TPS issue-kinda long story

[fridgeguy]

I just washed the engine in my Camaro, dried it off as best as possible with compressed air, mostly just to get the water of the fenders and in the middle of the RPM AIR GAP intake. I went to start it, it fired but stalled right away and then would not start. Eventually I got it going after it sat for a few mins but once I got it going the TPS was reading something 66% at idle and was very slow to respond to throttle imput. I re-set the TPS and idle setting and it would read 0 and seemed to be accurate with throttle imput but maybe a little slow. I then took it out for a test drive and TPS % was 0 and did not move and the engine was very sluggish and seemed to want to stall. A/F ratio is ok. I disconnected the TPS and it did code and I was able to clear the code once it was plugged back in. The car ran fine this morning on a 40 drive prior washing the engine. There is no water in the TPS plug.

[bluzman2004]

I had a 91 throttle body 305 camaro and washed the engine and had the same thing happen. I believe this is the same TPS sensor that that was using. I don't know if they are actually fully water proof or not. It is just a GM TPS sensor, so it could be that. I replaced mine and everything was fine. Might see if it dries out.

[fridgeguy]

Thanks fior the quick reply Ron. Do you have the GM part # for the TPS and I'll give that a try.

[fridgeguy]

I changed out the TPS and no difference, reads 0 regardless of throttle position. The part # i used is the one posted in another thread on here. It is not have the same part # and the on the throttle body but looks the same. I did have a TPS code with the new TPS that cleared. What next?

[bluzman2004]

I would check and make sure you have 5 volts and ground on the TPS connector. You will see in the back of the instructions a wiring diagram that will tell you what letter the voltages should be on on the TPS connector. If they are both there, then plug the TPS connector back in and measure the voltage at the signal pin and see if you are getting a voltage sweep as you move the throttle. The car power has to be turned on to do this.

[fridgeguy]

ok I'll give that a try. Which wire is the signal pin and where do I check this on the harness. I'm a little green at electronics but learning.

[bluzman2004]

On the TPS connector it is the white/red wire in position C. There is a wiring diagram of the entire harness in the back of the instruction manual with all of the pin letters/numbers and wire colors, too.

[fridgeguy]

Thanks, I think I've got the diagram figured out. I have some pretty good diagnositc technicians in my shop and I think we'll get this figured out. I tried a new TPS and it codes at aprox 1/4 throttle application and the hand held stays at 0 % regardless of application. I'm going to try another one just to make sure I don't have a bad TPS. The guts of old TPS fell apart. I drove it for aprox 10 miles still plugged in with no code. I'll let you know.

[fridgeguy]

here's the results I got
white/red (c) wire .6 ohms closed,.010 ohm throttle wide open
red/white--5 volts at close and open with no voltage change during transition--TPS would code as soon as I moved the throttle
black/pink wire has 24 ohms
Hope this makes sense

[bluzman2004]

You should be able to set you meter to read DC volts and ground the black lead. Then, with the key on, check each wire before it is connected to the TPS sensor. One will show 5 volts, one will be a direct ground, and the signal wire will be floating or close to ground probably. Then when you plug it into the TPS sensor, the signal wire will read a voltage lower like .32 or something at idle and when you move the throttle to WOT it will read something like 4 volts or something close to the 5 volt reference.