Changed intake gaskets, now P0121 TPS performance code !
Hi guys, I changed the upper and lower intake gaskets on the 1997 3800 Series II the other day. This obviously involved removing just about everything on top of the motor. I took the throttle body off the manifold to clean it out w/ throttle body cleaner, and I took the TPS sensor and IAC off at this time. The TPS on my engine is not one of the adjustable ones, it just screws on. When I got the car back together, it ran great but threw a P0121 TPS range/performance fault code. I reset the code, and the car drove w/ no problems for 150 miles. Then, suddenly, when I stopped over my friend'* house and came back to start the car, the code came back on. I replaced the TPS, reset the code, and just drove 230 miles, with no problems or check engine light. Just as I got back to my apartment here, I shut the car off, restarted, and voila, the P0121 TPS range/performance fault code is back. This is driving me nuts. Any suggestions? I know there is a tiny bit of play if you loosen the screws, you can swivel the TPS a tiny tiny bit (not at all like the adjustable ones). Obviously I must have the TPS installed clocked slightly different than it originally was, but I can't believe with a new sensor that it still has a problem. Can anyone tell me how to check the TPS w a multimeter? I know that I'm looking for no discontinuities in the variable resistance as I sweep the TPS range, and that the max value, key on, should be around 4.35 volts. What wires am I installing jumpers on to check the sensor?