Hi all.

I'm sure everybody is sick of seeing things like this crop up, but I've recently had a few issues with my 2018 2.2 awd 150 model CX-5 with around 97k on the clock. Prior to this it has run absolutely note perfect.

Over the last week or so it's been returning poor fuel economy (like it's been running a regen almost constantly), the power delivery has been less smooth than usual at low RPM's and it's been "surging" back and forth on very low throttle (going downhill, for example). It's also had a very intermittent misfire at idle that goes away with a blip of the throttle, or sorts itself out after a few seconds. It's never thrown smoke or ran rough other than the aforementioned issues though.

Thinking it may just need a regen and a good hard run (although it did one the other day at the usual 160-180 mile interval) I took it for a bit of a thrashing today, but midway through it went into what felt like reduced power (but not by much) and confronted me with SCBS malfunction (X2), DSC malfunction and parking brake malfunction on the onboard computer with lights on the dash. I drove it home and turned it off, left it a minute or so and switched it back on, only to find no warnings whatsoever.

It does mixed running, but always gets a good run or two each week. It gets used to tow fairly regularly, and has been run on as good quality diesel as I can find locally with Miller oils diesel power ecomax added to every tank. Serviced 2x a year, and barely dilutes the oil at all.

Does anybody have any similar experiences? Easy fix or a garage and a big bill job?

 

Check the engine for build up. That's what comes to mind. Usually the 2.2 engines have a lot of coolant issues too.

 

1st step is getting it scanned for codes.

 

Been to garage, checked on their scanner. No fault codes whatsoever and all live values well within normal range. Technician reckons it's one of the best ones he's seen, so still no closer to diagnosis.

 

If what you claimed is correct about the condition and drivability of your Mazda there will be information to be found in the ECU. My guess is they only did a basic "check for current DTCs" and did not explore the other important areas of the ECU. If there was more, they reported to you then it is helpful to try to tell us all they did?

 

Usually I'd agree with you, but I stood and watched while they had it hooked up. No codes and, as I say, all live values well within normal range. By all accounts the car is running every bit as well as it should be (on paper at least). The low MPG has gotten slightly better over the last few days, but it still hesitates/jerks on light throttle cruising and going downhill and the power delivery doesn't seem as smooth at low RPM. Garage confirmed what I've said the problem is as they've also felt it, but their scanner shows absolutely no issues so they've asked me to drive it until the fault codes appear again and take it straight back to them when/if they do.

 

Yes but there are 3 main area to look at and most service mechanics fail to look in the basic 3, only current DTC.
Because your engine is controlled by the ECU and the ECU get information from sensors then your power lower loss would be reported in the4 ECU unless the connection to the ECU is at fault (not likely from what you posted so far) or the ECU itself is failing.