Sl500 Misfire Help Please

[Eugene Hughes]

I have an R129 sl500 2001. The car has developed what seems to be a misfire, mainly noticeable on idle. I have also noticed that recently the gearchange is not so smooth. and kind of ghosts a little, if that makes any sense to anyone but me! Anyhow. I took the car to M/B today, and they ran a diagnostic test on both problems. Sadly, nothing showed up. Gearbox oils at correct level. The engineer said that the 'not so smooth gearchange could be caused by the engine misfire, and he expected it to be leads or plugs required. Well I had new plugs just 2,000 miles ago, so i guess that leaves leads. They quoted me just under £400 for the leads plus fitting. I can't afford that nowadays, especially if it turns out to be something else causing the problem. Any help from the forum guys would be greatly appreciated . Ps I am in Kent.

 

[television]

Dissy caps and rotor arm are a big reason, condensation in the dissy cap is another problem

 

[Eugene Hughes]

Thanks Malcolm. I am a bit of an egg with these things. How should I go about this. ie. in what order. Is it a case of wiping the inside of the cap like I used to on my old ford cortina, or is it much more involved?

 

[television]

Thanks Malcolm. I am a bit of an egg with these things. How should I go about this. ie. in what order. Is it a case of wiping the inside of the cap like I used to on my old ford cortina, or is it much more involved?

Start by doing that, also check the rotor arm and cap for any tracking marks, some of the sprays such as PTFE and silicon work quite well

 

[Eugene Hughes]

Thanks Malcolm I will endeavor to get into the cap. Are they still held by 2 clips. Easy to get open I am hoping.......?

 

[television]

Thanks Malcolm I will endeavor to get into the cap. Are they still held by 2 clips. Easy to get open I am hoping.......?

They may have those funny headed screws, but they do come off easily

 

[jberks]

will a 2001 500 have dizzys? I thought they'd all be modules.
plug leads sound about right, especially if they've been disturbed recently with new plugs, although it is worth checking they've been re-installed correctly - they can be hard to reattach to the plugs and if one isn't on right ...
also check inside the supressor caps - 2 of mine were corroded.

My indie fitted a set of leads to try - it worked in my case so I kep them on, but if it hadn't there were willing to swap then back out. Dealers won't do this but a good MB specialist may do.

I'm not convinced with genuine MB leads. I paid £250 for a set for my 240 and 3 years later, the misfire returned (cured by another set). So, it may be worth trying a decent after market set which should be a similar quality but a whole lot cheaper.

 

[television]

JBerks you are 100% correct, I got the year completely wrong.

Sorry Eugene:Oops::Oops::Oops::Oops:

 

[Eugene Hughes]

Changed plugs and leads today. Still damn lumpy idle. I did notice though, when checking the leads. On two of the plugs there was a yellowish spark, but the spark was the usual blue on the other 14. Does that suggest anything in particular?

 

[television]

Changed plugs and leads today. Still damn lumpy idle. I did notice though, when checking the leads. On two of the plugs there was a yellowish spark, but the spark was the usual blue on the other 14. Does that suggest anything in particular?

Coil pack possibly there is not much else, they are a problem on the 320 but not so much on the 500

See what BlackC55 thinks

 

[jibcl500]

On your SL500 there will be a coil pack for each plug, eight in total, swap the plug that fires a yellow spark with another plug and see if that is yellow, if so swap the coil pack for another and test again.

jib

 

[Eugene Hughes]

There are 16 plugs. Does that mean 16 coil packs

 

[television]

There are 16 plugs. Does that mean 16 coil packs

No sir,only 8 1 per cylinder

 

[Eugene Hughes]

are they very difficult to remove these coil packs?

 

[television]

http://www.detali.ru/cat/oem_mb2.as...GA=722.624&CT=M&cat=07N&SID=15&SGR=060&SGN=03


Here is one

 

[Eugene Hughes]

Just to let you guys be aware. I phoned MB for a quote for a new coil pack. They quoted me £120 +vat. The exact part from Bosch is quoted at £40 + vat!

 

[Eugene Hughes]

Sorry typo. It should read £49 + vat

 

[jibcl500]

Result, when do you get the part.

jib

 

[Eugene Hughes]

This afternoon

 

[Eugene Hughes]

Thanks for your expert knowledge Giles. I will arrange a day to come up to see you later today. Thanks mate