Misfire Diags..The saga continues..

[Merc600sec]

This is making LoTR look like a short story but.
EVENTUALY I relented and booked my beast into a dealers for diagnostics and to have them reset the adaptive ignition system modules.. My local stealer would not touch it .. so had to go 15 miles to another.. who gets lots of work from (*****) interesting that.. will let you all know how things progress..

[Merc600sec]

WTF..get a phone call from Merc Teky Bloke saying they have done the diags.. and that the problem is I appear to have a airleak somwhere in my inlet-manifold. This is causing to much air to get into the system and causing the misfire..Oh yes and the price to fix will be £2,500 ($4500)+ to correct it.. as this requires a partial engine out situation..I am IMPRESSED.. but not yet convinced..I would have thought that to much air would have meant the AIS wouldhave made the mix richer.. but mine is running weak.. both sides..I didnt get the diag printout but will try and get my hands on it and see if I can make any sense of it..

[mercS600]

Exactly what my friend had wrong with his '99' T reg BMW 520!Only difference is :-1 x new gasket supplied and fitted and 2 x Lambda sensors =£680.And thats at the BMW main stealers!MB have a lot to learn over pricing realistically and customer satisfaction!Re my own faults - well it's in the main stealers next week for 7 days+ to try and iron everything out!Fingers Crossed ££££Kerrrrrchinnnnng![xx(]

[barry putnam]

[:)]
I am happy for you that they seem to have located the fault. Sad at the cost however.

[pcmaher]

I thought your problem sounded like a vacuum leak, or more precisely, an intake leak. On older american engines, I used to take a can of gumout (carb cleaner), and spray at the interface between intake manifold and heads with the car idling. If RPM's increased, that was a sure sign that there was a leak in that area. Is this a technique that could be used in your case? I imagine one would have to use an O2 sensor safe cleaner. Who knows, maybe the problem isn't as bad as it seems?

[Merc600sec]

Does ANYONE have a diag of the VAC tubes at the rear of a V12 engine ??? What is taken off where.. and what goes where.. and the vac for the gearbox valve system ??

[pcmaher]

Hope this helps...

[Merc600sec]

Thats really good that is THANKS .. pcmaher send me your addy will send you a prezzy..

Anyway- still not convinced about the Inlet manifold leak.. so I am going to make two cover plates for each side of the inlet manifold .. attatch a vac pump to one side and then listen and watch to see if the guage drops..
It's my thinking that then I will be able to find out if it is a tube off or leaking.. wihout all the noise of the engine
I just cant belive the MB Tecky telling me its a "common"problem with these engines, anyone of my other V12 COMMON friends experienced this .. please respond..

if it is indeed a gasket Which I doubt then perhaps some high modulus sealant might do the trick??under vacum to pull it into the hole what do you think???

[guydewdney]

an old trick used on bikes to find inlet manifold leaks is to spray WD40 or similar (using the tube thing) onto bits where leaks may be - if the revs go up or down with each squirt thats where theres a leak...

worth a try for 3 quid?

[pcmaher]

I'm not following your plan Merc600sec. Explain slowly for me.[8)]