Help! Intermittent Engine Fault That No-One Can Find!

[jadrake]

Hi,

 

I have a 53 plate diesel C8. I love my car. It takes me and my large family everywhere we want to go, with all our luggage. It's awesome EXCEPT ...

 

It has an intermitent engine fault. Let me explain:

 

95% of the time, she drives beautifully. No problems at all. 900 miles to the Lake district and back over Christmas - no problem.

 

Very occasionally, she will become sluggish and lose power. She jumps and jerks when around 2000 rpm. She can be driven, but it's not pleasant. If you park up, the engine is very sluggish. Putting your foot right down only raises the revs slowly to about 1500, then it races to 3500-4000. Usually there is black smoke, and the smell of unburnt diesel.

 

There is also a funny whirring, spinning sound from the passenger side of the engine compartment.

 

After a while, it all goes away and returns to normal.

 

Last night it happened, so I sat on the drive with the engine running and revved it a few times. Sluggish, then racing. Turned off and on again, same problem. Turned off and on again, all back to normal, like nothing had happened!

 

I've taken the car to 3 different garages - 1 Citroen dealer and 2 independents. Each time, it was playing up the night before, but when it got to the garage - perfectly well behaved. No faults logged either.

 

This is driving me crazy! I love my C8, but my wife is now refusing to drive it, as she's scared of it playing up when she's out alone.

 

Can anyone offer any advice? I have absolutely no idea where to start, and without a fault code or the car actually playing up at the garage, no-one else seems able to help.

 

Thanks,

 

Adam

[Simple]

What the car is doing is understood. But why? is what needs to be found... The ECU is not responding to real situation, and that may be wrong data coming to it or no data. Before doing anything in the Citroen C8, ensure you have a good well charged battery, if not, you are chasing a red herring.

 

- If one of the sensors that feeds data concerning engine running to the ECU is faulty such that it gives wrong data, it will lead to the ECU giving wrong fuel mixture etc..

 

- If the flow of air and/or diesel is interfered with, it will also lead the engine to misbehave.

 

1- Concentrate on the MAF sensor. could be faulty or bad connector.

2- The Accelerator sensor, may need adjusting or cleaning.

3- The Vacuum solenoids. near the accelerator sensor.

4- Cam sensor.

 

Q1- How many miles/kilometers are on the clock?

Q2- Does the car give this trouble on regular mileage bases (every 300-500 KM), if not driven long distance?

Q3- Do you hear any hissing noise (air leakage), in the engine bay, when you turn the engine off (you need to have the bonnet open before turning the engine off).

Edited January 9, 2016 by Simple

[paul.h]

Welcome to the forum.

 

Which engine does your car have, size, bhp ?

 

It is possible the car is regenerating the exhaust dpf filter if it has one. A Citroen dealer or other with Lexia diagnostic equipment should be able to see when the dpf was last regenerated.

[jadrake]

Thanks for the rapid responses!

 

Sorry - forgot to put the all-important stuff: 2.2l HDi

[coastline taxis]

hi with any faults like this theres only one thing that can help you  (without spending thoushands) and im very surprised no garage has offered it to you. without being big headed they really musnt no what there doing. Anyway get one of theese we use them all the time for faults like this

 

http://www.ebay.co.uk/itm/OTC-InfoLoggerTM-Data-Recorder-Logger-Kit-3005-/141355701598?hash=item20e974d55e:g:XVAAAOSwGvhTz~Ld

 

Just keep reseting it and plug it in everytime you use the car. then when it does happen you have it recorded. then upload it and they give you the codes and get back to us

[paul.h]

Your car will have an exhaust dpf (diesel particulate filter) so it is possible regeneration of this could be happening. Replacement/cleaning of these is around 70k miles as well as topping up the eolys fluid. How many miles has the car done and do you know if the dpf has been replaced ?