[grndslm]

Just got a serious problem with my Sentra, and hoping somebody can answer my question(s) about replacing the TPS sensor/switch....

 

[grndslm]

Still can't post in the other forums, so here goes...

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Hello.... I've got a long story, but I'll try to break it down to its essentials.

- Bought non-running car.
- Replaced ECM/PCM and it started up right away.
- It started smoking, so I cut it off... presuming it was the head gasket.
- Poured in some Bars Leaks "Head Gasket Fix".
- Drove the thing for 30-40 miles with the heat blasting. Cut it off for the day.
- Next day, I drove it for 10 miles. As I'm a block away from the house, idling.... the car just cuts off.
- Crank it up again, and it stalls at idle... again. Manage to get it home by keeping foot on gas while braking.
- Look at Idle Air Control (IAC) valve, and it's got coolant all inside it!! Coolant got thru the motor, onto the wiring harness!!
- Took me a few days, but I figured out how to diagnose the IAC motor with a multimeter. The motor was shot.
- Also took me a few days of blow drying and patting/blotting the wiring harness plug with a napkin, before I figured out that I have an air compressor!! That cleaned the plug out good enough for me.
- Finally got new IAC valve, motor, & gasket.
- Put it on right after draining corrosive coolant w/ "head gasket fix". Flushed with hose quite a few times, then poured in distilled water and drained.
- Poured in distilled water one more time, then crank the engine. It starts and idles fine for maybe 30 seconds to a minute. Then it starts acting up and dies.
- Finally starts with the white smoke again, so I realize that the head gasket definitely is leaking and it wasn't leaking JUST from the IAC valve.
- I'm desperate at this point, so I pour maybe 1/3rd of the "head gasket fix" that I poured in the first time... just want to get trade-in value for this car at a dealership!!
- I tried doing the Idle Air Relearn procedure, but I can NEVER get the MIL to blink. I've done it maybe two dozen times by now!! It never blinks...
- Decide to check the IAC plug, and it looked wet... so I hurry to get the motor off, but it looks dry. Seems the gasket is doing its job for now, at least.
- Finally get to checking the OBD2 scanner, and it gives me two additional codes about the Throttle Position Sensor (TPS) -- P0120, P1705 -- from what I got before, which I'm largely ignoring due to the faulty IAC valve/motor, but they were O2 Sensor codes, "no activity detected" -- P0134, P0154.

Since the TPS codes are new, I've already purchased the TPS from Advanced for like $76 after tax (found a $40 off code) and it's available for me to pick up now.

I'm just curious, since I can't return this electrical part after I pick it up... how easy it is to replace the TPS on the throttle body. Some forums I've seen said that the TPS was "built-in" to the throttle body... and can't be replaced. Or it requires the dealership to "adjust" the TPS. How true is all this??

I checked the TPS harness wiring, and the first & third wires looked OK to me. The first (voltage check) appeared strong, but the third (continuity check) I couldn't get a solid "0" on the ohm meter when wiggling the harness. Not sure if this was just because it was difficult for me to connect to the pin or if measuring resistance will just jump around like that with a "thin" connection.

I checked resistance on the fuel injectors, and they were all right within specs, at close to 16 ohms.

Any other checks, or TPS installation procedures that I should be aware of before I pick up this non-returnable TPS??

And how to get the Idle Air Relearn procedure to work if the MIL won't blink!?!? The IAC valve actually came with a different set of instructions that are different from this floating on the internet and are actually much easier, involving a simple disconnect of the TPS wiring harness for like 5 seconds, then letting it idle for 20 seconds. Sounds pretty easy, but the TPS might be my entire problem???

Much thanks in advance!!

 

[i68k]

depending on the year of your b15, if you have 2001 or earlier, you can just replace the tps, not sure how difficult this is tho. if you have a 2002+, the tb is a sealed unit, so you cant just replace one tps, at least not without ripping it apart. basically, if your drive-by-wire, the tb is sealed.