Throttle Position Sensor Adjustment

ZZZZZR1 · 02-12-2002, 05:19 PM

I will be installing a new throttle body on my '94 ZR-1 this weekend. I want to adjust the Throttle Position Sensor as part of the installation. Either I'm not reading the factory manual correctly, or it doesn't specify from which two of the three TPS connector posts I should take the reading. I know that the reading should be .53 volts. Do I use the top two pins, the middle and bottom pins, or the top and bottom pins on the TPS connector?
:confused:
Thanks for any advice.

scorp508 · 02-12-2002, 05:22 PM

If it is the same as my L98.

The bottom wire is a 5v reference wire. You hook (+) to the top wire and (-) to the middle wire. :)

ZR1991 · 02-12-2002, 05:49 PM

Nick, I did it too, and can't remember. But I believe the first poster is correct. One is the input voltage, and the other will vary with the movement of the sensor. It should be obvious, as I remember.

In other words, only one will give the readings like you want. It will be apparent as you do it.

I would offer more, because I put notes in my service man, but since daughter's wedding at my house last fall, I can't find my book!

Ultra Slow · 02-13-2002, 12:19 AM

I have got one of those adapters to do just this. I'll look at it later and tell you the procedure... You of course dont need the adaptor, but looking at it will tell where to put the leads.

Rkreigh · 02-13-2002, 02:22 AM

the test adapters are worth it so you can just plug into the wiring/sensor. otherwise you need to probe the wires.

you check the idle volts, and wot. kinda have to fiddle with the TPS postions a few times to get both set to where they should be.

.53 is idle and close to 5 is WOT, I kinda forget. once you set it, it should be OK. will a misadjusted TPS cause the idle to "hang high"

my ZR1 seems to hang up around 1500, but only now and then. could this be a bad MAP??? or is it more chip calibration??? funny thing is, it only does it every now and then which make me think the TB is hanging open, I have the 63 MM blades.

Jeffvette · 02-13-2002, 05:23 AM

Hey Nick, where did you finally get the new TB from?

ZZZZZR1 · 02-13-2002, 12:59 PM

Thanks for the info, guys. Jeff, I bought a brand new one from a private party that I found on the ZR-1Net. He has several more left.
I'll have more on the subject of defective throttle bodies once I install the new one and verify that it works correctly. Fingers crossed for no more high idle! :yesnod:

scorp508 · 02-13-2002, 01:50 PM

I have the harness adapter also, makes it much easier. :) For what it is worth on my L98 I can set it as high as 0.68v at idle w/o setting a computer code. It gives an every so slightly more snappy throttle since the TPS starts a little higher up in the throttle signal.

shera · 02-13-2002, 10:19 PM

Guys from 1990 to 1996 the Throttle position sensor is auto zeroing and does not need adjustment. This is done electronically, so just install the new one. Isn`t progress great!!

ZZZZZR1 · 02-14-2002, 01:30 PM

Not according to everything I've read and heard, nor according to my 1994 shop manual. Auto zeroing? The correct adjustment is .53 volts at zero throttle, to my understanding.

[Modified by ZZZZZR1, 8:31 AM 2/14/2002]

shera · 02-14-2002, 03:11 PM

I thought the same thing since the last vette I had was the L98 with an adjustable throtle position sensor. Adjusted just like you are taliking about.

Then i got my LT5 and wanted to check the voltage of the TPS which I can do with Diacom or a digital volt meter.

I looked it up in my book and came accross the "auto zeroing" feature.

The sensor is not adjustable in the ZR1. Maybe someone else can chime in.

[Modified by shera, 1:58 PM 2/14/2002]

ZR1991 · 02-14-2002, 06:50 PM

I agree, at least for the LT5, the TPS is not auto adjusting, but the IAC is... sort of. That may have been what some have seen.

Ultra Slow · 02-14-2002, 06:55 PM

To check your throttle position sensor without the adaptor,

Use a volt meter... Of the three wires going to it, probe the center one for positive to your meter, and the upper one to negative. You should set to .57 or darn close by a very slight adjustment with the throttle all the way closed.

The motor does not have to be running for this, just the ignition on.

Rkreigh · 02-15-2002, 09:02 AM

what is the correct WOT voltage. near 5 volts??? I have done the TPS resets on my other cars but never the vette. I have a strange problem. lately the RPMS stay at 1500-1750 and take a long time to come down. near as I can tell the TB isn't hanging up (it's a 63 MM). might be time to clean up the IAC??? others have told me it's the chip calibration, but since the problem comes and goes I suspect something else.