Testing TPS

[Bruce Allert]

Can the Throttle Position Sensor be tested other than unplugging & driving? I found when I unplugged it I could hardly keep it running. I tested the Cylinder Head temp Sensor when it was cold and found it to be in the 2500-3500 range. Also found the coating on the wire to be extremely brittle. Didn't test it when it was warm due to very poor running. I have a TPS on order and will get it this afternoon and am thinking on a new Head temp sensor too.
One more thing, is the other temp sensor (I think it's #1) located very near the dizzy?
bruce

[Bleyseng]

The other temp sensor is for the cold start valve mostly. It tells the ECU that it is cold enough to turn on the cold start valve when starting (below 40')
If the insulation on your CHT is brittle it is probably bad so replace it, they're fairly cheap but important.
Why test the TPS? Take it off and pop off the cover and look at the tracings to see if they are worn. Look for groves/lines in the brass strips, if so toss it. A new one makes for smooth engine operation.
Geoff

[Bruce Allert]

Thanks Geoff, I've looked at the tracings and they are deffinetly there... quite heavily! I'll pick up the head temp sensor too and, hopefully, this will solve my problems so I can drive the Punkin to JP's.
bruce

[pbanders]

Originally posted by Bleyseng
The other temp sensor is for the cold start valve mostly. It tells the ECU that it is cold enough to turn on the cold start valve when starting (below 40')

The other temp sensor is the air temp sensor. It is used by the ECU to correct the mixture for the varying density of air with temperature.

The CSV system on all but the 75-76 2.0L's is totally independent of the ECU in operation. The CSV turns on when the thermoswitch is activated by low temperature. Most thermoswitches don't turn on until the temperature is well below 32 deg. F, some not turning on as low as until 5 deg. F or so.

The 75-76 2.0L's have a connection from the ECU to the thermo-time switch, offhand, I can't recall exactly how it works. But I'm pretty sure that the temperature switching is still done by the thermo-time switch and not the ECU.

[Dave at Pelican Parts]

TS1 does not contribute an awful lot to the mixture. TS2 does...

The 75-76 TTS gets power sent to its heating element from the ECU. I think the ECU does that as soon as it gets power and does not vary that at all.

As a further note, the CSV should only spray fuel while the starter is cranking--if the temperature is low enough. It should have zero effect on a running car, unless it is leaking.

--DD