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3rd Generation Camaros 1982-1992 Camaros

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Old 09-04-2013, 06:59 PM   #1
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Throttle Position Sensor Help!!!

Hey all,
5th Gen owner with a son who owns a 3rd Gen 92 RS and we have been wrenching on his car for some time now. His 305 was converted from a TBI to a TPI before we bought it. The previous owner hacked the engine harness to hell so we did a complete rewire with a Painless kit. The car is injected like the 87-88's so we wired it up to match. We have been getting, both before and after the rewire, really low readings on the TPS. Normal range for initial set is .55 volts, we can't get a reading anywhere near that, best we can do and see at WOT is .04 volts. Reading is taken from the middle wire. Voltage going in is correct, the sensor has a good ground and this is the second sensor we've put in. Both sensors give the same reading.

I'm requesting help from any of you Gurus out there.

We believe the out of range setting of the TPS is causing his car to stall out randomly. Right after a stall, turning the key off and on gets it started again every time. We think the ECU is loosing track of the throttles position and goes into a sort of safe mode and shuts the car down. Confirmation of that would be good to.

Thanks guys for any help.
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Old 09-05-2013, 01:32 AM   #2
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So you are getting 5V and 0V correct? Check the continuity between the ground wire and a good chassis ground. Check 5V continuity to another 5V sensor, like the MAP mounted on the firewall. If there is a high ohm reading, there is a bad wire somewhere between the ECU and the sensor, if those readings come back below 10 Ohms, they are fine. Take the sensor off and test between the 5V and output, and GND and output, and see what it looks like. The resistance should either rise of fall off gradually as you spin the sensor.

I had a metal shaving fall into the TPS sensor port one time, took me FOREVER to figure it out, since it was shorting all the 5V sensors out at the same time. Had a nice lope at idle though!!

If u need a diagram I think I still have some laying around.
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Old 09-05-2013, 01:39 AM   #3
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you can also check the pins at the ECU to double check. use a probe set or even a set of sewing needles to poke the back of the connector, and sit in the drivers seat with the DMM while you hit the gas pedal. you should have the older style ECU, with the 2 connectors. on the 32 pin connector, pin C13 (dk blu) should be TPS signal 0-5V, C14 (grey) is
+5V reference, and D2 (black) is TPS ground, along with coolant temp and air temp grounds.
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Old 09-05-2013, 08:50 AM   #4
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Thanks guys, will be checking these out. If you think of anything else please post it up.
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Old 09-08-2013, 11:27 AM   #5
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Ok reporting back...
We got 5v for the power lead..bottom wire when mounted to throttle body.

Not sure what was meant by 0v? Need more on that.

His car has a MAF set up, not sure if that makes a difference.

Tested the sensor and readings rose and fell for both tests noted above.

Tested the readings at the ECU connector and those are all good.

Just put another TPS sensor in, got slightly better max reading .11v but still nowhere near where it should be.

We are stumped again.

My son saw another post about adjusting the idle screw, but I just don't see that being any different than rotating the throttle. Didn't work anyway.

We currently have the 92 ECU running the car, and we did that because of the speedo setup. We have an ECU from an 88 IROC but we are not sure what would happen if we hooked it up.
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Old 10-20-2013, 05:56 PM   #6
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0V was just a reference to ground, as in there should be no voltage compared to battery ground. Sounds like the inside of the TPS is not turning. There are a few different styles of TPS for these cars, make sure you are using the right one. One has a slot in the middle, and one has a little metal arm that comes off the side. Its very strange that you arent getting a voltage rise. Do you have 5V on the power wire with the TPS unplugged and plugged in?
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Old 10-21-2013, 01:38 PM   #7
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Yup we have the correct sensor. At the sensor, we get 0V on ground and 5V on the bottom hot lead. Again on a new sensor, we just couldn't get the range coming out the center contact. Now I took it to my mechanic buddy and from the under dash the OBD connector he gets the correct voltage and was able to set it. I have no idea how that works.
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