E320 (W124) misfire

[Williamwoo]

Hi all,

Having just bought a tatty but reasonable mileage (114k) 1995 E320, I have a question that I would appreciate some advice on:

I have an occasional misfire. It feels very much like it is not firing on one cylinder, and most often happens after slowing down to and then accelerating from walking speed. At high revs, I don't get the problem but conversely it won't rev much beyond 4000 rpm when at a standstill (it sort of coughs and splutters at 4300 and then drops back to 4000 cyclically). I'm not averse to getting my hands dirty but I simply haven't had time yet to look myself, but a mechanic friend of mine says the coil packs(?) are all fine and there is no arcing from the leads. There's no oil in the water or vice versa and when it's not misfiring it's as smooth as silk. He's suggested replacing the spark plugs next - does this make sense? Any thoughts gratefully received.

Many thanks.

 

[BlackC55]

Check the engine wiring loom. They break up and is a well known issue

 

[d w124]

Hi and welcome to the forum.As ^ it might be the loom and is a known problem on W124s but is still worth checking the coils.As for the rev`s,that`s normal

 

[abecketts]

welcome to the forum though it does sound like the loom, budget £550 for the loom plus 3 or 4 hours labour or at least that's what our indy suggested for labour.

 

[grober]

welcome to the forum though it does sound like the loom, budget £550 for the loom plus 3 or 4 hours labour or at least that's what our indy suggested for labour.

Its a pretty easy DIY. You just lay the new loom on top of the old one and methodically substitute the new for old at all the connectors. Here's how to do it. PeachPartsWiki: W124 Engine Wiring Harness Replacement the DIY writer estimates 20minutes to remove old loom 20mins to put in the new one!!

 

[kth286]

Williamwoo

where you based ?

there is an informal meet in south London this Sunday - if you come along we can read the fault codes and it will tell you which cylinder the fault lies, and we can then investigate from there.

see events/meets section of the forum for meet details/venue etc

 

[Williamwoo]

Hi all,

Many thanks for your responses. I've now read up about the wiring loom problems and checked the various easily-accessible wires on the front of the engine, and a couple of others and they're in poor shape so I guess I'll need to replace the loom at some point (£500+... blimey). However, in the meantime, I replaced the spark plugs and, for the time being at least, she's running beautifully!

I live near Weston Super Mare so unfortunately a south London meet is out of the question this time. Can anyone recommend any specialists in the north Somerset area for future reference?

Many thanks

 

[mejermy]

W124 degrading loom

Adding to the OP's query; can anyone imagine that the cars which have along and higher mileage FMBSH haven't had the loom changed? I have read elsewhere that many techies won't touch these for engine work (even plugs) if the loom hasn't been done. Surely this attitude would have prvailed by the early 2000s in the franchisees, esp where higher mileage cars, such as mine, were concerned.

What does the team think?

 

[BlackC55]

In the early 2000's the loom problem was not such an issue.