Hey guys,

Just recently my car seems to be "dieseling" when I shut it off. I daily drive it to school (about 15mi) and around town, but it seems to do it mostly after it's gotten warm enough. Typically the drive to school will do it. However, it's not consistent. I stopped for gas half way to school today and it dieseled REALLY bad at the gas station, but shut off fine when I got to school. Any idea what I should look into for causes?

Thanks!

 

If you have an idle stop solenoid, make sure it's functioning correctly. What is your idle RPM?

 

Unsure, unfortunately I don't have a tach yet.

 

Your engine may have carbon buildup causing hot spots thats igniting the left over fuel. You may be using to low of an octane level fuel. It can also be caused by too high of an idle setting. Among other issues.

 

This is interesting, because I recently went back to using 89 octane instead of 93. My engine is basically stock, but it seemed like it ran better on 93 (even though there's no real reason to that I knew of). Maybe it wasn't placebo? I'll try going back to 93 or using a booster on this tank I just filled.

 

To stop the dieseling until you can identify and correct the problem, leave the car in Drive (or Reverse) when turning the ignition off, then put it in Park and remove the key. The extra drag on the engine by leaving the car in gear is often enough to stop the dieseling.

 

Agreed, shut it down in gear, it should help with the dieseling until you get it straightened out. Also, use premium, dieseling can be very detrimental to an engine. It is detonating, and could be while driving too, but you can't notice it. If that's the case, it can do some serious damage. 93 octane is cheap insurance.