1989 L98 High Idle

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Mar 27, 2020 | 03:49 PM

Hammerhead69

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1989 L98 High Idle

I pressure washed the engine bay the other day after a drive (I let it cool down first). After I finished I cranked it up & pulled into the garage with no problem. Today (2 days later), I took it out for a drive & the engine idled high at 2,000 rpm at first & then about 1,200 to 1,400 after it warmed up. In drive it idles about 900 but when I put it in park it jumps back up to 12-1400. The “Service Engine Soon” light came on also. What have I screwed up? Maybe knocked a vacuum hose loose? It’s never done this. As the title says, it’s an ‘89 L98.

Mar 27, 2020 | 04:23 PM

CorvetteRules

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From: Mays Landing, NJ

I'd think first step would be to pull the code.

Mar 28, 2020 | 02:23 PM

Hammerhead69

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Solved it.
Checked the code (used the jump-wire method in the OBD port) & it was the TPS. Apparently they don’t like getting wet.

Mar 28, 2020 | 05:37 PM

CorvetteRules

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From: Mays Landing, NJ

Good to hear.

Mar 29, 2020 | 01:36 AM

aklim

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From: Hartford WI

Wonder why. I would think that they should be relatively water resistant.

Mar 29, 2020 | 04:11 PM

Hammerhead69

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Quote:

Originally Posted by aklim

Wonder why. I would think that they should be relatively water resistant.

Getting it wet is the only thing I can think of that fried it. It was running fine until I washed the engine. I’ve washed the engine before with no problems though.

Mar 29, 2020 | 08:14 PM

aklim

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From: Hartford WI

Quote:

Originally Posted by Hammerhead69

Getting it wet is the only thing I can think of that fried it. It was running fine until I washed the engine. I’ve washed the engine before with no problems though.

The plug has a rubber boot to keep water out so unless you are forcing water on it, something might have failed. After all, I have a nose hood scoop on my car and it gets driven in rain. That definitely splashes water on the throttle body