Problems after rinsing off my engine...

[theriddler]

I knew better but did it anyways. I rinsed off the engine of my '99 4runner and developed a transmission shifting issue. When driving down the road the transmission refuses to shift gears, we're talking like 4000-5000rpms before it shifts. Assuming it was water in a connector somewhere I unplugged every connector I could find in the engine and sprayed electrical contact cleaner in it and then dried it with compressed air. No fix yet, but I did find that when I unplugged the TPS sensor it drives and shifts fine, but will no longer downshift. Plugged the sensor back in and it continued to shift at high rpm. I put the TPS on a bench with a 5volt power supply and measured the output voltage and it read from about .5v-4.6v That sounds about normal but there was a slight fluctuation on the voltage sometimes and it didn't always return to .5v like it should....sometimes it'd return to .8v A new one is on order now so we'll see what happens when it gets installed.

Also had a pecking noise after rinsing off the engine as well, turned out to be newly installed spark plug wire coming off. Water blast must have hit it just right (or wrong). Didn't throw a code since it was still getting spark to the cylinder...just a weak spark.

 

[scrap metal]

You should observe the voltage of the tps sensor as you slowly open and close it as well. The voltage should be linear... any weird jumps or erratic fluctuations indicates it might be bad.

 

[Andywear]

How bout disconnecting battery for awhile so computer resets?

 

[theriddler]

I checked the resistance with the TPS removed from the engine and tested it again at work on a bench with a power supply today at work. It was acting funny, wasn't always linear and didn't always return to "0".

I did however disconnect the battery after every troubleshooting technique I went through. The TPS consistently gave me problems when it was plugged in so we'll see what happens with the new one when it comes in.

Thanks for the responses and advice!

 

[Andywear]

Im curious cause was planning on washing my engine bay next time but this has me doubting its a good idea.

Ive washed a lot of engine bays at the car wash, Corolla, Tacoma, Wrangler even a motorcycle. On the cars I used a plastic wal-mart bag to cover computer. Never had any problems.

 

[theriddler]

Im curious cause was planning on washing my engine bay next time but this has me doubting its a good idea.

Ive washed a lot of engine bays at the car wash, Corolla, Tacoma, Wrangler even a motorcycle. On the cars I used a plastic wal-mart bag to cover computer. Never had any problems.

Me neither, but most of my Taco's were only a couple years old back when I was off roading on rinsing the engine bay after every run. I don't think I'll do it again unless absolutely necessary, the return isn't worth the risk.

I'm kinda excited to test the new TPS now, if it works I may be able to customize the "ECT" button for a custom hot mode. It drives normal without the sensor, just doesn't want to downshift. With sensor plugged in it drives like a race car and shifts at 4k-5k rpms and downshifts at the slightest command. I may be able to add a resistor to the circuit to make the ECT Power function a little more aggressive if the new one works.

 

[Andywear]

that sounds cool.

 

[theriddler]

Happy ending...TPS sensor installed and functional, truck shifts fine now

So I got the new TPS sensor installed yesterday and it worked like a charm. After disconnecting the battery, installing the sensor, and reconnecting the battery the fault code went away and it drove and shifted like a dream. Although shifting at 4-5 thousand rpms while giving it hardly any throttle was fun at first, I'm glad to have it back to normal.

Lessons learned:
1)rinse off engine with caution and at your own risk
2)just because there is no check engine light doesn't mean you don't have a bad sensor.
3)testing the sensor with a power supply on a bench it didn't seem bad, although I saw some fluctuations in the voltage overall it seemed like it should have worked. Idle voltage on the sensor ranged from .4V-.8V and wide open throttle read 4.6V consistently. Maybe the heat or vibrations from the engine had something to do with it, I don't know. It wasn't perfect so I replaced it and it worked, this circuit apparently doesn't like anything out of the norm.

I feel better now as my last resort was to probably buy a OBD scanner or take it to the dreaded shop for analysis on their computer. Hope this helps out someone that may have the same problem.