Missfiring 500SL R129

[KNU7S]

Just been out and about most the day in the SL on the way home from Birmingham, i noticed it was a little lumpy on acceleration.

after a while it did seem OK then it came back??? I had to replace a distributer cap a month or so ago, should i of replaced the together?

whats the best way of telling which cylinder is not firing?

Thanks in advance

 

[MangoMan]

Pull one plug lead off at a time until you can't hear any difference...that'll be the one.

 

[KNU7S]

I will try that, should i do it when the engines running? wont i get a shock?

 

[GregE240]

Just been out and about most the day in the SL on the way home from Birmingham, i noticed it was a little lumpy on acceleration.

after a while it did seem OK then it came back??? I had to replace a distributer cap a month or so ago, should i of replaced the together?

whats the best way of telling which cylinder is not firing?

Thanks in advance

KNU7S,

No advice (sorry), but I'd love to know what the problem is as mine occasionally does this. Seems to go after a short while too?

My dissy caps were (allegedly) replaced last year. Not touched the engine since it was serviced back in April this year.

Rgds
Greg

 

[stats007]

Voltage tracking with hairline cracks in distributor caps on these is a big problem. Normally the first thing to check then the plug and leads, follwed by injectors.

 

[KNU7S]

Greg

I sometime got a little misfire when the car had been sat a while but i was told this was just a little damp (common problem so i am told) this would soon clear once the engine had got warm.

I am going to spend a bit of time on it at the weekend and get it sorted as i want to sell the car soon and i want it to be right for the next owners

Tim
KNU7S

 

[MangoMan]

I will try that, should i do it when the engines running? wont i get a shock?

The way I usually do is to first remove the plug leads from the plug and then rest them on the plug, but not push them on, this makes it easier to remove for testing. I also use quite a heavily insulated pair of pliers to remove the plug lead away from the plug while the engine is running. When you remove one either the engine will misfire worse, or if it doesn't then that will be the plug that is not firing, or the lead faulty.

Hope this helps.

Cheers, Bill.

 

[Vlad]

As I understood it there is a Mod you can fit to stop the condensation building up in the Dizzy Caps.

 

[KNU7S]

Last weekend i run the car for 5mins, then removed all 8 plugs, one was soaking in petrol, swapped all the pugs around and ran again for another 5 mins, the same cylinder had a wet plug.

I inspected the distributer cap and rotor arm, and they do look pretty grotty!, so hopefully some new ones will make all the difference!

 

[GregE240]

Just an update on my situation:

On Saturday I took my car to an MB specialist in Milton Keynes, who looked at the caps and rotors. This in spite of having new caps and rotors last year.

Not happy. Seems I paid for Bosch and thats not what I got....some other brand dizzy cap was fitted, and it looks as if the original rotors are still fitted.

Both caps are shot and the rotors are knackered too.

Not impressed as it *should* have had new Bosch caps and rotors last year. Well, thats what I paid for.....

 

[KNU7S]

Do you still have the receipt for the work done?

Mine is still sat there waiting for me to order another cap and rotor!, had to tidy the garage!

 

[GregE240]

Do you still have the receipt for the work done?

Mine is still sat there waiting for me to order another cap and rotor!, had to tidy the garage!

Receipt? I can't be bothered. I just won't be using that garage again. To be honest it wasn't the first time they screwed up, so even more reason not to go back.

Don't want to say too much more online. PM if you want more info.

 

[rajinder_1]

Greg,
How are you mate, who was it that you used? is it the garage i think it is?

Raj

 

[GregE240]

Greg,
How are you mate, who was it that you used? is it the garage i think it is?

Raj

Good thanks Raji.....sent you a PM.

ATB,
Greg