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Mike, Technician
Category: Mazda
Satisfied Customers: 39198
Experience:  Tech Expert
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Hello, i have a 2006 mazda 6 2.0 ts diesel estate (143bhp) The

Customer Question

Hello, i have a 2006 mazda 6 2.0 ts diesel estate (143bhp)
The problem i have is quite a hard shudder when accelerating and i can hear a quiet tick, tick tick noise from in the car presumably from under the bonnet. If you accelerate hard in 1st and 2nd it is hardly noticable but 3rd to 6th is where its at. a couple of local garages have said different things, injector at fault, possibly dpf blocked?? The dpf light does work but not on when driving but the management light is on a few minutes after every start up. The other day i was driving and heard a loud bang from the engine and greyish blue smoke billowed from the exhaust followed by the quiet tick,tick tick becoming a loud knock knock knock. i switched engine off and restarted after a few minutes and it was running fine after that, just the shudder and tick tick tick noise. One garages scanner brought up code U3FF but no trace of this code can be found. I have had this car 3 months and already had a new DMF as that was causing a vibration also. Does my problem sound familiar at all? Any help would be appreciated as a diagnosis without dealer prices would be of great help...The garage that thought a DPF issue said on tickover, there was not much pressure blowing out the exhaust. Thank you. Mark
Submitted: 5 years ago.
Category: Mazda
Expert:  Walt-mod replied 5 years ago.

I'm a moderator for this topic. I've been working hard to find a Professional to assist you right away, but sometimes finding the right professional can take a little longer than expected.

I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.

Thank you!
Customer: replied 5 years ago.

Thank you. I will await your findings. It seems that sometimes the car feels like a minor mis fire now and again also, whether thats connected or not. The fault code i stated is the only one showing. No other fault codes. There is a very peculiar strong smell from the back end of the car now and again if of any help, maybe a dpf blocked? but would a blocked dpf cause the quiet knock sound?

Expert:  Walt-mod replied 5 years ago.
Thank you for your continued patience. We will continue the search for a professional for you.
Customer: replied 5 years ago.

Thank you. I may add that the shudder/vibration occours when engine revs are below 2500rpm.

Expert:  Mike replied 5 years ago.
Hello and Welcome to justanswer...

My name is MIKE - Im happy to help you with this...

What is the mileage on the car?

What is its service /recent repair history?

Do you have any fault lights on the dash when driving at all?

Is the vehicle down on power overall -? can you feel the turbo kick in ever ? Is there any excess smoke still / now?

Rgds- MIKE...............................
Customer: replied 5 years ago.

Hi Mike


Thank you for your reply.


The mileage is currently just over 70,000 miles


Just a month ago it had a new dual mass flywheel fitted, The clutch plates and assembly were in excellent order so were not replaced.


The last recorded service was at 66,732 miles with an oil and filter change.


There is just the MIL light showing on the dash which comes on approx 5 mins after start up (assuming that something warming up) and stays on constant.


It does feel as if it is slightly down on power (143bhp) when asked to work hard and occasionally feels as if its misfiring or something on fuel line blocked. It does smoke occasionally (blueish/grey colour)


On tickover there does not feel as if much is blowing out the exhaust when you put your palm to pipe end and has a sound from the exhaust like a compressor chuff. I can hear the turbo whistle as you gently rev engine when stood still and feels like its working when driving with no black smoke. A few days ago i was driving steady away when all of a sudden a loud bank came from under the bonnet followed by blueish/grey smoke billowing from the back end followed by a loud knock, knock knock on tickover stood still.

I stopped the engine, let it settle a few mins, then tried re starting which it did no problem and ran as before after that. (fine but still with shudder and a quiet tick, tick, tick sound which goes when you accelerate harder and turns into the shudder.)

I have tried to give as much info as possible. Could this be something an injector out could cause or does this sound like a multitude of things happening all at once. I have had car looked at by 2 local garages (non mazda) one thought it be an injector at fault and the other could only find a fault code U3FF showing and thought a blocked dpf due to the lack of pressure blowing out the exhaust on tickover. I hope this helps as i fear taking car to a mazda dealer for diagnosis may lead to me being ripped off without half a clue before going in. Best regards, Mark. The car is a 2006 mazda 6 ts diesel estate 143bhp. Thank you

Expert:  Mike replied 5 years ago.
Hello again Mark -

Thank you for your reply and info..

With "noises" it can be very difficult for us here so the best thing I can do in such circumstances is to offer advice as to how to trace the cause down..

The best way to do this is to use a mechanics stethoscope or similar and physically listen all around the engine for this ticking noise.. and I would suggest to start at the inlet manifold - some of these have what are called Swirl Flaps inside the inlet manifold chamber and that would be my first suspect given what you described with the bang noise etc.. After that area, I would suggest check the turbo / area - and from there my suspects to check would be injector pump / injectors.

Its possible you have an issue with the replacement Dmf.. ( flywheel ) its not unheard off - so do bear that in mind - but that wouldn't normally add up with the bang noise and subsequent smoke - as opposed to the other items mentioned above.. So thats the best advice on this one Mark to get this traced down - Let me know how you get on..

The fault code by the way is irrelevant to this -thats usually down to communication faults - a mis match with the machine used. I would progress initially as above -and then as you have the engine fault light on, you will if you cant trace it, have to then have it plugged in to a machine to suit the cars systems to get the fault code out of it -

Let me know if you need anything more on this at all -

Meantime -- Please click on the OK rating to Excellent ratings service for me now, Thank you for that... and you can get back to me anytime if you need / wish..

Best Rgds, MIKE.

Please note, you are rating the content of my "answer" - my help to you - not the "system" which can experience delays etc which are not under my personal control -or delays caused by "time -off" which we all have on occasion - Thank you.

Customer: replied 5 years ago.

Thank you for your help in this matter. May i just finally ask, could the swirl flaps or a turbo issue be causing the shudder if it is one of those that is the problem?