Just trying to install a new throttle position sensor on a '90. Seems the one I had was the culprit when we ran a diagnostic as it was spiking pretty bad. The friggin thing just went apes*** on me in traffic let alone what it does at a standstill with the brake compressed. Car revs then returns to normal idle as though it almost "bucks" in traffic. Seems like the vettes tryin to cough up a hairball. Anyone have any specific directions for install/adjustment? I know it has to be "set" somehow with the screws/bolts, but it's all new to me. TiA.

 

I don't believe the 90 is adjustable. Just remove the two torx screws, disconnect the connector and replace. You might want to check the voltage at closed throttle and open throttle with a voltmeter or scanner.

 

I would highly recommend a service manual
It would answer this question and many others
I know mine has saved me a lot of grief and a lot of $$$$$$$

 

You're right. I don't think it is. Atleast not according to a Chiltons I bought a couple months ago. I just remembered I had it, turned to a page in Driveability and emissions controls and there it was(And yes, having one is definitely a lifesaver). All it says to do for installation is line the TP sensor lever with sensor drive lever on the throttle body and tighten to 18 inch lbs(2 Nm). My mechanic even told me, installation requires adjustment, which is obviously bs. The manual doesn't say any other installation procedures for any of the c4 years either. According to this, none of them should be "adjustable". You might be able to "test adjust" by wiggling/rotating the throttle body with the screws loose, but not by much from what I can see. All you really do is test the output voltage at WOT and Idle to make sure it rises steadily from the 0.5 mark seen originally at terminal B from what I can see. Any erratic jumps and you most likely have a bad TPS. I wonder why in the f*** my mechanic said it needed to be adjusted if its an installation of a new unit. Do any c4's have a TPS that has to be adjusted?

 

LT5's do, I am pretty sure LT1/LT4 do as well. They have to be adjusted to a certain voltage range. A Helms service manual should be the next thing on your wish list, scrap the Chilton.