Rough Idle at Start

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Jan 27, 2021 | 07:08 AM

shakinrock

Thread Starter

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Joined: Jun 2007

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From: Big Canoe Georgia

Rough Idle at Start

Folks, I started my car yesterday and immediately the engine at idle was unusually rough, nothing like I have ever experienced before. Here is the background. Two days before I washed my car and immediately put it back in the garage. Fast forward two mornings later and I had the rough idle. It is a Z51 if that matters. After I drove off it drove fine. I parked my car and restarted it several hours later and no issues.

So could water get somewhere after a hand wash that could cause a rough idle on the first start if the car sat for a while after the wash?

Jan 27, 2021 | 10:08 AM

Rabbi

Safety Car

Joined: Nov 2008

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From: Central Fl. Leesburg

I believe that these are electrical gremlins. Get used to it or it will drive you nuts

Jan 27, 2021 | 10:41 AM

MysteryMob

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Joined: Jul 2020

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It's entirely possible that you sprayed water and got it on something, then the heat of the engine caused it to evaporate and the problem was solved.

Jan 27, 2021 | 01:03 PM

dvilin

Team Owner

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From: Rochester, NY

^^^^^I agree with mysterymob.

Jan 27, 2021 | 01:29 PM

JMII

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Joined: Jul 2018

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From: Margate, FL

Could be a battery issue. If the battery isn't holding a charge then the problem might return if the car is started but not driven then sits again.

Unless you removed the hood vent duct a normal wash results in very little water in the engine compartment. Heck I've sprayed down my engine directly with water (low pressure of course) and it fires right up the next day with no issues

Jan 27, 2021 | 01:37 PM

Emmett

Racer

Joined: Apr 2003

Posts: 394

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From: Uniontown PA

I also had the rough idle issue happen last week.It went away after a few seconds but it did concern me at the time.

Emmett

Jan 27, 2021 | 02:03 PM

ersatz928

Melting Slicks

Joined: Mar 2001

Posts: 2,671

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From: New Jersey

Sometimes, if you cold-start an engine, and then only run it for a few seconds, and shut it off, the next time you cold-start it, it can have a spark miss due to fuel fouled plugs. The mixture enrichment from 2 cold-starts can sometimes temporarily foul a plug. I have experienced this problem with a few of my cars. Don't cold-start an engine and shut it off so quickly, let it run for 2 or 3 minutes.

Last edited by ersatz928; Jan 27, 2021 at 02:07 PM.