Stop/Start Mechanism initiating in middle of driving and causing a System Fault

ICE, Equipment, Options
boriskaz@gmail.com
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Qashqai Model: Mk.2 Qashqai - J11 (2013–2017)

Post by boriskaz@gmail.com »

Nissan Qashqai 2014 Tekna 1.6 DCI, 130 HP
We bought a 2014 Qashqai in October 2019 and about 6 months into owning the car the Stop/Start Mechanism showed a system fault in the middle of driving, usually on the motorway and mostly going uphill and faster. The only way to resolve at such times was to slowly roll to the side, as it was now in emergency mode with reduced revs etc… and then switch the car off and then switch it on again after a few minutes. The system seemed to be able to reset itself and if the driving subsequently was slow and without too many hills it could be kept under control. After parking all night and starting to drive just in the city here and there this never happens!
There is definitely a correlation to the car driving a lot, or uphill and fast on a longer drive to this happening, however I fail to be able to connect it to a Stop/Start System Fault and clicking into some sort of emergency mode. This has been ongoing and no one could ever resolve it (even a Nissan Garage). We are now considering to sell the card due to our lack of trust in this happening when on a longer trip.
I have consulted a mechanic who thinks it must be either an ECU failure or some of the wiring. He stated bench test the ECU and if that’s not it start with ohm testing the wiring for the Stop/Start.
As we have been struggling with this for almost 1.5 years now I am looking for some assurance as to the cause of this as I have gone around in full circle.

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gloucester
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Post by gloucester »

Welcome to this forum.

Stop/Start issues are often down to the battery needing replacement - there was also a faulty batch of batteries around that time but they should all have been replaced by now.

However I don't recall others on here reporting your particular combination of circumstances. Anyone?
(2015 Nissan Qashqai Tekna DIG-T 1.2 sold 15/6/18) ~ 2018 Suzuki Ignis SZ5 - 2018 Yamaha MT-07 ~ (2024 Volvo EX30 ordered)
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Qashqai Model: Mk.2 Qashqai - J11 (2013–2017)

Post by boriskaz@gmail.com »

Thanks for your reply...we have switched the battery already as this was the sort of 'go-to' solution of the Nissan Garage, but the problem continued with the brand new battery. We have tried pretty much everything I read about, but the Start/Stop Mechanism starting at 120 KMH on a highway and then showing a Start/Stop System fault which puts the car into an emergency mechanism, where once we switch the car off and on again the fault has disappeared is unusual. The last mechnic opinion I had was that there must be an electrical fault of soem kind either the ECU or wiring of the Stop/Start, but I am unsure how to even adress this.
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calnorth
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Post by calnorth »

Start/Stop faults are commonly flagged by:

Bad Battery
Emissions out of spec
Fuelling

When the ECU cannot control the engine correctly then a limp home mode can arise. Sensor problems often likely.

A specific speed is somewhat suspicious...only around that speed? Engine speed and increased effort (on incline).

Out of the three faults above I think I'd look at emissions...the exhaust. And particularly on an older diesel. Its possible that a fault, or combination, occurs in the exhaust system due to heat/gas pressure for instance...at 120kph (60mph) pressure is high and its very hot down there. Various sensors feeding the ECU are placed there.

There should be error codes (DTCs) that the Nissan garage should have seen. Without them its mainly guesswork.

ECU testing is rather substantial (alarming) and impractical without evidence of a fault specifically identified. Nissans CONSULT tool should have identified most errors under static test. Dynamically (vehicle at speed), certain sensors could be failing which CONSULT can't identify. The ECU should have recorded such errors though?
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Post by boriskaz@gmail.com »

Thanks so much for your help and reply. It is not a specific speed at which time it happens, but driving faster than usual normally on a motorway (I am sorry i may have mis-lead you with the 120 KMH...this was just to make the point of faster speed and driving for a while and usually uphill) - so what you called LOAD. Unfortunatley no error codes indicated anything usefull to the Nissan guys. They stated at one stage that it is the senbsor of the gas peddle - and we changed the whole peddle - and the problem appeared again. I have suspected for a while due to the bahaviour that this must be connected to maybe the DTF filter, or the O2 sensor and sensor pipe (some say that this can be packed with soot and needs cleaning or switching).

I personally failed with my knowledge to connect between a Stop/Start System fault and the above mentioned, so have not pursued yet as I wanted soem opinions...

I canot belive that this has hampered our driving the car for such a long time and noone has managed to resolve. I feel seriously disappointed that not even Nissan can figure this out and we are close to selling the car due to this issue, which we do not want to, but it makes the car totally unbreliable.

Thanks
malvern_man
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Post by malvern_man »

I've got no idea about your problem but it's not a good idea to use your email address as your user name, once the spam bots get hold of it your inbox will be inundated.
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calnorth
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Post by calnorth »

Diesel engine issues on this site commonly come up with exhaust gas sensing and DPF problems. Periodic engine load increase seems significant as regards performance drop from what you say.

Fuelling is of course the other end of the problem which I assume caused Nissan to change the throttle pedal positional sensing.

DTCs should be detectable for most exhaust problems (sensors + DPF) and are listed in Nissan Diagnostics procedure. Nissan use their special test and diagnostic tool (CONSULT) which should help them to identify performance problems.

Can I assume that your engine has passed annual emissions tests. In UK we have to pass an annual test (MOT)...vehicle integrity/safety/emissions and so on. This test is fairly severe. I'd expect to see failures in performance at those tests.

The attached picture is the Nissan R9M engine which might be yours. It shows the complexity of the system. Its guess work without DTCs and adequate test equipment:

https://www.engine-specs.net/renault/r9m.html
........

Scree15.png

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Post by boriskaz@gmail.com »

Thanks so much for your amazing help and suggestions.

I did pass my MOT equivilant here in Portugal without any issues and they did test the exhaust output. We have reviewed the DTC's many times but this gave noone any indication as to where this fault could be coming from. I am going to look for a Nissan Mechanic with a CONSULT Diagnostic Tool to see if this points us further.

The performance drop when this System Fault happens is due to the emergency mode the car switches into which is what others call the 'limping' mode whereas the system prevents the car to continue and limits the ability to drive down to just being able to stop soemwhere on the side. I then switch the car off and back on and the emergency mode is gone and the car drives normally again, however can repeat this with load many times over and over again. If we when this happened and switched the car off and then on again to eliminate the limp mode - we drive really slowly and not uphill and stay under about 100 KMH and drive carefully and slow...it may not happen again. Once we stop the car and then start driving again the next day - it is as if this never happened - untill we are again driving a distance and it could then happen again after even a week has gone by.

Something definitley triggers this Stop/Start System fault and it looks connected to load soemhow, which could be DPF Fildter or O2 Sensor as mentioned by soem of you above. Will have another go at this with DTC's and a CONSULT Tool. Is there anything I can check in the interim regarding the O2 sensor and O2 sensor pipe and the DPF Filter in terms of maintenanace...?
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calnorth
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Post by calnorth »

The ECU is certainly being triggered into its protection modes. Almost like a switch? NISSAN local should have the CONSULT tool which is the only test/diagnostic tool capable. They also may be aware of this particular fault? CONSULT should detect DTCs and also procedurally test various items

You can only check the wiring integrity...plug/socket connections to the exhaust related sensors. Something like WD40 spray onto the pins/sockets. Contact integrity.

R9M Engine diagnostic document attached showing most DTCs etc. Its not the latest:
.........
EC9_Diesel+-+ENGINE+CONTROL+SYSTEM+(R9M).pdf
(2.82 MiB) Downloaded 74 times
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Post by boriskaz@gmail.com »

Quick update: The Consult Tool gave us again the indication that soemthing is faulty with the accelerator pedal. This is the fault which was already invetigated 3 times around and once a sensor was switched by Nissan and the ECU was reste and just 3 months ago we changed the whole pedal to a brand new one - but the problem keeps popping up.

So the mechanic called an expeienced electrician, who stated that in his view it has nothing to do with the actual accelerator pedal, but he thinks there must be an electrical short soemwhere in the wiring causing the ECU to switch into 'limp-mode'. He stated that best to go to the main fuse box inside the engine compartment and starting to check fuses and wiring for soem sort of a short, causing the car to go into a Start/Stop Sytem fault. We shall also focus as suggested on the exhaust related sensors, combined with Start/Stop sensors and anything coming from the accelerator pedal....

The car needs ot go in for 2 days so the mechnic has enough time to trace and try and hopefully we shall find the cul[prit soemwhere. Will keep everyone updated.
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