06KiaOptima idleshigh@40/wants to stall 20min. into driving

Fourth attempted fix failed. 2 times with “regular” mechanics, once with Kia dealership.
My 2006 Kia Optima will drive fine for about 20-30 minutes (last time 18 miles) I’ll hit a bump, stop, or turn a corner and then it acts up (engine light comes and goes). I have to drive with my foot on the gas at stops it wont come down from 40mph unless I break, It once wouldn’t go past 40 though and I thought it was going to stall out on me. Once shut off, It has trouble starting, but will start. Shut it off, it runs again fine for the next 10min or more. I have had the crank-shaft sensor replaced three times, (last by dealer for double the cost) New battery just put in a couple of months ago, spark plugs, the throttle body was cleaned, and threw in some high octane gas cleaner in the tank as well. Does anyone out there have any ideas? Every time I take it in, they say “it’s not acting up right now so we don’t know” …The only other issues that don’t seem too important right now are back sway bar and flex pipe. Would really appreciate some feed back. Thanks so much!

116,000 miles

Cam shaft sensor if applicable might be worth a replacement

High idle speed can be caused by incorrect coolant temperature. Have the thermostat function checked. A coolant temp sensor on the fritz can cause high idle speed too, but those rarely go bad. But if all else fails, worth a look anyway.

As far as the stalling and check engine light, have the diagnostic codes stored in the ECM memory read out and post them there.

If I’m reading your post correctly. The engine wants to stall out when you hit a bump. stop or, turn a corner.
I’m leaning on a broken motor mount and this stresses a electrical connector somewhere.
This could also twist the motor enough that a break in the air intake tube opens allowing too much air into the throttle body. This tube runs from the air cleaner to the throttle body and looks like a large shop vac hose…the ribbed type. In these ribs there can be a crack that opens up when the engine is twisted just right.


Thanks everyone for the feedback. My cars an hour away from me, but someone looked underneath and said he saw that my breaks are very bad in the rear. That it’s not even my sway bar bouncing around back there as I was told…anyway…They are thinking that the breaks somehow may be connected to the cruise control? Maybe a short there. I do think something is going on with the electrical system tho, my car locked on me last winter when I went to open the door. I’m going to talk to the dealer again this morning about this along with your posts. Very much appreciated, thank you all so much.

Bad brakes will not cause any engine problems.

This would be a good time for the OP to take a deep breath and have someone drive the car who can describe what really is happening. I am not sure if you can just look under the car and claim the rear brakes are bad.

There is indeed a relationship between the brakes and the cruise control. On the car’s I’ve rented with CC at least, if I pressed on the brakes when in cruise control mode, the cruise control kicks off. So there must be some connection between the two functions. But I doubt that is the issue here. Like posted above, when the CEL comes on, that means the car’s diagnostic software has detected a problem, and stored the details of what it discovered in its memory. You paid for that software when you purchased the car, so might as well use it. Suggest rather than guessing, have all the diagnostic codes stored in memory read out.