Join Date: Nov 2001
Thanked 5 Times in 5 Posts
Re: how to tell a bad tps?
I don't have any experience with the 4.0, mine is with the sbc TPI but they should works similar.
You should be able to measure the voltage from the tps with a high impedance voltmeter, digital would be best.
To get the codes, you could always take it to Autozone, they do a free error code scan
If the 4.0 works like the GM, it could be a lot of things causing the problem. At WOT, the GMs drop out of closed loop and into open loop for power. Depending on how rich you have been running and for how long, you may have ruined the O2 sensor and not be going closed loop anyway.