Car sometimes has a very high idle and it will accelerate on its own

5

Asked by T8ertot1989 Nov 27, 2018 at 08:19 PM about the 2002 Mitsubishi Eclipse GS

Question type: Maintenance & Repair

Car sometimes has a very high idle (3k rpm) and it will accelerate on its own
in 1st gear- much more so than is normal for an automatic transmission. I
checked for vacuum leaks using the carb cleaner method. I was unable to
detect any leaks. I also attempted to clean the throttle assembly as I thought
that it might not be closing all the way.

Even though there was no Check Engine Light on, I decided to connect an
OBD ii device and got the codes P0135, P0421, and P0443. I know that the
first is about an O2 sensor, the second is something about a "warm up
catalyst efficiency" and the third is regarding the EVAP canister.

What do you all think is going on here?

2 Answers

7,605

Perhaps the air idle control valve is sticking causing excessive air flow. Would do another smoke test, clear the codes and see what comes back there. Hopefully there is no issue with the evap canister. Some people top off the tank and have issues there. Would still check all those lines in the rear as well.. Good Luck!

1 people found this helpful.
5

Any advice on how to make sure that valve doesn't stick? Also, how would I investigate the evap canister? Unsure about the historical gas-filling behavior of the driver of this car (my fiancee). Not sure if she tops it off or not.

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