Way Outta Control
Join Date: Sep 1999
Location: The Palouse
Thanked 3 Times in 3 Posts
Re: Can you adjust the TPS on a GM TBI???
1. There is little to no adjustment on the TPS assembly,
2. You've adjusted the Throttle Plates using the idle stop...
3. Now, if there's a problem, there's only two possibilities:[*] There are internal differences in the ECM[*] You'll have to install a resistor in line with the TPS to drop voltage.
4. Try the following:[*] Set Ignition to RUN, with the engine off.[*] Measure the TPS voltage.[*] Remove the screws on the TPS.[*] Remove the TPS.[*] What does the TPS measure at FULL REST?
5. If you can't get the TPS to measure 0.40 and 0.46 volts,
6. There's a problem as the ECM won't see the engine's at idle.
7. This would make me think that the ECM's bad,
8. And supplying too much voltage to the TPS,
9. And that can't be adjusted out.
10. If so, why?
11. My vote, is the ECM is questionable, at best.
12. Are all the other sensor readings within spec?
13. What's the TPS voltage at WOT?
14. Is it possible there's a wiring error?
15. On side of the TPS should be supply voltage,[*]What's this voltage?
16. The other side of the TPS should be Ground.[*]Are you sure you've got a good ground between the TBI and ECM?
17. Have you swapped ECM's and checked voltages?