Hello All,

Summary:
1)Trouble with intermittent low power at all speeds, sometimes will struggle from 20 to 40 and then happily go to 60, sometimes will struggle with foot down to floor at 40.
2)traction control + IStop turning on when accelerating at speeds above 60Mph on motorway, once in this state will start making cranking noises and jerking when slowing down.
2.5) Issue 2 will go away, jerking and noises included after engine restarted.
3) Po299 turned on during a single test on the motorway at the same time as issue 2. Local garage checked it superficially didnt find any turbo leaks and cleared the fault.

Im not drivjng it on the motorway until can get sorted but issue 2 has happend once on an A road also.

Any ideas?? IStop makes me think battery but no idea how this would be related to traction control or turbo issues suggested by po299. Unless two separate issues for the price of one?
89000miles , 2016 plate.
Thanks In advance,
Alex



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*Update*

​​​​​DPF light started flashing today.
Wonder if it's the cause, or a symptom of the low power driving.

Putting it into a shop on Monday. Will update on here.

 

P0299 is turbo related, can be caused by faulty exhaust pressure sensor & also by a broken bypass valve/wastegate.

 

Had it looked at , manifold blocked up with carbon.

Going to try get the manifold and the DPF cleaned tomorrow. Will report back if that fixes other issues.

 

The clean of the intake and DPF did not sort the DCS/TCS + ISTOP issue happening at higher speeds.

I will try the below myself and report back.

 

Experiencing the same issue. My garage diagnosed a P0299, and mentioned it could be a sensor. I ordered a new MAF sensor, replaced it (the one I had was full of soot and oily grime) but the issue persist. I believe it is a dirty mainfold (My EGR was removed by remap and disconnected). I would love to know if the issue was resolved by cleaning the intake mainfold or if the SHY618W00 sensor did the trick.

 

Intake manifold and dpf clean by a mobile tech in Sussex area came to £590, it has improved performance when stepping on the gas.

However the Istop , dcs/tcs issue + po299 issue when accelerating between 60-70 persists. I will be attempting the exhaust pressure sensor change from the YouTube video in my last reply tomorrow. I think that might be different to the MAF sensor, not 100% sure though.
I will report back on whether that helps the issue.

Good luck,
Alex.

 

Hi Alex, yes, the sensor you are replacing I guess it has been a source of troubles for mazda. It has gone through 4 updates, so something wasn't working there.

In my case I wasn't getting any DPF-related issue, car feels with no power under 3000rpms and completely normal after that. I hope that sensor works for you and the problem is resolved. In my case I am not getting the dcs scbs tmps all the time, just during motorway speeds and quite randomly.

I hope that the exhaust pressure sensor works for you! Best of luck and let us know! Fingers crossed!

 

I replaced the exhaust pressure sensor, below is a better video that the previous one I think in terms of instructions.

The sensor did look a little clogged but not fully, see old sensory below. There is improvement to acceleration at below 60 with the new one in.



Unfortunately the same issue with the dcs/TCS + istop lights happened again when accelerating between 65-75 to overtake on motorway. (No engine light po299 this time).

Interestingly the mentioned lights turned on right after a period of the car doing high revs (4500) while I pushed the accelerator to go to 70+ to overtake, as if it wasnt upshifting?? Could this be a transmission issue at all? The transmission is automatic.

Tried to catch the lights on an OBD2 but didn't manage to as it wanted an engine restart (sorry this is the first time I have done anything with cars like this!). And as mentioned before the lights, jerking and intermittent grinding noise go away after restart of engine...

Little bit stuck at this point, as I've had the inlet manifold and dpf cleaned out, I've swapped the exhaust sensor, turbo valve seems to operate. What else could this be???

Thanks Alex.

 

Ahhh that's very disappointing, but thank you for sharing. I have an OBD2 sensor that bought online time ago that records most of the car sensor and you can later display them in a graph. I can compare the commanded instructions versus the actual positions. I will speak to a couple of mechanics and see if they have any ideas. I don't think I am going to go through the dpf cleaning yet because when I go over 3000 reps the car delivers the power as it should, and that means the engine is not fully clogged. I will let you know this week if I can make some progress with mine.