Hey guys

I've a check engine light on last night after a long run

The car runs fine and still pulling strong. However on idle the car shakes quite a bit, especially after long highway driving. The rpm stays steady on 1000 at idle but you just feel the car keep shaking.

I also notice the shaking occurs after I changed to Mobil 1.. Shouldn't the engine supposed to idle more smoothly after changing to synthetics?

I wonder would it be the dreadful #4 cylinder problem? What are other symptoms of misfiring?

Please advised.

Alex

 

btw i already checked my gas cap
it's still on

 

When the check engine light is on, the ECU is running on a pre-programmed fuel map that ignores the various sensors. This alone can cause a rough idle. This doesn't usually affect hard acceleration because wide open throttle (WOT) ignores the sensors also. Get it checked out soon! It could be all sorts of things.