rizwan

Hi guys,

My 2000 ML430 one day got it's engine light on and started having a very rough idle, and especially when trying to go from a standstill. The car would almost hesitate to accelerate and then finally start moving.

The next day the car was a lot better (minor roughness in idle, no hesitation), I checked the codes at Autozone (gotta get me one of those readers!), and codes where for the EGR valve being blocked and Cyl. #4 misfire.

I cleared the codes, hoping that if it was a serious problem, the cel light would come back on. Well, it's been about 2 months now and the engine light is still off, however I still have a slightly rough idle.

Now, once you clear the codes, how long does it take before the car does that test again.

Also in case this newer (less) rough idle might be completely unrelated, anyone ahve an idea why? BTW the car's got 80k on the odometer, possibly time for new spark plugs?

thanks,
riz

springerfever

If plugs have never been changed, definately recommend putting in new ones. I went with the Bosch platinum 4's and have been very happy with them, but some swear by other brands. Just remember you need 16 of'em.

If you are handy with a wrench, its not a bad job...and you can save some money. Also, as long as you're in there, might as well remove and clean the EGR tube. On my wifes' 320 wagon, cleaning the tube and resetting the OBD did the trick........Good luck !

ML God

Your EGR Tube being block wont cause a rough idle. If you had a code for cylinder 4, more than likly the wires are bad. very common. it wont hurt to change the plugs either. very unlikly that the plugs are causing the rough idle. MBZ recommends plug replacement at 100K. I would be looking at replacing both of cylinder 4s wires
MLG