I think that I already know the answer to this question, but hopefully someone here has more experience with these, and can confirm my diagnosis, or if I'm wrong, point me in the right direction.
The TPS in this '96 ZJ 4.0 reads 14.5% at idle, and maxes out at 75%. Power is down, and fuel consumption is way up. I plan to replace both O2 sensors, but I found this TPS issiue while I was checking out the O2 sensors. Is it safe to say that this TPS is worn out?
Yeah, I would say so. Replace that and it may fix all your issues
TPS will not go 0 to 100% in normal operation. (most TPS failures occur at cruise throttle openings)(unsteady sweep)
Isn't a 96 OBDII? Check codes?
Cracked exhaust manifold?
195° thermostat working right?
Sanity check on MAP sensor IAT and CTS?
Have you got a voltage pid instead of percent? Idle to full throttle should run from roughly .5v to 4.5v. A tps seldom fails at the outer end of the range. 99% of the time, they wear out right at the spot they sit during a typical cruise. They go open for a moment, the ecu sees that, and you get a buck or jerk from the vehicle. (See: Any Ford built in the 80's)
Are you sure the throttle cable isn't stretched, or the pedal bent? Have somebody stomp the pedal and you go out and see if you can push the throttle further open.
In reply to bentwrench:
Yes, its obd2. Has an occasional P0420 code. I realize that it may, in fact really need a catalytic converter, but I was going to try just changing the O2 sensors first, because they look like factory parts from 1996. But I could see a faulty TPS causing poor fuel consumption and putting the catalyst out of range. I know they don't go from 0 to 100%, but I would expect something like 5% to 95%
Bad TPS will often kill the cruise control and make the transmission shift funny. The best test is to hook a multimeter (set to volts) to the signal wire and with the key on, engine, off, slowly move the throttle and watch the readout looking for jumps and dead spots. They don't always throw a code.
Thermostat has to get to 190° for computer to be happy.
Coolant temp is critical
MAP and IAT is critical
Upper O2 is critical, bottom O2 is a monitor to verify catalyst operation.
While I agree that the tps won't read from 0% to 100% it sure seems like I remember the usual operating range being more like 5% to 95%. If it were me I would have a hard time not replacing it.
Kenny_McCormic wrote: The best test is to hook a multimeter (set to volts) to the signal wire and with the key on, engine, off, slowly move the throttle and watch the readout looking for jumps and dead spots. They don't always throw a code.
Streetwiseguy wrote: Have you got a voltage pid instead of percent? Idle to full throttle should run from roughly .5v to 4.5v.
^Do this. The only way to really test a TPS
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