Slight misfire just got worse

[StockholmSyndrome]

For the last month, my 185 D5 would occasionally produce a slight misfire while driving, usually after turning a sharp corner or a roundabout, after a second or two it would disappear.

Two days ago I replaced my clutch, DMF and rear main seal, and now it is much, much worse. Once up to motorway speeds it drives well, however at low speeds the car is misfiring frequently, and occasionally a large bump or corner will cause it to lose all power and cut out once you dip the clutch pedal. So far I have concluded that it is most likely to cut out when the engine is cold.

These are the parts I disturbed when doing the clutch that may be relevant to this new fault:-

- Control unit atop the airbox & the two looms going to it
- Air mass meter & airbox assembly
- All intercooler hoses
- Vacuum lines & both vacuum engine mounts
- The plastic pipework going to the DPF pressure sensor


I think it's worth mentioning that during the clutch job I noticed that all 5 engine mounts were in very poor condition, and there is a slight boost leak coming from the turbo resonator elbow, which I am awaiting a new part for.

No EML present.

[StockholmSyndrome]

Update, after a week back on the road the misfire has returned to how it was before the clutch job. I'm wondering if it had anything to do with the fact that the battery was disconnected for a few days?

I have also replaced the leaking turbo resonator pipe, however this made no difference to how it drives.

Still no fault codes, No EML, temperature no longer seems relevant

[Joe the great]

Sounds like bad connection or bad earth on the engine.

[StockholmSyndrome]

Thanks Joe I will try cleaning up the earth connections

[StockholmSyndrome]

Checked and cleaned up earth strap eyelets, no visible corrosion and bolts tight, no change in drive.

I have noticed it gets slightly worse when the diesel is low, could this explain why it was so bad after the clutch job? The car was off the road for a few days and was low on fuel, could it have something to do with fuel pressure?

[Simmy]

how long since the fuel filter was changed? also check out the wires and connections to the lnjectors have you ran any kind of diagnostics to search for faults?

[StockholmSyndrome]

Fuel filter was changed by previous owner at 197000 and now on 209000, however no proof that this was a OE filter so that's next on my list so I can rule it out.

I haven't checked continuity through the injector loom however a visual check showed no breaks.

No fault codes

[StockholmSyndrome]

Fuel filter replaced with a genuine part and no difference. Misfire under load still present, some days better than others, intermittent loss of throttle response then cutting out now once a week regardless of fuel level. Will likely take the car to a specialist next week as it's not safe to drive it as is.