Another misfire thread W124 M111 2.2

[Robbarr88]

Hi everyone.

I have a 1994 W124 and iv recently fitted a new loom, the car hasn't been ran in about 6 months so came to fire it up and its started but running very lumpy.

Whilst the car was in storage, it had been parked in a terrible place which has leaked water into the top of port 3 & 4 i removed the HT leads cleaned and dried them and replaced the plugs.

However still lumpy, i suspect there may be moisture trapped in the HT leads and have ordered some new ones to replace.

Im a bit out of touch with the old mercedes, so could damp in the HT leads cause the misfire? Im starting with this before going down the coil route etc, i know the loom is good as its brand new along with the coil lead.

Thanks in advance.

 

[Dodipops]

Yeah damp in the leads would cause a misfire.
Start at the basics first but yours might have the ignition amplifier on the wing somewhere

 

[Robbarr88]

Thanks dodipops, i dont think it does have the amplifier but it check the basics hopefully something simple, thanks again

 

[optimusprime]

Rob go through all the electrics under the bonnet .Clean the contacts up . I would check all the fuses and fuse holders that the fuses fit in to . Only miss i ever had on the ht side , was one of the ht lead .On my W123 and the W124 both had the same problem .So untill you have your new ht leads dont work on anything else till you have fitted them, and then see what the results are .

 

[Robbarr88]

Thanks optimusprime, so iv replaced HT leads no joy.

But its idleing on and off, so sometimes it will sometimes wont, what we did notice is the CAT is ridiculously hot even after 10 mins of idle? We've checked all the leads, coils etc and now starting to think it could possibly be a sensor, thats causing the issue.

Anyone have any idea? Misfire, catalytic converter hot and smells fuelly on and off and also every now and then it almost sounds like theres a pop from within the engine? The engine ran fine before so can't be a timing issue etc, any help is much appreciated.

 

[Dodipops]

Maybe the cat is blocked? Try disconnecting before cat and see how it runs.

Obviously over fuelling would cause the cat to heat up as well, like maybe an injector pouring in instead of spraying.

 

[optimusprime]

Robbar what plugs did you fit ? Also unburnt fuel going into the cat will damage it . Might be hard to do but as Didipops said,, remove silencer before the cat . Or remove the nuts on exahusr manifold and pull the manifold away a little .

 

[grober]

The lambda sensor lead from its location on the exhaust manifold is usually clipped to the side of the cylinder head cam cover before reaching a connection on the bulkhead-its a prime candidate for thermal degradation and is not part of the loom per se [ comes with the part] Have you got the correct plugs----take them out and check the tips individually visually for signs of overheating, over fueling, misfiring

 

[Robbarr88]

Thanks for all the advice guys, ordered some new plugs to make sure there correct (they've been in since i bought the car) and il check the cat and lambna sensor as well ....Thanks again

 

[grober]

get ngk plugs BCP6E

NGK Partfinder for Cars & Light Commercial Vehicles

note - should be non resistor plugs = no R in the code

 

[Robbarr88]

Cheers grober! Just ordered them

 

[Robbarr88]

Update 18.07.2020 - So fitted new plugs, HT leads, removed exhaust and checked CAT for obstructions, changed fuel filter,....and still not running right, the car now idles roughly but every now and then theres a pop within the inlet manifold.

The car has now done 195k so im starting to think a combination of the mileage and it been stood for 6 months the cylinder head may have stuck or carboned up valves, causing the pop within the inlet manifold with it not seating properly.

The cars had just about everything on the ignition and fuel side replaced so i know theres no faults there, so starting to think it been stood so long is a factor, as it ran great before the loom disintergrated.

The next step is to remove the head and have it reconditioned but was really wanting to avoid it, if anyone has any advice on first hand experience or advice would be greatly appreciated.

 

[grober]

Your next step should be to get the car on an exhaust gas analyser- as used by any MOT testing centre --and get the fuel air ratio checked -- symptoms do sound like over fuelling

 

[Robbarr88]

Thanks Grober.

im back to work tomorrow so when i get back in a few weeks il check that out, i tried uploading a video but it wont let me due to the size.

 

[optimusprime]

Rob get a bottle of RED X pop it in the tank and then give it a good run . [ sticking valve ]

 

[Robbarr88]

Thanks optimusprime, i will do its been nut and bolt rebuilt, loads of welding, hence been stood, once its painted and back on road il be taking it for a good run thanks again!

 

[Robbarr88]

Hi Guys, bit of an old thread resurrection here.

But unfortunately the problem lives on, so since the thread started the car has now had the following items fitted.

New loom
New HT leads and plugs
Cat removed (to see if was blocked and refitted)
New fuel pump and filter.

There is however some progress, the car will start and rev with help, from 2-4k and hold, lower RPM rev range 5-2000 RPM its jolty, and the engine is all over.

Now my thoughts of possible remaining faults are.

Faulty injector.
Lambda sensor.
Vacuum lines.

These are the last few things i can try before i call it quits and get a specialist in, any other ideas please fire them over im open to trying everything before i pack in.

Thanks again Guys.

Rob.

 

[Robbarr88]

Or possibly throttle body idle control??

 

[wrdcc01]

Is your wiring harness from Mercedes/Delphi or is it a rebuilt/refurb one? I don't always believe in coincidence but not much should have happened in 6 months of storage. If you want to spend an hour and no money I would recommend getting out a multimeter and checking continuity of each pin from the ECU to the components. Did any water get anywhere near the ECU or OVP relay. Go nuts with WD40!

 

[Robbarr88]

It was a refurbed unit from a reputable rebuilder who i sent my old loom and then repaired, but il check like you say and have a good look, willing to try anything at the moment! Cheers wrdcc01