91 z28 with 355 superram. Car has been sitting for awhile and I went to start her up but she didn't want to stay running without giving it some gas. Would just die without pedeling the throttle a little. Pulled some plugs and they look fine. Also checked the cap and rotor. Check engine light would light up but was unable to pull any codes except the number 12. Rough idle too. Any ideas. Going to plug in my laptop Sunday and run tuner pro to see if I can spot anything.

 

First place I usually look, after you've checked the basics like plugs and cap and rotor, spark plug wires, stuff like that is my TPS or IAC. both of those have given me problems with rough, low idle.

 

Well I connected my laptop with data master 8d and it wouldn't show the TPS voltage or throttle percentage.

 

Test your TPS with a voltohmeter first and see if you can see changes in voltage at the sensor. If you can, I'd suspect your ecu is bad. Especially since it's not storing the code. That sounds like a computer issue to me.

 

Voltage at tps is 2.2v and goes to .4v at wide open throttle. From what I just read that's completely wrong. So bad ecu ?

 

If the range is wrong it could be the sensor itself. Does it travel smoothly through the voltage range as you turn it? Also I'm not sure what the voltage range is supposed to be. I'm not sure how to test the computer itself, might have to do some searching. I don't think it would be a wiring issue or the voltage would be weird.

 

Sorry just reread your post, if the voltage is wrong it possibly could be the wiring too. I've never had luck with figuring out wiring problems though. Do you have access to a known good TPS you could test it out on?

 

Checked my tps with a meter. Ignition on. Ground is bad. When I ground on the chassis the meter shows 5v from both the other wires with no change in voltage when I open the throttle. So idk what's going on

 

I'm going to swap out the tps sensor tomorrow. I'll just pick one up from oreily and see if it works

 

Well I tried 3 different TPS sensors and have the same results so wiring or ecu

 

I hooked up a ground straight to tps ground input and that seemed to be the issue. But I worried now of why that ecm ground quit working