faulty barometer?.. ECU change = different behaviour

While I was driving my almost new 2017 CX9, when it suddenly started to do all sort of strange things and all the lights started to light up, immediately I went to the distributor ( service) and they detected that the fault was the barometer which was giving abnormal figures.
the barometer is inside the ECU so the whole ecu had to been changed. the warranty was immediately executed and changed as soon as the part was available. the distributors service was good and fast.
after the change of the part the Cx9 has been working normal and I feel confident that it will not happen again , the strange thing is that immediately I noticed a different behavior of the car.

a) usually the CX9 had a lot of torque steer while pressing the accelerator to the top from a low speed ( first gear or second) suddenly this was not felt any more.
b) the steering wheel feels a bit tighter and more precise.

My first feeling was that once they changed the ECU the cx9 was slower than before but I guess its just a feeling due to the lack of torque steer, so it might just feel less dramatic, but there is a change there, has anyone had this kind of situation? the new ECUS have a different setting? does this has something to do with g vectoring?
any ideas or comments?

Gatuno said:

While I was driving my almost new 2017 CX9, when it suddenly started to do all sort of strange things and all the lights started to light up,...

Click to expand...

Ok, at this point I'm thinking, hmmmm. Poltergeist?

Gatuno said:

...immediately I went to the distributor ( service) and they detected that the fault was the barometer which was giving abnormal figures.

Click to expand...

Did you notice any prompts under Applications > Vehicle Status > Warnings? Whether there were any DTCs or not, I always pull codes using my own OBDII scanner just as sanity check if anything abnormal comes up relative to vehicle function or behavior. A basic scanner is inexpensive and can help you focus a mechanic (if you do the initial legwork) to prevent parts swapping instead of professional troubleshooting.

Gatuno said:

...the barometer is inside the ECU so the whole ecu had to been changed. the warranty was immediately executed and changed as soon as the part was available. the distributors service was good and fast. after the change of the part the Cx9 has been working normal and I feel confident that it will not happen again , the strange thing is that immediately I noticed a different behavior of the car.

a) usually the CX9 had a lot of torque steer while pressing the accelerator to the top from a low speed ( first gear or second) suddenly this was not felt any more.
b) the steering wheel feels a bit tighter and more precise.

Click to expand...

The ECU handles a lot of sub-functions relative to engine performance. Could have also been faulty ECU. With the replacement ECU, it is quite possible that you are now experiencing what is simply normal steering in the CX-9 as being "tighter steering" given the net effect of correct baro pressure input to the ECU resulting in correct (specified) power output of the engine (horsepower/torque/rpm). G-Vectoring was not the best name that Mazda could have used as it really has nothing to do with Torque Vectoring or G-Forces implicitly.

However, G-Vectoring (which is only one part of a complete set of iSKYACTIVE Vehicle Dynamics technologies) would indeed be correlated with the ECU among other dynamic vehicle components that would also provide input to the G-Vectoring algorithm. In an overly simplified explanation, G-Vectoring makes a subtle change in RPM as you enter corners in an effort to shift weight forward and to allow for greater stability through the corner as you exit - where torque is then restored. The typical driver won't notice anything but "tighter steering," whereas someone with high performance driving experience might notice a degree of better linear transfer of weight leading to a more balanced vehicle through the turns.

I guess RPM-Vectoring does not sound anywhere near as sexy as G-Vectoring. Or Dynamic RPM Vectoring, et-al.

Gatuno said:

While I was driving my almost new 2017 CX9, when it suddenly started to do all sort of strange things and all the lights started to light up,...

Click to expand...

Ok, at this point I'm thinking, hmmmm. Poltergeist?

Gatuno said:

...immediately I went to the distributor ( service) and they detected that the fault was the barometer which was giving abnormal figures.

Click to expand...

Did you notice any prompts under Applications > Vehicle Status > Warnings? Whether there were any DTCs or not, I always pull codes using my own OBDII scanner just as sanity check if anything abnormal comes up relative to vehicle function or behavior. A basic scanner is inexpensive and can help you focus a mechanic (if you do the initial legwork) to prevent parts swapping instead of professional troubleshooting.

Gatuno said:

...the barometer is inside the ECU so the whole ecu had to been changed. the warranty was immediately executed and changed as soon as the part was available. the distributors service was good and fast. after the change of the part the Cx9 has been working normal and I feel confident that it will not happen again , the strange thing is that immediately I noticed a different behavior of the car.

a) usually the CX9 had a lot of torque steer while pressing the accelerator to the top from a low speed ( first gear or second) suddenly this was not felt any more.
b) the steering wheel feels a bit tighter and more precise.

Click to expand...

The ECU handles a lot of sub-functions relative to engine performance. Could have also been faulty ECU. With the replacement ECU, it is quite possible that you are now experiencing what is simply normal steering in the CX-9 as being "tighter steering" given the net effect of correct baro pressure input to the ECU resulting in correct (specified) power output of the engine (horsepower/torque/rpm). G-Vectoring was not the best name that Mazda could have used as it really has nothing to do with Torque Vectoring or G-Forces implicitly.

However, G-Vectoring (which is only one part of a complete set of iSKYACTIVE Vehicle Dynamics technologies) would indeed be correlated with the ECU among other dynamic vehicle components that would also provide input to the G-Vectoring algorithm. In an overly simplified explanation, G-Vectoring makes a subtle change in RPM as you enter corners in an effort to shift weight forward and to allow for greater stability through the corner as you exit - where torque is then restored. The typical driver won't notice anything but "tighter steering," whereas someone with high performance driving experience might notice a degree of better linear transfer of weight leading to a more balanced vehicle through the turns.

I guess RPM-Vectoring does not sound anywhere near as sexy as G-Vectoring. Or Dynamic RPM Vectoring, et-al.

Glad you got it fixed. Still puzzled as to why it needed to be fixed on a relatively brand new CX-9, though. That bothers me just a little. I hope we don't start seeing more of this in the 2018 line.

CJ4 said:

Ok, at this point I'm thinking, hmmmm. Poltergeist?





Did you notice any prompts under Applications > Vehicle Status > Warnings? Whether there were any DTCs or not, I always pull codes using my own OBDII scanner just as sanity check if anything abnormal comes up relative to vehicle function or behavior. A basic scanner is inexpensive and can help you focus a mechanic (if you do the initial legwork) to prevent parts swapping instead of professional troubleshooting.




The ECU handles a lot of sub-functions relative to engine performance. Could have also been faulty ECU. With the replacement ECU, it is quite possible that you are now experiencing what is simply normal steering in the CX-9 as being "tighter steering" given the net effect of correct baro pressure input to the ECU resulting in correct (specified) power output of the engine (horsepower/torque/rpm). G-Vectoring was not the best name that Mazda could have used as it really has nothing to do with Torque Vectoring or G-Forces implicitly.

However, G-Vectoring (which is only one part of a complete set of iSKYACTIVE Vehicle Dynamics technologies) would indeed be correlated with the ECU among other dynamic vehicle components that would also provide input to the G-Vectoring algorithm. In an overly simplified explanation, G-Vectoring makes a subtle change in RPM as you enter corners in an effort to shift weight forward and to allow for greater stability through the corner as you exit - where torque is then restored. The typical driver won't notice anything but "tighter steering," whereas someone with high performance driving experience might notice a degree of better linear transfer of weight leading to a more balanced vehicle through the turns.

I guess RPM-Vectoring does not sound anywhere near as sexy as G-Vectoring. Or Dynamic RPM Vectoring, et-al.

Click to expand...

hey CJ,
always ready for a response from you .. and for sure next time ( hope never comes ) ill ask about the codes

yes, at first I though " poltergeist "

To your question of which warnings, ... all of the telemetric warnings lit up, abs, front anti impact, rear, lane warning, etc etc etc all of them at the same time so u can imagine it looked like an over worked Christmas tree . At that moment I just drove to a safe place to stop and turned the car off, a minute later I turned it on and everything worked properly , by the way, the ac compressor also stopped working and worked perfectly after the turn off/on thing.

it seems like the old ecu was faulty as u say cause there is a lot of differences while I'm driving, non of them bad differences.

By the way, I'm always learning with your answers, I guess ill just keep asking hehe

just read ur last sentence


"Glad you got it fixed. Still puzzled as to why it needed to be fixed on a relatively brand new CX-9, though. That bothers me just a little. I hope we don't start seeing more of this in the 2018 line. "

Yeah I guess all cars have different kinds of problems, and these wont ever stop, I guess mazda has found a good way to deal with them and its fast action and problem solving. When things are fixed in a fast way the problem ends as a good thing cause u ll have a satisfied costumer that will build up loyalty to the brand and not only the product.

Gatuno said:

just read ur last sentence


"Glad you got it fixed. Still puzzled as to why it needed to be fixed on a relatively brand new CX-9, though. That bothers me just a little. I hope we don't start seeing more of this in the 2018 line. "

Yeah I guess all cars have different kinds of problems, and these wont ever stop, I guess mazda has found a good way to deal with them and its fast action and problem solving. When things are fixed in a fast way the problem ends as a good thing cause u ll have a satisfied costumer that will build up loyalty to the brand and not only the product.

Click to expand...

Yep. Mass produced anything will always have a margin of error - especially with electronics. I guess the only fight that can be put up against that is making sure you are using a solid supplier for components you don't build in-house. I'm actually happy to hear that there were warning signs prior to the failure or in conjunction with the failure. The christimas tree effect being at least one of them. It looks like you probably had a lot of DTCs anyway and yes, the AC Comp would no doubt be affected by a failing ECM/ECU - more than likely indicating some kind of voltage problem affecting its clutch, relay, etc - down the rabbit hole.

With more and more being run through the on-board ECM/ECU these days, it becomes even more important to have solid computer designs and equally solid suppliers. As an old design engineer (from a different industry), I see composite ECM and ECU architecture in the future. It just makes sense. A PnP ECM/ECU design would allow for LRU (Line Replaceable Unit) type implementation. That way, when/of something goes sideways, you would simply unplug the Sub-ECM component and replace it, instead of the entire computer. Of course, I'm a design engineer - so I'm free to have these kinds of 'wet' dreams - in fact, its my job to dream outside the box.

Glad all worked out for ya!