Mazda 6 2.2 Diesel Problems

mikebn1952

I have a 64 plate Maxda 6 2.2 ltr diesel. A few weeks ago it developed a problem. With a light touch on the accelerator the car stuttered or hunted momentarily. If I put the accelerator down further it pulled away with power fine. My local garage have investigated and checked that the exhaust gas recirculation control systems and exhaust recirculation cooling system is working fine. They also checked the 4 diesel injectors and again all is working to standard. The garage had to admit that they didn't know at this stage what the problem is. They checked the engine management system and no errors showed up. Their advice was to continue driving until the problem worsened so they could then identify what the problem is. I've checked various web forums and nobody else seems to have experienced the same problem as me. Any advice please.

noclaf

Which forums have you checked? Might be worth (unless you have already done so) checking pistonheads and possibly honestjohn. I recall there were a lot of known issues with the previous gen 2.2 diesel that Mazda used but apparently they had sorted the issues with the newer incarnation.
Out of interest what are your typical journeys like, short stop start or longer runs? Wondering if it's a dpf or egr related issue causing the engine to go into limp mode

mikebn1952

My typical journeys are short ones - 3 to 10 miles with some longer runs up to 100 miles occasionally.
The symptom I have described only lasts a second or two at most.
Thanks for the suggested forums; I'll have a look at them.

DoaM

Regular 3-10 mile journeys are bad for a diesel which has a DPF, unless there is at least one long continuous journey (50+ miles) every 2 weeks at a minimum, preferably every week. The engine needs to get up to full working temperature to allow the DPF (and EGR valve) to clear soot/ash etc.

EdGasketTheSecond

When will they invent 'quick-change DPF' so you can fit it for the MoT and use a straight-thru pipe the rest of the time

Johnmcl7

I've found mazda6oc.co.uk to be the most useful for Mazda6 information although it's still very quiet, Mazdas don't seem that popular in the UK so there doesn't seem to be much active discussion on them.

How many miles has the car done? Does the problem occur all the time or intermittently? My Mazda6 is petrol but my previous Skoda Octavia was a diesel and it was bad for hesitating when it was trying to regenerate the DPF which it started doing a lot more regularly. If you put your foot down it was fine but on light use it would hesitate.

Goudy

Could be the EGR valve might be gunked up and slow to close.
You tend to notice this when on a steady cruise on a light throttle and then just steadily increase speed a little, it feels like a stutter as you press the pedal.

EGR opens when the engine is running on light throttle which causes a lean combustion, this tends to be very hot and that produces more NOx. The EGR feed exhaust gas back around into the intake, this hasn't much air in it, so cools combustion a little, reducing NOx.

When you open the throttle the valve should close, if it's gunked up (blowby oil and soot) it might be sticky and not close fully/quickly causing the stutter/hesitation.

Open the throttle fully and it masks the stutter but you often get black smoke from the tail pipe as the engine is now effectively running rich (exhaust gas is replacing the air) which can cause havoc with the DPF.

You won't get a code/EML until it fails to open or close a couple of times in one drive cycle.

You could really do with someone logging the EGR with a proper Mazda scan tool while it's being driven to see if it's operating properly.


With older euro 4 or 5 cars with less sophisticated vacuum EGRs, the trick was to give them a short sharp clout to free them up, but I wouldn't smack these modern electronic valves.

rsvtoddy

How often do you check the oil level? The Mazda diesel is (was) known for dumping diesel into the engine if the dpf regen was interrupted. Your sort of usage is not good for a diesel!

DaveMustaine

There just recently has been a recall on Mazda 6 2.2 Diesels for issues with carbon and soot build up within the engine, I had a similar issue to yourself I have a 65 plate and have done 70,000 miles. My car went into Mazda and they changed a valve and then booked it back in and did a carbon clean of my engine which took a day for them to complete. All this work was done free and the issue you are describing has now gone and my car drives as it should. Perhaps you can contact your local Mazda dealer and see if your car qualifies.

kirmal12

There are Mazda groups on Facebook that are helpful. Not sure many frequent forums as much these days. There is a Mazda 6 Uk group that is fairly active. I'm on the CX5 group and they are really helpful.

mikebn1952

All - I booked my Mazda 6 into the local Mazda dealers last week to do a full diagnostics exercise on the car. They found no errors logged on the engine management system but suspect that there is a build up of carbon on the inlet somewhere and informed me that Mazda do a clean of the likely affected part of the engine AT NO CHARGE. This requires a full day at the garage. This sounds to me like there is a design fault known by Mazda and hence their agreement to do the clean up FOC. I will give feedback to this site once this work has been completed later this week. Here's hoping my motor will be cured!!