rough idle
04-23-2007, 01:41 PM
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rough idle
hI CAN SOME ONE PLEASE HELP have just purchased a merc clk 320 (208) 35,000 on the clock . however when stationary for a while i noticed the idle becomes rough.i my obvious cure was to change the spark plugs..but i didn't work. now my mechanic suggests changing the coil pack and leads..any better suggestions please
04-23-2007, 03:33 PM
#2
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If all that's wrong is the idle, that's typically the motor mounts. These cars have fluid filled mounts that leak when they've grown old. Also, your car has six coil packs. The odds on ALL of them needing replacement are minuscule. If a "single" coil pack was bad (not firing) that could be determined with a timing light. If a single coil pack was not firing under load, or misfiring under load, that can be determined by putting a sniffer in the exhaust and measuring the HC levels. In any of these dead coil scenarios, the CE light would be burning a hole in the dash. The ECU knows when the coils fire, and when they don't.
04-23-2007, 10:06 PM
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doubt if its maf at 35k but then motor mounts to go out that early is weird as well, if u change the motor mounts change the transmission mount as well especially if its smooth when u shift to neutral...to check if the motor mounts are bad hold the brake down and slowly rev ur engine if there is any movement in the engine, its ur engine mounts...
04-24-2007, 02:45 PM
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2001 clk320
I had my MAF changed around that mileage, for similar problem but it turned out to crankshaft sensor. Once the mechanic replaced and updated the wiring the problem was gone.
04-25-2007, 07:55 AM
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problem solved
Thanks to all those who replied to my post..all comments well appreciated However after spending the better half of the morning with my mechanic, i got him to hook the car onto a diagnostic computer to test all the individual valves we found out that valve no 3 was the main problem he changed the two spark plug leads ...now the car drives like a dream it cost me £50 in total
£16 each for both leads and £18 for the use of the computer think i got a result there....keep on posting!!!!!!!
£16 each for both leads and £18 for the use of the computer think i got a result there....keep on posting!!!!!!!
