CHANGED TPS CLEARED ECM NOW GETTING CODE 22 AND SEL IS ALWAYS ON.
1990 Pontiac Firebird
July, 14, 2012 AT 7:24 AM
I just bought a 1990 firebird 3.1L v6. Even though the SEL light wasn't on it had horrible acceleration even after a full tune up (plugs, wires, filters, timing, fuel filter, and welding up holes the previous owner put in the exhaust pipe to make the car sound cooler). The car runs at normal temp, but smells ric, and has major power lag, especially when going up any incline. Yesterday I had autozone check the codes and it had a code 22, I bought the new TPS and installed it right there in the parking lot. Now the SEL light is on al the time and the code it is throwing is the same code 22. The accelleration is slightly better, but not much. I thought maybe the tps was bad and exchanged it for another with the same result. Any help getting this car in working order would be greatly appreciated.
Just because you get a code for the TPS circuit, that does not mean the sensor is causing it. It can be anything in the circuit and it needs to be troubleshooted correctly
July, 18, 2012 AT 10:03 PM
Thank you for your responding. I would have responded earlier but I had some family issues to deal with. Anyway I tested the circuit and this is what I found. The signal wire comes in at 5.01v but neither of the other two wires have any current flowing through them at all. I was afraid that I may have been testing it wrong so I watched the video you linked to me the other day again and I was in fact doing it right. To be sure I tested the circuit again with the same results, then tried a second multimeter incase mine was malfunctioning, all with the same results, 5.01v for the signal wire, and 0.0 on the other two. I'm now at a loss, is there a fuse or something that I'm not seeing?
July, 18, 2012 AT 10:07 PM
Was the sensor unplugged when you tested that?
Did you test for opens and shorts in the wires back to the PCM?
July, 18, 2012 AT 11:04 PM
I tested it both with the sensor on and off. I only followed it back about a foot or so, where there was a place where it was obvious that someone had spliced the wires. Even past this point I got the same readings. On that note how difficult would it be for me to just rewire the entire thing, rather than chase shorts and opens?
July, 18, 2012 AT 11:15 PM
That's not how you do that. You have 3 wires. 5v reference signal FROM the PCM, a signal ground FROM the PCM and a signal return wire TO the PCM from the TPS. All you check was the 5v reference.With the sensor connected, connect your meter between the other 2 wires that didn't have 5 volts and read the voltage as you slowly sweep the throttle and it should gradually climb from about .6v up to about 4.5v.
To check for shorts and continuity you need to access the plug at the PCM (disconnected)and locate the other end of the wires and test for continuity in the wire and from the wire to ground.
July, 19, 2012 AT 2:13 AM
Ok I rechecked everything as prescribed and got 5v on the reference wire and.4 on both of the other wires independent of throttle position. At this point I had a buddy come over and he suggested we try the test again with the old tps. This time things went way better, the old tps went from.45 all the way up to 3.82v on the blue wire, the black wire showed no change at all regardless of throttle position. I'm thinking this probably means that the new tps was just bad, I'm going to buy a new one tomorrow and see if that helps.
July, 19, 2012 AT 2:18 AM
You're supposed to be measuring across those two wires, not measuring them independently. The signal wire will read varying voltage using the other wire for a ground for the other lead but it sounds like you may be on to something.
July, 19, 2012 AT 2:26 AM
I did attempt to measure them against each other and kept getting 0v regarless of throttl position that's when my buddy had me hook the negative to the chasis as a ground. That's when we started actually seeing voltage on the blue wire, with the old tps the voltage would vary with throttle position.
July, 19, 2012 AT 9:48 AM
That makes that sensor ground (black wire)suspicious although it is shared by the MAT sensor so I would expect issues from it also if there was a problem with that ground circuit.