C8, Lack Of Power

[Clarklei]

We have a 53 plate c8 and have currently got a power problem with it. The car has no power when pulling away or on hills. It is really sluggish but once we have got up to speed we're ok until we hit another hill or have to slow down. Motorways are nightmare.

 

We've had an anti pollution fault for the last couple of years which hasn't yet been sorted as as soon as we fix one fault it says it's something else.

 

. The diagnostic said there was no vacuum out of solinode or air flow sensor wasn't at full efficiency. So far they disconnected the airflow sensor which made no difference, and swapped the turbo solinodes over and that made no difference either.

 

Any ideas anybody pls?

 

Coming up to a dead end at the moment,

[paul.h]

Welcome to the forum.

 

Have you tried replacing the fuel filter yet ?

[Clarklei]

Thank you

 

Yes the fuel filter was the first thing they replaced, twice cos it happened again just after so thought it was a faulty one.

Edited March 17, 2015 by Clarklei

[paul.h]

If disconnecting the air flow sensor (MAF sensor) which is usually in the air ducting just after the air filter, made no difference then this is often an indication it could be faulty. You could try to clean it using something like carburettor cleaner but if this does not work then a new one may be needed. If you have the fault codes you could put them on here since it may point somebody towards a possible cause of the fault.

 

Also, which engine do you have - diesel/petrol/size/bhp is a dpf fitted ?

[rfhspares]

I'm wondering if It could be egr valve stuck partially open. My Mercedes a170 had a similar fault and power was so low I could not pull away in a hill. cleaned the egr and it was fine.

[Clarklei]

If disconnecting the air flow sensor (MAF sensor) which is usually in the air ducting just after the air filter, made no difference then this is often an indication it could be faulty. You could try to clean it using something like carburettor cleaner but if this does not work then a new one may be needed. If you have the fault codes you could put them on here since it may point somebody towards a possible cause of the fault.

 

Also, which engine do you have - diesel/petrol/size/bhp is a dpf fitted ?

We have a diesel 2.2 and yes we have a dpf.

[paul.h]

If the engine management light is on the engine may be in limp mode which will limit the performance so emissions are not too high.

 

On the 2.2 hdi 136 bhp engine there is a swirl flap actuator at the gearbox end of the cylinder head. On the C5 the plastic cup on the arm often breaks so it comes off the ball of the pivot. If it is not broken, get somebody to start the engine and check the arm moves so you know the actuator is ok - Citroen call it a diaphragm, part no. 036394 (check this using your VIN) and the diaphragm in it can also fail. This is in the C5 Technical section Common Problems pinned topic but on the C5 it has a different part no:

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11. C5 2.2 hdi 136 hp only, swirl plate diaphragm actuator ball cup breaks.

Vacuum leak/turbo fault codes (any engine).

Located at the left end of the cylinder head. Symptoms may be loss of acceleration, engine management light, increased fuel economy. The plastic ball cup may be replaced on its own (10 mins) or the complete actuator replaced (several hours DIY), about £20 but the cup is not available separately. This topic has a few notes on how to replace the part http://www.citroen-o...ragm#entry40936

 

There is a diy fix here if not able or want to get the dealer part http://www.citroen-o...-to/#entry82945

 

I read in Car Mechanics a case where the actuator had a vacuum leak which resulted in the engine management light and limp mode and fault codes for over boost and turbo regulation fault. The slow loss of vacuum reduced it also to the turbo wastegate so turbo boost level dropped, the ecu then increased the boost control duty cycle which then deactivated the swirl control increasing the vacuum boost and tripping the EML/limp mode. These fault codes have also been reported here and it turned out to be a split in the vacuum pipe to the egr valve actuator - so any cause of a vacuum leak should be looked for before touching the turbo.

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At around 80k miles the dpf needs to be serviced (cleaned/replaced) and the eolys fluid topped up - has this been done ? If not and the dpf is not working it could block up with soot and limit performance but you may get warning messages if this happened.