SL500 HT leads?

[blak500]

Hi guys i am having some problems with my 52 plate SL500, i bought it from Mercedes Benz of Wakefield as an approved car in 2006, 1 week later the pump controlling the central locking and the roof had to be changed under warranty, the automatic gearbox was changed, the car has recently had the drivers side ball joints and the hydraulic suspension unit changed (2600 pounds!) and the engine mountings changed last month as well, and now my garage is saying that the engine is miss firing due to faulty HT leads and it needs 16 new leads otherwise the cats on the car can be damaged? they only found out about the misfiring as they asked me if the car rides smoother since the suspension work, i said the same really, but the car in neutral still occassionally gives a small quiver, but it has always done this since i bought it from merc wakefield, and when i mentioned it to merc epsom and also AMC neither garages found any problems with the engine? can any of you guys shed some light on this as i am getting fed up of spending 100's of pounds on the car literally every 3 months since the warranty expired 2007!! thanks for your help!!

 

[gbjeppm]

As its out of warranty you need to find yourself a good independent, to get your costs down.

Whereabouts are you?

 

[skemball]

Typical main dealer stance to declare that all 16 leads need replacing. Sounds like lazy mechanic syndrome.

I would not accept that diagnosis at face value.

If one lead was occaisionally shorting/open circuit the affect on the engine at idle would be barely noticeable. If it is a noticeable 'twitch' its more likely to be on the low-tension side of the ignition affecting all 8 cylinders at the same time, or a fuel related problem.

 

[BlackC55]

There is not often much point in replacing one or two leads as the missfire can return on another lead within days.

You don't necessaily need genuine leads either. There are some cheap and nasty ones around and must be avoided.

A slight missfire on the 113(V8) and 112(V6) engines is a very common problem. 9/10 it is an ignition lead breaking down. I doubt it is a low tension issue.

 

[blak500]

hi guys thank you very much for posting replies, I will take to a good independent to get a second opinion, i am based in Epsom, surrey any good indys near me? Thanks!

 

[BaldGuy]

Hi blak, the best indie near you is BlackC55 at PCS, I know he is in Horndean and a small trip but he is used by allot of forum members (as do i for my 500) and is very highly recomended.. However Ollie is on hols from tomorrow for the Xmas period, so if you can wait until after Xmas, I would...

Cheers

 

[lynall]

I fitted new leads to mine complete set, dug out multimeter to test all old ones and 3 of the 16 had values over that marked on the plug caps, reading 3 ohms instead of the quoted 2 ohms
Also did the twitch thing at idle, now very smooth.



Lynall