Surging, odd shifting, etc.

[[ion] C2]

Today I went through an enormous body of water on the road, slowly, but it was the largest, deepest amount of water I've ever driven through. My exhaust tips were underwater. Drove seemingly normal immediately afterward. A few miles down (5+), I notice my car acting funny when coasting down and stopping at the light.

Symptoms
It surges at idle in neutral/park. Acts as if my throttle plate is stuck on 1-2% (it used to physically get stuck sometimes but was easily slammed back to 0%) so it idles in gear at like 1200. Also low throttle it doesn't want to shift until I get to higher RPMs, also seems to like avoiding locking up the torque converter.

Observations
Played with the throttle, definitely not physically stuck open. Looked for vacuum leaks. Unplugged the TPS and the idle dropped. Plugged TPS back in, idled at the normal amount (800 ish)... still a sense of oddity, but eh, I turned off the car. Turned car back on, revs high, idles high again. Unplug/re-plug TPS to reduce idle, then drove around a bit, does what is described above in Symptoms.

Possibly bad TPS, although this is a slightly different form of failure compared to the last time I replaced the TPS. I know the throttle body that I use is kind of screwy and will scratch/damage the TPS over time, so it is a high possibility that's what this is. I still have another stock one I can install..


I dunno what could have gotten wet at that depth that would cause this type of issue, very strange. Only sensors I know that might be affected are wheel speed sensors and the O2s.. and it's not O2 sensor related. Probably all coincidental. That tends to happen around me.

Ideas? 1st attempt will be TPS.

[a.graham52]

sounds like tps to me. there pretty cheap, why not just put one in it?

[[ion] C2]

I'm gonna buy one. I might as well take off the throttle body anyway, I was planning on getting a new gasket and copper spraying it but too lazy..

Last time my TPS acted up I replaced it with the one off my stock throttle body lol. The bad TPS looked physically worse than the stock TB one, ironically.

[Nate's Alero]

Not a tps those are all symptoms of a bad or failing iat.

[a.graham52]

im willing to bet its tps. when i first got my car the idle would hang around 2k at times, even going down the road. it was my tps. and if the comp doesnt know where the throttle is then it wont shift right obviously.

[[ion] C2]

I can 99% say it's the TPS. I knew it would fail, it was a matter of when. It's the stock one btw, 223,000 miles.

Edit: Acted completely normal today, lol. Car was on/off 10 times today, drove 80 miles, everything worked absolutely perfectly. Throttle sensing appeared spot-on.