Throttle Position Sensor Testing

[schfiddyfive]

So I've been having some weird running issues with my 92 Festy, and I'm beginning to think it's the throttle position sensor. I've been reading all over the forum ( yes I searched kthx ), and I read that if you disconnect the TPS and it doesn't change how the car idles, it may be bad. So I did that, and drove the car, and found it drives exactly the same. The ECU never threw a CEL either.

I took the TPS apart, and it appears to be just a switch for WOT and idle. Well, when I put it in the WOT or idle positions, and test the resistance across the appropriate pins, I get nothing. Not even a little tiny bit of connection shows up. Shouldn't I be getting SOME kind of continuity from the middle pin to either of the pins? I don't see how an electrical signal can pass, if my multimeter doesn't show any continuity.

Thanks!

[Team Lightning]

Dumb question, did you check the meter to verify that the batteries (in the meter) are good? Also could have a broken meter lead. Check by checking the voltage in a known working outlet.
I've had a couple of people that I work with get fooled by dead batteries/broken leads
in their meter.
But.. yes if the TPS is good, you should get some type of reading thru the terminals.
Reading should vary according to the position of the wiper on the coils.

[wybnrml]

If you disconnect the TPS I think it is supposed to make it have an unstable idle.

Haynes manual says:
To check the TPS, connect the probes of the voltmeter to the (-) and (+) terminals on the back side of the electrical connector and turn the ignition switch to ON(engine not running). The sensor should read .5 to 1 volt at idle. Simulate full throttle and the voltage should increase to 4 to 5 volts. If its not those voltages then it is bad.
To check the TPS reference voltage. Install the positive probe of the voltmeter onto the voltage reference wire and the negative probe onto the ground wire. There should be approximately 5 volts sent from the ECM to teh TPS.

TPS wires go
Top wire Reference
Middle wire (+)
Bottom wire (-)

Hope that helps, and Welcome to the forum.:hello2:

[schfiddyfive]

Thanks guys. Well, I hate to be such a damn noob, but I went an re-tested it, and I got continuity just fine. I dunno if my friend did something to the TPS sensor like cleaned the contacts or if he just had it on the wrong setting. Anyways, it seems okay now. I didn't get a chance to drive it yet to see if it's any better, but I'll let you guys know.

I guess I should have mentioned too that we swapped to a B6 longblock. Everything else though, is stock Festiva parts. I'll take it for a spin here a bit later and let you guys know if it is now working or not. :p

Thanks for the welcome! Great forum, by the way, lots of great information here!

[schfiddyfive]

Well, we figured it out. Replaced the cap, rotor and wires and now the car runs like a CHAMP! Ready to take the win! Thanks again for the quick responses.

[miami man]

when in the junkyard snag an extra tps