OK, major issue now...

Hi All, new to the forum.
I got my GT Diesel back in late March, first one off the boat in Melbourne I'm told. Very happy with it, already chugged up 11,000km in that time.

Have had a gripe since new that Mazda think doesn't exist - after cruising on the freeway for anything more than around 15 minutes at 100km/h (~60mph), the i-stop light goes out, fuel consumption goes up by around 20-25% on flat roads, and if I come to a stop in traffic (as is often the case in Melbourne's peak hour), the engine revs at around 800rpm as opposed to the normal 650-700.
I often find it 'comes good' again after 10-15 minutes of urban driving, and the i-stop comes back on again. This is repeatable - can go back on the freeway and the whole thing repeats after 15km or so.

Have asked local dealer to check this twice, each time saying they couldn't find any problem.

Anyhow, most of my travel is stop/start in metropolitan traffic, so no big deal normally.


Well, today, my wife took a drive of about 25km to a friends new home for a housewarming, and calls me up when she arrives. "The car is all juddery and there are warning lights on.

I just so happen to have the CX-5 manual at home, so I check what they mean.
1) Engine symbol
2) Traction Control symbol
3) Tyre Pressure warning symbol.

jumped in her car to check it out. Tyres normal. Drove down the road and notice the gearbox is not changing gears correctly. Seems to rev very high when accelerating and changes gear very late, even under very gentle acceleration; and feels like its going to stall when braking, to the point that when it does change down, the car lurches forward - hence the juddery behavior reported by the wife.

So I leave her Mazda-2 with her and take my sick puppy the 25km home for some TLC.

I noted that when switching from AT to MT, the display (that normally shows an 'M' plus the current gear) was showing just an 'M', and cannot manually change gear any more.

My feeling is the ECU is screwed up - the fact it's showing a traction control warning light, engine warning light and tyre pressure warning is bizarre.

Has anyone heard or seen anything like this? I saw a video on youtube on a Mazda-3 that looks just like this.

Not sure if the two issues are linked, but my gut tells me they are.

Thanks!

Chris

Sounds like a big issue. I would bring it to the dealer asap.

I don't know enough about the CX-5 to make an assumption about what the problem could be.

Good luck

If it were me id probably disconnect the battery for a bit and see if the ecu resets. Hope you get it sorted out.

Regarding fuel consumption increase, and probably the increased revs too, I think this will be related to dpf cycle. I have experienced similar on my cx5 diesel too, my understanding is that this is normal behaviour especially when travelling at reasonable speed on a highway/motorway. Happens in other diesel vehicles with dpf too.

Thanks for the replies - I dropped it in to my dealer this morning, heading off overseas this afternoon, so have left it with them to work out, great to deal with and seemed confident it was not a huge issue - we'll see!

As for your reply, pauly69, can you explain what the dpf cycle is? not heard of this before, first time diesel driver

Sorry daviescr, I'm no expert - since their introduction (must be getting on for 10 years now in mainstream cars) diesel particulate filters have been improved, I'm not sure how the system in the CX5 works, but if you google something like dpf regeneration you will find lots of discussion.

I believe that depending on your overall style of driving there may be a requirement for the engine to actively raise exhaust gas temperatures to help burn off particulates / clear the dpf, and that this is partly achieved by burning additional fuel, hence the temporary fuel consumption increase / higher revs. This doesn't happen exclusively on highways, but I think the conditions required to achieve an efficient regeneration are better met during that type of driving.

I could go on but due to my limited knowledge I would probably end up misinforming you. Suffice to say I am happy that is a fairly standard feature of modern diesel engines.

wiki has a decent write-up...
http://en.wikipedia.org/wiki/Diesel_particulate_filter

There is another post here in the CX-5 forum about KNOCK SENSOR, where the repair performed by MAZDA. The repair for some some strange electrical gremlins was removing a sliver of metal that was shorting some stuff on the ECU. Perhaps this might be more common?

daviescr - Let us know upon return what the dealer said...

I'm very curious

Sounds like a similar issue my car just had yesterday. See my post "warning lights and 4,000 miles." I had 4 warning lights but 3 are the same as yours. I'm still waiting on the dealer to tell me what's wrong.

Interesting because this happened to me about a month ago. I have the CX-5 GT not diesel.

I was driving down hill letting go of the gas pedal and the engine suddenly downshifted to third gear and just got stuck and revved really high til i got to the stop light. Then as I was accelerating from a complete stop I noticed the car revving very high and not changing to the 2nd gear until really late - which i think is a safety feature of the manu-matic to minimize damage to engine if accidentally left in gear. The gear panel is showing M even though I was on Automatic. Anyway after that I noticed all those lights flashing and I decided to pull over and see what's up. Turned off the engine and read the manual. I was confused because it said a problem with traction control as well as engine light. Turned the car back on and the problem went away.

I drove cautiously for about 30 miles while I was on the freeway. Was a little scared that I would blow up the engine in case the gear got stuck again while going really fast.

Never happened again though so I never bothered to take it to the dealership. Please let me know what the techs find out on yours.

Did your problem go away after turning engine off and on?

Any news this month?

I have now seen here multiple threads detailing these near exact symptoms, illuminated dummy lights included.
But, still doesn't seem there is absolute answers...

I am also interested in an update.

Yes please, we would like an update.

I haven't noticed multiple threads on this kind of symptom(s) and with multiple warning lights (CX-5-related that is).

The multiple warning light situation accompanied by a minor problem seems to be a bit more common with Toyota/Lexus vehicles.

as another member posted, that sounds like a DPF regen cycle. My BMW 335d does this as well. It's a totally normal emissions related process with modern diesels. Personally, I hate it because there is no control over when it happens and no indicator that it's happening (other that the car feels as you described).

jeebusm3 said:

as another member posted, that sounds like a DPF regen cycle. My BMW 335d does this as well. It's a totally normal emissions related process with modern diesels. Personally, I hate it because there is no control over when it happens and no indicator that it's happening (other that the car feels as you described).

Click to expand...

absolutely correct. this is the one downside to a non-urea injection system like "ford" has in their diesel trucks... it's another fluid tank to fill... extra fuel is added at intervals to burn hotter, and regenerate the DPF.. if this were a urea injection system you would not have this issue. it's all to maintain emissions numbers.. CO2/SO2 & other particulates.. the downside to urea injection is having to fill another tank with another fluid.. yes it's relatively cheap, but the additional system makes everything more expensive, heavier... etc....