TPS 4.66 volts.

So is it a bad thing if the Input voltage is 4.66 instead of 5.0? I adjusted the output voltage to 3.87, to get the required .83, but I was just wondering if less than 5.0 is ok...

I would say you need to clean up your grounds

I can clean the connector all day long...but where does the other end go? Is it at the dipstick with the battery ground?

I have a 90 4.0 ax15, don't know if same but FSM says 5.0/0.85.

How many volts at the battery?

About 13.

OK, that is plenty.

I will give you the TPS test route for the 90, should be the same.

What trans?

It's normal for there to be some variance on the TPS input voltage as the circuit ages.

However, you're not setting an absolute value at the output, you're setting a percentage value (17%? I'd have to check) of the input voltage. The input voltage comes from a reference voltage circuit inside the ECM, and if you set to an absolute value, the ECM will try to compensate for what it thinks is a false reading.

Short form? You're going to have to readjust. Not much - but it's going to be enough that the ECU knows what's going on (note that the HEGO works the same way, as does pretty much any other "variable resistance" sensor.

(1991-up HEGO sensors develop a voltage, working like an 'air battery' - and are therefore different. The reference voltage for the HEGO only applies to RENIX rigs.)

3.87 volts should be the output if I have my calculations correct.