Thread: Rough Idle on my Chevy 350

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You said it's only been driven 400 miles in 5 years, right? How much have you driven it since you bought it? Before I did anything in the troubleshooting arena, and for sure before I started changing parts or buying things I'd change the oil, change the coolant unless you know it to be fresh, check the tranny fluid for color and sniff test and if OK (clean red, no burned smell) I'd take it out and drive it. Once it's warmed up to operating temperature run it up in rpm several times and see what you get. If you get any backtalk from it then head to the interstate (or similar open road) and run it above 3000 rpm for at least twenty minutes if you can do that without getting too far over the speed limit. That will clean off the plugs of any deposits, and might smooth things out for you. When you get back pull a few plugs and read the color - you can find a chart by Googling "spark plug color", and see if that tells you anything.

Not to worry you, but having the car sit that long likely means that it's had the same gasoline in it for a loooooong time, and that can be bad with todays ethanol blends. You might have eaten up anything rubber in the fuel system, but do the drive first, then worry about problems once you've got some real time info.

Good luck with the shakedown!! Oh, and just to clarify, 'high test' only burns slower than "regular" to eliminate detonation in higher compression engines. If your engine runs knock free on regular then you'll get less power and efficiency with higher octane fuels.

Originally Posted by rspears

You said it's only been driven 400 miles in 5 years, right? How much have you driven it since you bought it? Before I did anything in the troubleshooting arena, and for sure before I started changing parts or buying things I'd change the oil, change the coolant unless you know it to be fresh, check the tranny fluid for color and sniff test and if OK (clean red, no burned smell) I'd take it out and drive it. Once it's warmed up to operating temperature run it up in rpm several times and see what you get. If you get any backtalk from it then head to the interstate (or similar open road) and run it above 3000 rpm for at least twenty minutes if you can do that without getting too far over the speed limit. That will clean off the plugs of any deposits, and might smooth things out for you. When you get back pull a few plugs and read the color - you can find a chart by Googling "spark plug color", and see if that tells you anything.

Not to worry you, but having the car sit that long likely means that it's had the same gasoline in it for a loooooong time, and that can be bad with todays ethanol blends. You might have eaten up anything rubber in the fuel system, but do the drive first, then worry about problems once you've got some real time info.

Good luck with the shakedown!! Oh, and just to clarify, 'high test' only burns slower than "regular" to eliminate detonation in higher compression engines. If your engine runs knock free on regular then you'll get less power and efficiency with higher octane fuels.

So I took her out and ran her pretty hard on the highway. When I got home and put her in the garage....no more dieseling!!!! Thanks everyone!