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Discussion Starter · #1 ·
My tahoe spent some time underwater and I think I've just about got things back to normal (haven't drove it outside the neighborhood yet though) except a high idle.

The engine did drink some water. I pulled the plugs out and ran the starter for a while. I changed the oil, sprayed wd40 in the cyls and waited until the next day to try and start it. It started fine the next day when I put the new plugs in.

Then the day after that it started idling 1500-2000 rpm and randomly missing. It gave a p0122 tps low volt and p0300 random misfire codes.

The p0300 and missing seems to be gone now but it's still idling fast.


In my grand prix I got a fast idle and a tps code once, I replaced the tps and all was normal so I tried that on the tahoe and no luck.

I've tested the +5v reference input, it's good. the voltage doesn't change if I unplug or replug the map or egr.

I've tested the tps ground, no resistance.

I've tested the tps signal wire from the tps connector end to the c3 or c4 pcm connector end, no resistance there either.

If I test the voltage in the signal wire with the tps connected I am getting between .45v and 4.75v closed to wot. (normal right?)

I am getting 14v out of the alternator.

I've cleaned most all the electrical connectors to sensors and components on the engine including the 4 big pcm connectors.

PCM should not have gotten wet in this stupid misadventure in dumbassery in a creek. it was the passenger side that went under in a big way.

So any other suggestions?

Could p0122 be a symptom rather than a problem? I mean like if the IAC was screwed up and letting in way too much air, would it give a p0122 since it's expecting the throttle to be open some at 2000rpm, but it's actually not and the IAC might be screwey?


A friend is going to bring a tech 2 over but it will be at least a week before he can. We're going to see if the pcm is seeing the same voltage as what I'm testing right at the signal wire where it connects to the tps. Also going to see if he can control the IAC with the tech 2 to see if it's maybe dead.
 

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Discussion Starter · #4 ·
not that I can tell. The alternator is making an awful noise so I took the belt off and ran the motor for a couple minutes and couldn't hear anything abnormal.

I blew some cigarette smoke at it while the belt was off and no fan to blow the smoke around, I couldn't see smoke being sucked in anywhere.

I would think with a vacuum leak big enough for 1500-2000rpm idle I'd hear it at least and probably see it suck the smoke.
 
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