I'm stumped, Grand Am reving up when put in gear.

[91z24build]

Can someone please help, Its got me stumped.

Ok here's what happened. The car was drove in about 18" of water almost 2 months ago. It drank enough to water-lock the engine (water on pistons). So I pulled all the plugs, cranked the water out of the cylinders, changed the oil, and got it home. Changed the oil again, and thought all was good. The next day it started to idle at 2300rpm after about a 25 mile trip. After that while trying to figure the idle out it blew the coolant tank, checked engine temp with code reader and it was at 220 degrees. Tore the heads off got all new gaskets and replaced the heads.

Got it all back together, and all was good, it was still idleing a little high about 900rpm, but wasn't getting hot anymore. Everything seemed to be working properly until I started to test drive it. Pulled it down in drive and all the sudden it started reving up to about 1500rpm in gear, and when I put it back in park it was ideling at 2k.

Now you can start it and it idles at 900rpm then when you put it in gear it starts reving up. The only thing you can do at this point to make it idle back down is cut it off and start it back, then it will do it all again.

I am completely lost on this one, I thought it might be the IAC but replaced it and it still does it just not as crazily.

[86FieroSEv6]

Sounds like a corroded connector somewhere. Does your scanner show TPS etc.?

[prophiseer]

If it sucked water up - I'd be looking at intake sensory inputs. More than likely a goofed MAF, TPS or IAC. Possibly something as simple as the throttle plate being extremelly gummed up (between built up carbon + water).

[91z24build]

The scanner was a friends, so I couldn't tell you...

I did just test drive it after unplugging the IAC and it shifts like you're flooring it the whole time, I'm starting to think TPS also.

Thanks, any other idea's/suggestions will be appreciated.

[91z24build]

Well guys that was it, the TPS. Its perfectly fine now.

I couldn't believe it... the tps of all things make it do that crazy stuff.

[pocket-rocket]

Sounds like a corroded connector somewhere. Does your scanner show TPS etc.?

I still wouldn't blow this response off. I remember a segment on a show (might have been 60 minutes) where people were bringing cars up from Florida that had been involved in floods from hurricanes and stuff and would completely clean it up inside and out and sell it at a really nice profit since it was a Southern car. Well, many people died in these cars becaues of connectors corroding and causing fires. I would go through the harness pulling connectors and slap them with some dielectric grease to make sure corrosion won't be a friend of yours down the road, or your car could develope some strange and hard to track down problems, or worse, catch on fire.

[60dgrzbelow0]

FWIW... One other issue that is worth keeping in mind and investigating is the position of the throttle body cable assembly and whether or not a broken motor mount would allow the engine when at higher RPMS to torque the motor out of position inside the engine compartment and make the cables tighten up enough to pull the TB into a WOT condition and leave you with a runaway vehicle on your hands.