I just got my rebuild finished. Motor is still a 350, crank turned 10 under. I now have the Comp Cam 224/236 .536/.555 on a 114 lobe sep. I had SES light on before I uploaded my new computer tune from MadZ28. I uploaded the tune, and the light was still on. It is DTC 22 TPS low voltage. I recorded about 800 counts using Datamaster, and my rpms were between 600-2000. My TPS voltage was at a constant .04 volts. The TPS% was at a constant 5.1. This was for the entire scan. My Blm's looked good between 124-132, but mainly at 128. I never got any knock it stayed at a constant 0.0. Any suggestions on how to troubleshoot my TPS issue?

While I had the motor apart and the throttle body off, I removed the TPS sensor and IAC to clean the throttle body.

My oil pressure is at 40 psi, and I am happy with that. It drops down to 22-26 at idle after warm.

Thanks:

ZMAN Z28

 

Any sensor issue should be started by seeing if there is votage and ground at the sensor. Check from the grey wire to the black wire for 5 volts when it is on and unplugged. It should be there however since you don't have MAP and other sensor failures.

Now measure the voltage from the black wire to the dark blue wire while you open and close the throttle. It should vary from around .4 volts to around 4.7 volts APPROXIMATEY.

If there is nothing on the grey wire, you got some work to do to find the problem. If it's not varying on the dark blue wire, measure it directly from the TPS connector. If it's still not there, replace the TPS.

 

He's got 0.04V on the dark blue wire, as far as the PCM is concerned. Could be a faulty blue wire, which would not show up by checking the voltage as indicated, unless he checks it at the PCM. Could be a faulty sensor. Could be the sensor isn't over the "flats" on the end of the shaft.

 

Sorry, but what are the "flats"? Is that the spongey washer thats between the TPS and throttle body?

I'm defenitely going to check for voltage on those wires. Is there a resistance check for the TPS? I assue that checking for voltage at the wiring harness connector is the same as checking from the PCM? Or is there a wire coming out of the PCM that should have voltage also?

Thanks for the help:

ZMAN

 

The throttle blade shaft is round. On the end where the sensor goes, the shaft has "flats" on each side so that it is sort of rectangular on the end. That rectangle need to fit into the opening in the TPS sensor, so it can rotate the sensor internals.

 

I had that installed wrong. I inserted that shaft into the sensor the correct way, but I still have .04 volts even after resetting the PCM. I do have 5 volts reference siganl. The Chiltons manual says if you have 5 volts reference and the blue wire is out of tolerence, then the sensory is faulty. So I am ordering a new TPS sensor from partsamerica.com.

Thanks and hopefully that is it:

ZMAN

 

Thanks for the help:

I check voltage and the blue wire was reading .04 volts. I had 5 volts reference, so I replaced the TPS and it is now fixed. I currently don't have a SES light.

Thanks:

ZMAN