hey_obie

82 has been running rich. Trying to test the Throttle Position Sensor. Looked in the manual and can't find a thing. Looked on the board and found some info.

What I read: There are 3 wires on the TPS. Black is ground, white is a 5 volt and the BLUE wire varies depending on gas pedal.

My 82 with key in on position, car not running:
WHITE wire - When I connected it read 5.6. As I stood there for 4 minutes or so, it worked it's way up to 5.97. Is this normal or is it bad?
BLUE wire . When I connected it, it read .49 and it gradually moved up to .57. When I pulled for full throttle, it read about 4.8-5.0 which is normal.

What should the setting be on the BLUE wire with no throttle (the idle position)? .50 or 0?

hey_obie

I just went back to check the TPS readings again.

WHITE wire now reads 7.45. I do not think this is a problem with the TPS. The TPS should be getting 5 volts, not 7.45. The BLUE wire is the responsibility of the TPS

BLUE wire now reads .65 It went from around .49 to .65 by just sitting there. I think the WHITE supply wire is causing the problem.

Am I right? Any thoughts are appreciated

They keep going up. Just like BP oil estimates and unlike the stock market.

MN-Brent

Its possible the regulated 5V coming from your ECM is bad. That would mean you have a bad ECM. If you have electronic technical capability, you could go into the ECM and replace the 5V regulator component yourself.

If not, shotgun a new ECM. You'll need to hold onto your existing PROM from your ECM if you go and get a replacement.

terry82

http://crossfireinjection.net/they have a how to section to test your tps .if you are running rich i would look at 02 sensor or the coolant sensor on the front of the motor.

hey_obie

Terry - I took your advice and replaced both the coolant sensor and the O2 sensor. It still looks like it is throwing a lot of gas in both injectors. I will check my miles/gallon after I drive 200 miles. The O2 sensor was covered with a lot of black crap from running rich. Thanks for the url. I read that years ago and couldn't find it on this site.

Brent - I would like to replace the component. My father is an electrical engineer and can replace the component. Can you tell me what to buy so I know which to replace? Thanks

MN-Brent

I don't have an ECM schematic. You would need to trace the voltage back to its regulator. Its 1982 technology, so its not going to be too sophisticated. Most likely a 7805 type device. Look for a 5V regulator circuit, probably an area that has a few relative larger electrolytic caps nearby, possibly even a choke or two.

It might even be a solder connection of this device, long shot, but look for that as well.

terry82

http://shop.advanceautoparts.com/web...S_425837655___i dont know how to repair them but heres aplace that you can get one.have you looked for a vac leak ?have you checked the egr for leaks?to answer the original question i vote for possessed.

hey_obie

Thanks guys. Believe it or not, I have a buddy who has an 82. I'll see if he'll let me swap his computer with mine.

I will start to learn about testing the EGR. Haven't been there. Will also test the vacuum. Throttle bodies are good. I rebuilt them about two years ago and replaced the manifold gasket when I balance the TB's with a manometer.

terry82

the top plate that holds the tbs is what leaks the most .i looked and could not find any more problems with the computer light staying on.

hey_obie

Thanks for the help. I'll do an ECM swap and see what happens.

I pulled the EGR. It seems to work fine. I put air and vacuum on it and it seemed to hold.

Do you know what the idle RPM should be. My engine seems to be pounding to hard. When it is cold, it runs at 1500 and when it is warm, 1050.

terry82

you should be about 650 rpm in gear.its starting to sound like a vac leak.

MN-Brent

Its quite possible that you have multiple problems going on. The older the car, the more exponentially the possibility is that there are multiple problems on the car.

Check this article for:
Timing
Fuel Pressure
TPS setting
http://www.corvettefever.com/techart...ing/index.html

Vacuum leaks and a bad Coolant Temp sensor are the primary reasons for high idle.