Q: My car is idling very rough.

asked by on December 22, 2016

Yesterday night my car started idling very rough, so I figured out shortly after that I had little to no oil in the car (my oil indicator doesn't work), and so I filled the car with oil, and thought that would fix the problem because before the only thing that was wrong with my idle before was the idle air control valve which I fixed shortly after getting the car, so after I filled the car with oil then I drove for about 10 minutes and the car was smooth for the first 2 minutes then it would idle very rough at stop lights and stop signs but around 2-3k rpms it would drive smoothly, and I was wondering if it just needed some more time and it would settle or is the problem deeper than the oil. I have never really had any issues idle wise other than the idle control valve, I am in need of some help so thanks in advance.

My car has 187000 miles.
My car has an automatic transmission.

The idle air control valve is common for causing a rough idle in many cars, but it sounds like you have already corrected that. Another thing you may also want to check is the crankshaft position sensor. A crankshaft position sensor monitors the position or rotational speed of the crankshaft. This information is used by engine management systems to control the fuel injection or the ignition system timing and other engine parameters. When this is faulty or not working properly, this will cause problems with the ignition system and generating spark transmission to the spark plugs resulting in starting problems, rough idling and other performance issues. You may also want to check the fuel pressure as low fuel pressure can also cause rough or poor idling if the fuel pattern being sprayed from the injectors is not consistent. This can also happen in the case of having dirty fuel injectors which may also interrupt the spray pattern of the injectors. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your car.

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