rough running engine

[rog1]

Hi everyone,
this my first post due to no problems until now, car Ds3 Dsport plus Thp 155 has been running very lumpy on start up, when stopped in traffic and now has a stutter on hard acceleration. I've taken it in to the dealers who after asking many questions via prompts from citroen website?? after they put in the chassis number and spending the day with them now say they need to flush some fluid through to de carbon the engine ???? Has anyone experienced anything like this or heard of this or am I a long way behind of a long standing problem

[Jamie@SPTuning]

Yes, take a look at ours.

[Gazski66]

Yes, take a look at ours.

No blaster yet Jamie?

[rog1]

Hi Jamie,
will the flush??? cure the problem or is there more problems to come the pics don't look good I've done 15k miles to date does the mileage effect the situation

[Jamie@SPTuning]

Ours has done 28k...
Best solution for this is walnut blasting....
We've had the equipment on order to carry out this process for 10 weeks now, should be here very soon.
Can't see the chemical clean being as effective as a walnut blast somehow, plus your washing the crud through your engine with the chemical clean, the crud is vacuumed out when blasted.

[Jonbays]

I had the same Stuttering on my THP155 DS3.
http://www.ds3club.co.uk/showthread....r-acceleration
Mileage isn't the issue and the flush is just for wishful thinkers. Walnut blasting or cylinder head removal disassembly and chemical clean is the fix.

Yes this is a design fault in the THP series engines where the backs of the inlet valves and inlet tract will build up large amounts of carbon deposits in a relatively short amount of time not really mileage related. The higher the output THP engine versions with the more aggressive the valve timing and turbo boost the more problems you will have as in DS3 Racing for instance. Toyota couldn't fix this without auxiliary port fuel injectors to clean the back of the valves and GM seemed to manage with special valve timing for GDI direct injection turbo engines in particular. Honda stayed away from GDI for quite a while too for once not being an early adopter so interesting to see how they handle the issue. This is all first gen tubo GDI engine design issues that Citroen have walked away from discussing openly so hard to know what the real problem is. Lots of focus on the PCV system which may well help and some go for WMI water methanol injection systems but I bet the real answer will be found in combustion chamber design, valve timing and direct injector pressure spray pattern and timing.

[rog1]

Hi Jonbays and Jamie,
they've told me they want to take the car in for 2/3 days under warranty to do the chemical clean next week, I'm starting to really worry as when they gave me the car back after the initial look and diagnosis there was a bad rattle from the dash when ever you put the stereo on and just left bits they obviously disassembled in the passenger footwell. Should I tell them that this is a long standing problem with this particular engine and would like a better long term fix as from what you guys say its only set to come back again and get worse.

[Jonbays]

The chemical flush treatment is something that won't do much, might help a bit and won't hurt and takes an hour.

A chemical clean will require taking the head off and disassembling it and then cleaning it in a chemical bath then reassembling it all again. This will take a couple of weeks. 2- 3 days means they want to try the chemical flush treatment and see if it works. Ask if they have a fibre optic camera to take before and after pictures like Jamie's so you can see what the chemical flush treatment has done. I suspect they wont have one and or wont want to risk having to show you it doesn't work.

I can't diagnose your car but if it is stuttering on hard acceleration from excessive carbon build up it only gets worse.

I am certain that Citroen or BMW (whose engine design is at fault) can tune ECU so that the variable valve timing limits this happening easily enough but not without compromising emissions and power outputs.

[FLP]

Had the same problem. They flushed my engine in April. For now the stutter is gone, but I'm sure it'll be back some day. I'll be installing a catch can as soon as my warranty runs out next year..

[Toxic]

The Engine was designed by PSA/BMW though for the life of me i cannot see how the engine got so many awards for numerous years! http://info.citroen.co.uk/our-news/editorial/international-engine-of-the-year/

I think Walnut blasting AND Terraclean would be most beneficial to the whole engine/exhaust/catalitic convertor system. Its just not worth doing one without the other. the carbon build up with be through the whole system not just the inlet valves.

[lfcrule1972]

How much does a Walnut blast and Terraclean cost Toxic ? I just wondered if CUK could consider including these as part of the service items to ensure these engines (with no accepted issues by PSA/BMW) remain in best condition ? Obvs if the costs are huge then this won't happen, I know Jamie has a Walnut Blaster on order but I have no idea of the cost of the equipment needed....

[Toxic]

Terraclean is about 100-120 quid. you need to contact your local rep for that. think they have a facebook page or you can contact them via the webpage.

Yeah I was wondering too. BMW are starting to use Walnut blasting in some of their dealerships.

[Chris_Blue]

Decent fuel will help rog1
as a comparison, its either smokeless cleaner burning coal or standard sooty black smoke coal

[lfcrule1972]

as a comparison, its either smokeless cleaner burning coal or standard sooty black smoke coal

Nope, I'm :confused:

[Chris_Blue]

well- you would be lfc wouldnt you
its about cleaner burning fuel, and what fuel goes into the DS3