C124 E220 misfire running out of ideas

[GRHunter]

Hi
I have been looking after my C124 E220 1992 for 5 years and I have done a lot of work on her. She has a problem with a very lumpy engine at less than 2500rpm.
The following have been checked:
No OBD1 error codes on pin 6, (she has the new silicon harness)
Runs perfectly when cold up to 65deg, throttle body is moving the as it should to maintain nice tick over
After 60deg tick over becomes lumpy and poor power until suddenly at 2500rpm it runs ok, maybe a little down on power
Plugs new and all look good
No sign of a inlet manifold leek
Any thoughts as to my next move?
Thanks
Geoff

 

[chris clk320]

I have a similar issue that I am just trying to diagnose, mines slightly lumpy when cold then absolutely fine for ages but when hot after a 30min drive, stationary and I. Drive suddenly it sounds like it’s dropped a cylinder no power but will clear if revved or driven for another few 100m.
Advice seems to be either ecu coil packs or ht leads. Trouble is I cannot replicate it on the driveway it even when hot and I have the old code reader system so need a flashing reader.
On yours check the fuel pressure valve when running pull off the vaccine line and see if fuel is dripping if so replace may sort the issue.

 

[optimusprime]

Had a misfire 2 x . once on W123. and again years later om a W124t Both times it was HT leads

 

[grober]

FAULTY throttle position sensor [at top of accelerator pedal in cabin] if you have a non mechanical throttle linkage??
Symptoms of a faulty throttle position sensor include poor acceleration, rough idling, stalling, erratic throttle response, and a Check Engine light on.

 

[chris clk320]

FAULTY throttle position sensor [at top of accelerator pedal in cabin] if you have a non mechanical throttle linkage??
Symptoms of a faulty throttle position sensor include poor acceleration, rough idling, stalling, erratic throttle response, and a Check Engine light on.

Thanks sounds like it might be, I guess these can be intermittent when on the way out and HT leads are an easy change. I did wiggle all of the leads but couldn’t replicate.
I did notice a fair bit of oil in the air intake side of the throttle body which seemed odd.

 

[grober]

Thats too much oil! There's a breather pipe from the cam cover to this area of the inlet manifold--IF THE ENGINE IS BLOWING A BIT OF OIL WHEN HOT? Then this could be a problem?

 

[chris clk320]

View attachment 166653


Thats too much oil! There's a breather pipe from the cam cover to this area of the inlet manifold--IF THE ENGINE IS BLOWING A BIT OF OIL WHEN HOT? Then this could be a problem?

I did feel there was a bit of blow by, ie pressurisation when oil filler cap is off when running it’s quite strong and spits a bit of oil other reports suggest this is normal but maybe not

 

[optimusprime]

So i would go for a item by the name of - RED X ..open up the spark plug holes, and put an egg cup full in to each cylinder .Next , let it do its work over night .Next day cover the plug holes with a cloth to catch exiting RED X then spin the engine over .Next step is repace spark plugs.Then start the engine up --important dont do this if people are about, reason is , it will fill the street with smoke as all old ccarbon is burned off. Its worth a try for the price . You can buy this from Halfords

Petrol Fuel System Cleaner | Redex

One shot of Redex Petrol System Cleaner fuel additives can keep fuel injectors clear – improving fuel economy and car performance.

www.redexadditives.com

 

[alabbasi]

Do these have the same ignition insulator problem that the m104 and m119 have?
Wiring harness been replaced recently?

 

[chris clk320]

So i changed the MAF sensor and air filter and it seemed to run better, took it for a spin thought i had solved the issue. then back at teh garage i topped up the oil ( i think this is a concidence) and then it started running rough ie sounds like its dropped the cylinder.
Anyway i unplugged the MAF sensor to see if that made any difference whilst running, and unfortunately when plugging back in, the MAF sensor cable shorted and burnt out! SO i now have to look for a new loom.

On further inspection the loom was fubar back to the bulkhead so iguess it was only a matter of time.

Now im worried about spending a packet on the loom only to still have an undignosed issue!

 

[optimusprime]

Do these have the same ignition insulator problem that the m104 and m119 have?
Wiring harness been replaced recently?

Looks like biodegradeable wiring loom ..he found this out on the maf Must be more the same .

 

[chris clk320]

So an update rebuilt loom back in the car along with new coil wiring and throttle body wiring.
Seemed to run nice for about 30 mins starts much quicker and seems sharper alround
then slight miss on idle now getting worse. Not as bad as at the start but not right. Generally it’s in drive when in traffic then seems to run fine when underway.
Next stop is replace the MAF as it’s running on the original and I have new sparks and see what that does
Then HT leads
Then coil packs
Anything else to throw into the mix?

 

[optimusprime]

I think once thats been done, you will be fine, and runnimg on all fours . ,

 

[chris clk320]

So I changed the MAF sensor and problem is still there. I decided to change the sparks so pulled them out 3 looked worn but ok cylinder 3 though was dripping in what looked like oil. Could have been old petrol?
They also were not particularly tight and cylinder3 I would say was only finger tight.
As they hadn’t sent the correct sparks I replaced them reasonably tight.
The car seems to run better but still with intermittent miss/cough.
Any idea about the amount of oil?

 

[optimusprime]

Oil leak above the spark plug ,and oil is then pooling inside the plug hole, and as you remove it the oil runs down the plug on to the threads . That can cause misfire

 

[chris clk320]

Oil leak above the spark plug ,and oil is then pooling inside the plug hole, and as you remove it the oil runs down the plug on to the threads . That can cause misfire

Hi
Could it be rocket gasket?
The plug recess in rocker cover seems dry except this one hole?

 

[optimusprime]

Yes it could .But i was not cirtain about your engine lay out at the time ..If there is a gasket above the plugs can you see where oils run down .? I will look at the type of e..ngine you have and come back

 

[optimusprime]

I recon this is your engine ..And to be honest it will be a far bigger job
replace spark plugs on mercedes W124 e220 engine i will fin another video on the job you will need to do

 

[optimusprime]

This is the job that needs doing , give me a like if your happy with my help . [for example ]not your emgine

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[chris clk320]

Mine is the 220 m111.960 engine, I think there are o ring seals as part of the rocker cover so this could explain the oil, I don’t see how it would create the rough running if plugs are tight. But not right in any case.