the IAC with the TPS signal showing 0 and it’s running pretty good.
Now that it is running fine again, you may want to reset learn as learn values may be off. Fitech recommends that when the EFi throttle body is running bad due to faulty sensor, injector, etc, you should reset learn values
Erratic TPS issue continues. Without going into all the issues, the problem turned out to be a bad ECU.
Wasn’t getting much help by emailing FiTech, but they did give me an update from 4 years ago. Didn’t make any difference.
Got someone on the phone and they identified the issue in about five minutes. Unplugged the TPS and tested voltage on the plug with the key on. Grey wire shouldn’t have anything as it’s the signal wire from the sensor, blue is pwr and should be 12V and the black is ground so shouldn’t read anything. My ground was reading 5V and my pwr was jumping between 12-15V.
I was told I can take off the side panel to check for any frayed wires, but I don’t know how they’d be damaged when they’ve never been touched. FiTech said they can fix the ECU for $319 plus shipping and takes about 1.5 weeks from time of receipt.
Quote from mbyoung424 on September 11, 2021, 11:32 amErratic TPS issue continues. Without going into all the issues, the problem turned out to be a bad ECU.
Wasn’t getting much help by emailing FiTech, but they did give me an update from 4 years ago. Didn’t make any difference.
Got someone on the phone and they identified the issue in about five minutes. Unplugged the TPS and tested voltage on the plug with the key on. Grey wire shouldn’t have anything as it’s the signal wire from the sensor, blue is pwr and should be 12V and the black is ground so shouldn’t read anything. My ground was reading 5V and my pwr was jumping between 12-15V.
I was told I can take off the side panel to check for any frayed wires, but I don’t know how they’d be damaged when they’ve never been touched. FiTech said they can fix the ECU for $319 plus shipping and takes about 1.5 weeks from time of receipt.
I would take off the side cover and the ecu cover to inspect TPS wires to see if they somehow got pinched or the wire coating is bad and exposing inner wires which are touching a live wire. It is made in China after all and they dont have the quality control unless they are being watched. You could also cut the ground wire from the sensor wire and solder it to another ground wire to see if that fixes it since there is five volts on it and the ground wire may have been improperly soldered to the ECU.
That’s a brilliant idea. I’ll try that out tomorrow. Thanks.