#25,21 and 13 cel's HELP!!

[Mike Marnik]

OK so i keep getting Barometric Pressure sensor, Coolant Temperature Sensor, and Air Temperature Sensor CEL's. If i Clear them they come back in that order if that means any thing. Also when this happens my knock sensor pegs out at 42-43 all the time the tps will not register any change in throttle position. All those sensor are on the same section of the wiring harness and i replaced the wiring that goes to the sensors on the thermostat housing and i replaced the coolant temp sensor. the knock sensor is also brand new and i check the tps with a ohm meter and its good. It also comes and goes it is strange it will run like a champ no cels for a few days then out of nowhere bam i get the cels and all those sensors and what not go out. I am at my wits end its gotta be something simple since its all on that section of the harness but i cant for the life of me figure it out please help me I'm away at college and want to get it fixed before i go back home tomorrow. thanks.

 

[Old Mitsu Tech]

You are going to need to scan to see the actual numbers. The tps intrigues me. You are saying that it won't register change with key on engine off and stepping on the accellerator? I would check reference voltages. Sometimes the 5volt reference will get shorted and affect other sensors. Check 5 volt at tps and then check the output while sweeping. I recommend an oscilloscope. This can also check for transient dropouts. Check all your reference voltages. This is a quick but important story. On a GM vehicle I had a no power situation which finally were traced to a damaged ac hi side cutout switch wiring. The wires had gotten together inside the loom. Looked like someone had cut and twisted them together for some reason I will never understand. The 5 volt reference was also on that line and it instantly killed the TPS and the MAP sensors. I had no 5 volt reference at all. I first replaced the pcm to no avail. Finally with the help of a friend who's an electrical genius I learned to check every thing that could kill the reference and had access to that circuit. It's the little things that will get you. Check everything on that circuit very closely. Wiggle wires at the connectors as sometimes they will break right at the connector. Observe your meter of choice, be it a scanner, dmm or scope. This has the possibility of a very quick cure or long term hair puller. Let me know what you find. I hope this helps

 

[Mike Marnik]

what is the 5 volt referance? and i just checked the tps the other day with th eohm meter and it was fine and that was after the first incident of it coming and going i even moved the throttle and it went up like its supposed to. its like its not getting power or something to the sensors to send back a signal. none of the sensors that come up in diagnostic on my logger send any signal at all. im in college right now and dont have any thing to check the sensors with but i may have a friend that can help me out. as i said i just replaced the 3 plugs that go to the sensors on the thermostat. and it will work correctly most of the time all i can think is its a bad connection or something way down the line because all of the sensors going bad are along the same section of the wiring harness. this is definatly becoming a hair puller. also where would the reference circut be im a little confused on exactly what that is my electrical skills are not at par with my mechanical yeti can only wire things. thanks for the reply.

 

[Mike Marnik]

ok so i went far back on the wiring harness and found no frayed wires this is really pissing me off because i was supposed to go to the track tonight and well now i cant. The really weird part about all this is that it ran for 2 days perfect with no problem and today it decides to shit out on me again what could this be ecu going bad?? im really lost on this one. Oh and btw when i unplug the knock sensor during the problem it reads zero but if i give it gas any amout it goes up to 9 wth is going on please help.