S500 misfire - any ideas please

[merc300e]

My S500 1996 148k FMSH has a misfire - garage tested it and said the voltage to no 3 cylinder was erratic but could not fix it. They tried changing the plug . No faults on fault code reader. Car throbs away on idle - fun but needs sorting - any ideas please or do I have to go to MB @ £90 per hour? Regards.

 

[angus falconer]

My S500 1996 148k FMSH has a misfire - garage tested it and said the voltage to no 3 cylinder was erratic but could not fix it. They tried changing the plug . No faults on fault code reader. Car throbs away on idle - fun but needs sorting - any ideas please or do I have to go to MB @ £90 per hour? Regards.

I had a similar problem with my last C43. I took it to BSG Mercedes who tested all 16 plugs, 16 leads and 8 coils. They found two faulty leads and one faulty coil pack. It's labour intensive but it's hard to see an alternative as the diagnostics don't go to this level of detail. So my suggestion is to take it to a specialist that you trust.

 

[jberks]

Absolutely. find a good indy. There are plenty around Mcr and £45 instead of £95 per hour so you can afford twice the labour! My misfires were always down to leads, but it needs a proper trial and error diagnoistic.
I can't understand how any self respecting engineer can hand anything back unfixed. I certainly can't. It becomes personal and reflects on my professionalism.

 

[merc300e]

Garage not fixing misfire

Hmmm - I thought I had taken it to a good MB special - 'The Garage' Whitworth Nr Rochdale - they seemed to have a good reputation but after several hours no fix. I assumed they were going to swap over coil packs etc until they found the iffy one - they do break MBs - but no. Still had to pay for several hours labour though. Now I have to pay again somewhere else. ( and then maybe somewhere else etc.) You really are in the hands of the technician - if you get a poor one who can not do the job you still pay. But that's life I suppose. I've had just as bad service from MB main dealers - eg. left the car with a fault - they phoned to tell me it had been fully tested on their fault code reader and the repair would be over £3000 - when I went back to the dealer the car had not moved from it's parking spot ( how can I be sure - I left a nut on top of the front tyre - it was still there ) The fault finally turned out to be a part out of alignment - they loosened 2 bolts moved the part tightened the nuts -fault fixed - ( 10 minutes ) ( I watched them do this ) still charged me £300 for the diagnostics. How do you find a good garage? Anyone know one in the Manchester area? Regards.

 

[jberks]

To quote myself earlier - I can't understand how they could hand it back. I make it very clear at the outset that I don't want a faulty car back so return it when its sorted - not before. I just don't get it.

I would be refusing to pay anything if they hadn't fixed it. Maybe a token £50 for having a look, but nothing more.
Its like an old mechanic friend who, when called out to a breakdown. Opened the bonnet, tapped something with a hammer and closed it again. Car fired up. "That'll be £50 please". When queried why £50 for 10 secs work he would replied £1 for hitting it, £49 for knowing where to hit it. (old tech's story I'm sure) The same is true in reverse. They can only justify several hundred pounds in charges if they have actually achieved something.

Perhaps I've been lucky - but I've never had the sort of hassle you had.
My suggestion would be to call the boss of the garage and explain that you are very unhappy having forked out so much money with absolutely nothing to show for it. He may do something for his reputation.

I can recommend the Leeds Indie if fancy a trip. (Merc Care) You could always give him a call and explain the story so far and ask him if he can help you. Just tell him you're as fussy as Mr Berks. If, after that, he's still willing to help, you're in with a chance!!
good luck and let us know how you go on.

 

[markku]

Wiring harness

My S500 1996 148k FMSH has a misfire - garage tested it and said the voltage to no 3 cylinder was erratic but could not fix it.

Please have the condition of your wiring harness checked. Some pictorial is available here: http://www.v12uberalles.com/projects_page.htm

 

[Parrot of Doom]

Greenvale in Whitefield seem quite good to me, and they don't take the mickey either. I've had a few jobs done there that I couldn't do myself, and the bills were very reasonable considering the length of time they had the car.

They also tested my ATF level and did an ECU diagnostic - completely separate, on another day, from the above jobs, didn't charge me anything for that.

Is it perhaps posisble to swap the coil pack for that cylinder with another working cylinder?

 

[Parrot of Doom]

Greenvale Services
Moss Lane Industrial Estate
Egremont Close
Whitefield
M45 8FH
Tel: 0161 796 2666

Good bunch, they're just around the corner from Whitefield Metrolink/Bus station.

 

[LNM]

Don't be so sure they didn't put the nut back....

Jokin

My father in law (ex father in law, but thats another story) had this 300CE in four dealers and four independents before the idle problem got fixed. ****** nightmare; it was on company expenses so not a direct financial hit, but it does indicate that MB dealers are quite willing to let people haemorage money for "diagnostics" that they clearly, and I mean clearly within the first five minutes, can't fix easily.

 

[merc300e]

Update - went to Greenvale - they put it on their computer and it showed no faults. Suggested I tried changing the plugs, did that today - no improvement. Do the injectors fail? Can you test them like I used to ( 30+ years ago) on my '73 TR6 - pull each out and squirt it into a jamjar to see the spray pattern - dangerous I know sqirting fuel about. Is it safe to take the plug off each injector in turn to see if one makes no change - or could this open circuit ruin the ECU? regards.

 

[dougtsc]

I know someone who prints some business cards on his home computer with his name on it and 'Trading Standards Officer' as his job title. He then leaves a couple 'on show' in the car before he takes it in to have some work done. Result is he always gets superb service and never gets ripped off !

 

[Parrot of Doom]

I don't know anything about the engine, but have you tried swapping the leads, or checking the dizzy cap?

 

[ALAN@ECUCLINIC]

As Seen In Another Thread If The Ecu Turns Out To Be Faulty(i Doubt It Coz It Normally Knocks Out 2 Cyls) Please Contact Me Via The Website Or Call Me 020 8761 7482