W124 260E - sounds like missing at low revs, when warm

[mattwrigg]

It fired up this morning ok (after about 5-6 secs turning over) and idled smoothly. However, after 5 mins of driving the old problem appeared of juddering/missing at low revs. Even if I put it into neutral, the problem is still there, it will rev to high revs, but still hunts a bit at idle and stalls sometimes. Putting it into drive results in a stall, as the car is trying to drive at low revs where the problem is, and no power, hence the stall.

When my brother started towing me though, we thought that trying to keep the engine running will help with the brakes/steering, when I fired it up again the problem disappeared, it ran smooth as silk!

What can my problem be? Ignition? Fuel? (i had a new fuel pump fitted a few weeks ago, and as it will rev high don't see how it could be fuel)

It's weird how the problem only appeared as the engine warmed up.

Can somebody give me some pointers before I ask a garage to have a look?

thanks
Matt

 

[Joe260e]

Hello,

I have this exact same problem; did you find out what was causing it? Or does anyone else know what may cause it?

So far I have changed the plugs, checked the plug lead contacts and cleaned distributor. I am currently trying to clean the injectors with Redex. No improvement so far (50 miles). Any advice would be very much appreciated.

Cheers,

Joe

 

[Terminator]

Just a thought, but did you change the air filter?

What make of spark plug are you using? My manual lists Beru or Bosch but the former have been problematic so I have changed to NGK which are much better imo.

 

[Joe260e]

No I haven?t changed the air filter but I took it out and it looks clean. I thought for it to cause a problem it would have to be quite dirty. Is that true?

The plugs that are in are NGK copper core. On inspection one is a little blackened on the white ceramic part. I'm told this suggests that cylinder is miss firing intermittently. In response I replaced the ignition leads, which seems to have helped a little but there is still some miss firing when I rev from idle.

I'm going to give it a few days and see how significant the improvement is. It's unnerving (and dangerous) to lose power when pulling out on a busy roundabout.

Apologies if I have hijacked this thread. :-D

 

[pascal]

Joe,

Don't know what car youhave, but presume its a 260E W124

Check OVP relay if you have one. In box behind battery. Poor conections around it fuse etc

If the Redex didn't work (sometimes takes the full tank to work) (worked for me when my 300CE was cutting out sporadicly going into roundabouts etc)

After that, I'd go back to the Distributer. (replace?)

 

[Joe260e]

Hi, It is a 260E W124. I have been away for a couple of days so it has had a good run. I have done over 300 miles now with Redex in. When I arrived on Saturday after about 60 miles on the Motorway it seemed worse than ever. I wondered if the rain has anything to do with it. I'm going to have a look at the OVP relay today.

Incidentally, what should the EZL fuel selector thing be set to?

 

[Daniel T]

Joe, I had this low revs stalling and hunting fault when I first had my'86 W124 260E. The Air mass intake under the throttle body had split, affecting the fuel/ Air mix - replacement and a retune solved it.

Daniel

 

[turnipsock]

It may be a vacuum problem...does the perfomance gauge work correctly? It may be that there is a loose pipe somewhere and once the revs get up there is enough of a vacuum to suck the thing on.

 

[Joe260e]

Thanks for the replies, firstly Is there an easy way to check for vacuum leaks? or should I take off the air cleaner/filter and have a look.

Also where is the performance guage? if it has one. There's coolant temperature, petrol and revs on the dash.

 

[pascal]

Incidentally, what should the EZL fuel selector thing be set to?

The EZL - ECE (not Cat) or EZL - KAT (with Cat) should be set at 'S' for normal running on 95 Ron or higher grade fuel fuel.

The 'N' setting is for use with regular fuel (91ron to 94ron) and should only be used for temperary periods (in the case of when 95ron is unavailable)

PS I missed your question earlier on the 12th


Pascal

 

[turnipsock]

both my cars have a gauge that goes into the red when I accelerate hard. It's at the bottom of one of the big dials. It's called a performance gauge, but it's really just connected to the inlet manifold. If it isn't going through the full range then there is a leak somewhere.

The dealership will have some device for checking the vacuum. It wouldn't be much good if the fault is intermitant though...it's bound to work fine when yo take it in.