Changed DMF to Solid Flywheel Conversion (Valeo) now Performance problem


New member
Citroen C4 1.6hdi
Hi Guys,

I am a new member of the forum. recently I have had my DMF changed to solid Flywheel conversion (Valeo) for my Citroen c4 1.6hdi (turbo) diesel 110bhp hatchback 55reg car. Since i have had it changed i can feel that my gas pedal is slow responding. previously when it had Dual Mass flywheel I could feel the torque. with a bit of press on the gas car used to pick up the speed..but now I don't feel that torque anymore.
I can press the gas to the full in a quick second but car will gain speed slowly. this is the way i can see the different. when I incline in a steep hill i don't feel the power of the car as well. Can someone explain if this is normal for a Solid Flywheel Conversion or people who did the job done something wrong.
I am eagerly waiting for the reply please.
Is the new solid SMF flywheel the same weight as the DMF as if they are the same IMO there should be no difference in performance.
I suspect that there may be something amiss in the induction system like say a split hose or a loose connection leaking boost pressure.

Have you spoken to the workshop/garage that carried out the conversion ??
Is the new solid SMF flywheel the same weight as the DMF as if they are the same IMO there should be no difference in performance.
I suspect that there may be something amiss in the induction system like say a split hose or a loose connection leaking boost pressure.

Have you spoken to the workshop/garage that carried out the conversion ??

Thanks a lot for your reply TCJBOLDIE. I don't really know whether they were same weight or not. The part was delivered to the garage when i was at work. I also thought that there might be connection or leaking air problem. I took the car to the person who got the job done.he test driven the car with me and finally said there was nothing wrong and i will be needing some time to get use to it. Furthermore he said if there were any connection or leaking air problem the engine light should be on straight away which is understandable.
Today I went to motorway to try the car again and i have found following difficulties
1. Need more effort (pump in the gas) to gain speed more than 85mph. previously i could just press the gas and speed rose up to 100mph without any effort. I could feel the grip of the gas pedal. Note that I am not was just to test the car.
2. Acceleration is very bad..when pressing the gas you can easily press it ll the way to the end and speed gains slowly.
3. Gas pedal respond very slowly.
4. When I was pressing the clutch and gas pedal i could hear a knocking sound from underneath of the car..sometimes it was coming from back of the car and sometime from the front. I thought may be knocking sound was coming from any metal objects of the boot..but i checked, there was nothing in there.
4. I felt another problem today. when i was driving at 70mph sudden braking was making the steering wheel shakes. I said sudden or sharp braking though..if i gently press then no problem. 50mph has no problem as well.
Please guys help me to get the torque that i used to have in my car.
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Common sense and or logic indicates that the flywheel should not be the culprit re your loss of power/torque.

This may seem far fetched but check the cold air inlet for blockages as it still seems to me that there is a problem somewhere in the airflow pre or post turbo.

Does your car have a DPF and is it ok??

The knocking could be a loose flywheel although doubtful.

Have you checked the wheel lug nuts as well as the wheel bearings as they can affect the wheel shakes in certain circumstances along with poorly balanced wheels so you may have lost a balance weight on a wheel which will lead to the shaking steering wheel feeling???

Warped discs or oval rear drums can/will give a pulsing/pedal feel when braking.

IF your repairer says it's perfect and you remain unconvinced then I would take it to a Citroen specialist for a second opinion.

Can you get another car the same to do a side by side acceleration test preferably on a track to see if the car is as slow as you say.

Hope this helps you track down the faults/problems you seem to have and let us know exactly what they are/were when they are rectified please.
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My car has DPF and I don't think DPF is causing gas pedal to response slow as gas pedal was working fine until the DMF changed. I also had my tyre tracked and wheel balanced couple of weeks ago. I had to change front two Anti-roll bar linkage ball joint last week. I don't know if this shaking is linked with it or not.
I am really a novice about car stuff. So do not know where to look at about the blockage in cold air inlet. I have already taken a big pipe out which runs from air box to turbo. cleaned inside and put it back. just need to check the air box now for air filter.I got a gut feeling that something must be wrong. I don't have any option to compare with another car side by side and also do not want to take it to citroen dealer as it will cost me an arm and a leg. I have already spent beyond my means to change the DMF. but keep posting me any ideas and suggestions please.
It wouldn't be the first time that a cleaning rag has been left in an inlet system ..V(

NOTE I am not familiar with your car so don't know what exactly had to be removed and replaced when the flywheel was changed.

The DPF may be clogged but even if not I recommend that you use a DPF friendly additive each fill as per directions on the container to prevent the known problems due mainly to small trips and low speed driving that does not generate sufficient heat not to burn off deposits that can lead to a blocked DPF.

Hopefully you are using a DPF compatible oil IF NOT that can lead to future problems.

Can you arrange to get a "smoke test" that can find the souse of any leak that may be out of sight and undetectable by eye to rule out any leaks in the inlet system as it can easily be carried out by someone with the machine quite easily and little cost ??

FWIW I had one done and it only cost app $80.00 Aussie dollars app 50 pounds in your money :)

Well that's about all I can suggest to help locate the cause of your difficulties :(

One last one that just came to mind Does your car have a "scan tool"port that can be hooked up to help shed light on the matter ???
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Thanks for your constant replying. Tomorrow i will go to that guy and ask him about the noise which was coming underneath of the car after pressing clutch and gear. hopefully he will have a look. Yes i did use lowsap oil to reduce the particle soot when i did servicing on 20th December 2016. I also use fuel additive always to keep the dpf cleaning.
I have MaxiScan, the basic code reader tool and it didn't give me any particular fault code. i will consider taking the car to someone else if the problem persist after tomorrow..but it is really hard to make the garage people understand the problem..they wont realise until they have driven it in motorway.
Hi guys,

Things have been sorted. I am so happy.
Worn out nearside Track Rod End was causing the banging sound.
Split vacuum pipe (connected with Solenoid Valve) was the culprit for acceleration problem.
Mechanic fixed the split pipe and after that the car is perfectly perfect now. I love the way it sounds. exactly this is the way it used to sound before.
Really glad you got it sorted and now others with a similar problem can refer to your thread and get the answer!

Keep in touch and please get involved in our many topics and discussions on here.
BUT the way you described the banging/knocking noise led me to thinking that it only arrived after the FW change ?-/

It seems that my first post was spot on re "split hose" :)

As your car has a few miles on the clock and IF your car has a wastegate I would replace the hose going to the wastegate actuator NOW with a quality silicone hose as any split will bleed off pressure to the wastegate actuator which remain closed and result in much higher boost pressures that can potentially result in a blown motor.

NOTE this applies to all turbos with a wastegate.

Check all rubber hoses including the radiator ones by squeezing to see if they are still flexible and not hardened over time and replace with new if if they don't feel right .I carry spare hoses, bulbs,belts and the basic tools needed to fit them.

Have had a IC pipe blow off at the track and the car lost boost pressure to the inlet manifold and still drove ok but slow.
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