Quote:
Originally Posted by glatt
I've got a car question.
Rough idle.
The car is old. After it warms up from driving around, when I stop at a light and push in the clutch, or shift out of gear, it goes into an idle where it's pretty rough. The CDs in the door pocket start to rattle against each other. The hard roof liner starts to vibrate against the roof. If I apply a little pressure to the accelerator and ever so slightly rev the engine, the vibrations and roughness go away. It does not have a rough idle when cold. (I understand the computer sends different signals to the engine when it is still cold than when it has warmed up and the fuel mixture is different then.) It is not rough when driving. This has been going on for a couple months.
How to improve? We had new spark plugs and wires (and presumably distributor cap?) replaced about 30K miles ago as part of a tune up done then, so they should still be good.
It has 115K miles now. We did that first (only) tune up at about 85K.
I could just go replacing stuff, but would like to know where a good place to start is. I was thinking fuel injectors. We've never done anything with those. Are clogged fuel injectors likely to cause symptoms only during idle?
Oh, this is a 1996 Geo Prizm LSI with the 1.6 liter engine and manual transmission. 115K miles. Starts fine. Drives fine. But idle is rough. Never stalls.
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Glatt, good news! That is a super easy fix.
Look to the right of the steering wheel for one of these. Twist the knob on the Left CLOCKWISE until the sound of the rough idling disappears. If you turn it all the way clockwise and you still hear the rough idle you may need to get a new one.