engine shake help
could the fuel/air mixture be off when cold? pulling too much air since cold air is denser? no idea where i'm going with this theory...
The plugs should have been changed prior to me owning the car ish 18 months ago (probably 5000 miles)
I've run fuel injector cleaner a few times which seems to have helped but you have gone the full 9 yards. Yet to check the O2 sensor or the CSS but need to get some money together for a plug and lead change at some point. Goes perfect in every way otherwise. Found it surged once or twice when I was really really going for it (130mph ++ on a private airfield don't panic but it was very hot 32º c for the UK) but run 97+ RON Europe or Optimax 99 when I can get it. Driving me a little mad as well





Really frustrating and nobody seems to know what's going on, even star diagnostics. Star reports everything is running at optimal levels except for brief flashes of possible misfires when running smooth engine diagnostics.
Mechanic said possibly dirty fuel rail but not enough to trigger misfire codes. AMG engines are very sensitive and *****y. Hmmm, reminds me of certain species
.....but im sure everythings okay it doesnt bother me think i can live with it
i love my clk!!....good luck man
despite the issue, i still went ahead and modded the car with renntech air box and deleted my secondary cats/resonator...next in line are ams headers and tune to tie it together...
sounds good though i need mods on mine asap loll...goodluck with your monster!!
The Best of Mercedes & AMG
Let us know how you get on!!
but then again not everyone has these symptoms....i dont know lol
A full missfire is detected by the CPS circuit...if there is a fluctuation in RPM that is synchronized to a particular degree of rotation the CEL will mark the offending cylinder as a misfire. If you have RPM variation at random, then it will throw a 300 'random'. Unfortunately you have neither, so you are going to have to look between the lines. If you have a slight missfire with a bad injector then what I would look for is one of the banks to go rich/lean. This would indicate that the injector is stuck open, or stuck closed. I'd check to see if the readings that are coming off the O2's are the same as one another, and go with the one that is farther out of range. This will narrow it to the bank...if that bank matches #4, viola, it is the injector.
If you can't get it nailed down that way, then you might want to try to find one of those hard core electronic engine analyzer guys, the ones that can look at all of the sensor data and their relationships to come to a conclusion. Nothing gets by a guy that is really good at that.
Last edited by onlinealias; Aug 6, 2010 at 05:18 PM.
Not sure if replacing just about everything helped but the last straw was the crank position sensor. After couple of weeks of smooth idle in park, I replaced the cam position sensor and cylinder 4 coil pack. Didn't improve the idle but the rough idle also didn't come back.
Figure I would replace one coil pack a month just for maintanence.
Thanks for everyone's suggestions/advice. Great community we have here!







