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are u sure urs is running spark plug wires, but not coil?

most of the MB i have worked on are running individual coil, in which no shop would replace all 6 or 8 of them for you unless they found it faulty.

i replaced all 6 on my friend's 328i because he has two dead in the last two months, everytime CEL came back and a diff cylinder is mis-firing; he is tired of all those ****ty driving performance and decided to replace the leftover 5 coils this time (the 2nd time)...

u have to know what code MB has found (should be on ur receipt), then from that code maybe i can see if they are missing anything else!?

what's the mileage of the car? even tho u have only put 4000km on it but it could be one with over 70k?! ML320/350/500?

my friend's S430, brought it back to MB and the car came out with a mis-firing code not long after; they changed this and that for him, paid over $2k and problem is not fixed; turned out when i checked thru his service history they have replaced 14 spark plugs on his V8 (which has 16)...as soon as we get rid of the last 2 spark plugs it's running like a beauty now...

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sky: were u saying dealer had all the spark plugs replaced? or do u mean the actual spark plug wire? cuz i think ML350 has individual coil?!?!

all spark plug wire replaced

anyways, ML350 with 70k, it's not a very high mileage that the dealer would have changed all the spark plugs for you (happened to a friend's CLK430, dealer took the plug out and "cleaned" them; threw them back in and CEL came back 2 ~ 3 months after, friend recalled they said the plugs were changed; i took them out regardlessly because of the S430 story, found out they were still the old one; my friend was about to drop by the dealership with his invoice, i found that they were not even replaced! it could be a mis-communication between my friend and the dealership, or the service advisor and the tech); double check the invoice and if they were only cleaned, give all the spark plugs a try?

also IMO your car has "unreasonablelly" low mileage for the previous year, spark plugs could have been fouled with unburnt fuel (even if they were just cleaned, better if they were replaced); have seen that happened onto a lot of the european cars, they really need a good warm up / heat cycle everytime u drive it; that's why european cars can take bosch spark plugs, but totally not recommanded on japanese...

also what's the actual code u are getting? Mis-fire? Multiple Mis-fire? a good way to find out if the coil is dead is to swap it with another cylinder, the check engine code will tell you so (more accurate than measuring the resistance)...

with such a low mileage car, moisture in gas tank could be another reason; you probably won't be able to finish up a tank in a month so if u leave the tank empty (low level) for too many days, moisture in the tank (regardless which gas station u go) will cause the car to run rough, hard to start; those can cause fouled spark plugs as well?

have u tried a diff gas station? like from chevron to petro can, or from petro can to chevron etc?

i just picked up my friend's corolla, 07, 2900km since end of last april; car was not driven for about a week but it was rarely driven even tho when his mom is around; as soon as an oil change is done and i finished up that tank (1/4 left when i picked it up), put in some chevron 92 and the car is totally diff (friend's mom was using 91 from shell)...she is so happy with the diff, and was surprised just a diff gas station would make such a change (she first thought oil change is not necessary, as toyota told her it's not due if it's not 8000km)...

all in all, servicing a vehicle involved a lot of infomation from how the owner uses it (such like my friend has a S2000 but that's his weekend car, he NEVER drives it during weekday and even it's a 06 with 12k, i can see moisture has already contaminated his oil; it's only his 2nd oil change ever since he bought his car lolz)...

i guess driving distance, warm up period, choice of gas, and many other things would affect how a mechanic works on your car; 03 with 70k is not decent average mileage, but the mechanic probably wouldn't know u only have 4000km since sept 06?

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原帖由 sky 於 2008-1-14 17:32 發表
Update:同舊車部經理傾過,我覺得佢好似見怪不怪,我見過worse過你都有,佢問我想点,我話而家俾你整你又整唔到,換過架俾我囉,佢話佢揸唔到主意,要寫report通知上頭,過兩日覆你啦!!最慶就係當我傻仔,佢話同我check過今次 ...

yeah try to get another one BUT i do agree if driving too little is not a good thing, especially if u dun warm up ur car before u drive; short trip can never make ur car warms up properly