Flood water damaged c250d misfire and nox sensor fault HELP!!

[XJ600]

Pull the injectors and measure piston heights with a DTI gauge, compare with the other pistons. Will tell if a rod is bent.

 

[Jon2021]

I have now dropped the car off at a local engine specialist who will be taking apart the engine and rebuilding it as necessary. He suspects it is the rod and that its bent by mm’s as hes had a few thats come in before and they presented the exact same problem. Going to have to bite the bullet on this one. I will let you know how i get on. He says it should be ready by next week Wednesday so fingers crossed.

 

[E55BOF]

Good luck. I hope that the Nox sensor issue problem doesn't turn out to be a faulty ECU, though; I'd have had that sorted before committing to an engine stripdown.

 

[Petrol Pete]

A bent conrod was mentioned in post #3, got there in the end . As E55BOF advises the Nox sensor issue could still be with you. Keep us informed

 

[E55BOF]

Remember that diesels rely *entirely* (glow plugs complicate slightly) on compression to heat the air in the cylinder and allow it to fire once diesel is injected. A lack of compression is almost certainly your misfire cause. I think the glow plugs are helping from stone cold, then when they extinguish, you experience the misfire.

Aha! NOW the symptoms make sense to me. The low-compression pot fires OK when cold and the glow plugs are helping, then once they go off, misfires until the overall temperature of the engine rises enough that it starts firing again on compression alone. I learnt about diesel engines from that... Thank you.

OP, you'll still have the Nox sensors problem; does the chap doing the engine work have the diagnostic kit to sort them out too?

 

[BULLITTBOSS]

i am glad you got there in the end

 

[Jon2021]

Yes it started making perfect sense once I found out that the compression in cylinder 2 was slightly low. It wasn’t excessively low hence why it still started and drove pretty well considering the issue. As for the nox sensor issue once i had them replaced both sensors were showing up as having no signal however when the old ones were in it only stated one of them had a ‘component' issue. Im guessing it something to do with coding or they simply need updating because they are now both showing as having no signal whereas before it was only one and it had a component fault. Im pretty sure they were fitted correctly and the part numbers match so it must be software. Im not too concerned about that for now as they wouldnt cause a misfire and it is still 'driveable' but once i have this major issue resolved i will move on to fixing the nox issue. If it does turn out to be an ecu fault im sure i can pick one up second hand for pretty cheap and just have it programmed to the cars vin number and all should be well. Fingers crossed

 

[CarFan79]

Yes it started making perfect sense once I found out that the compression in cylinder 2 was slightly low. It wasn’t excessively low hence why it still started and drove pretty well considering the issue. As for the nox sensor issue once i had them replaced both sensors were showing up as having no signal however when the old ones were in it only stated one of them had a ‘component' issue. Im guessing it something to do with coding or they simply need updating because they are now both showing as having no signal whereas before it was only one and it had a component fault. Im pretty sure they were fitted correctly and the part numbers match so it must be software. Im not too concerned about that for now as they wouldnt cause a misfire and it is still 'driveable' but once i have this major issue resolved i will move on to fixing the nox issue. If it does turn out to be an ecu fault im sure i can pick one up second hand for pretty cheap and just have it programmed to the cars vin number and all should be well. Fingers crossed

Just remember that the dpf won't regen with the Nox sensor fault.

 

[Jon2021]

Just remember that the dpf won't regen with the Nox sensor fault.

I will be getting the dpf fully cleaned whilst they are rebuilding the engine

 

[Sasha2121]

Джон привет подскажи чем закончилась твоя проблема с движком у меня точно такая же проблема не могу разобраться

 

[whitenemesis]

Джон привет подскажи чем закончилась твоя проблема с движком у меня точно такая же проблема не могу разобраться

Пост на английском может быть лучше. Джона здесь не видели с апреля 2021 года.

 

[Sasha2121]

проблема

John hi tell me how your problem with the engine ended I have exactly the same problem I can’t figure it out

 

[zipdip]

I missed this thread first time round and enjoyed reading it,but hey another thread with no the car runs great now after ???? was done and the op has not been seen since April last year

 

[Mates]

John hi tell me how your problem with the engine ended I have exactly the same problem I can’t figure it out

Hy! Did you figured it out? I have the same problem now