2014 QX70 sluggish throttle response

A forum for lovers of Infiniti's hot-rod crossover, the FX! In 2014, all FX models will be named Infiniti QX70, in line with Infiniti's new naming structure.
xmal
Posts: 3
Joined: Tue Jan 02, 2018 12:58 pm
Car: QX70 30d

2014 QX70 sluggish throttle response

Postby xmal » Tue Jan 02, 2018 1:29 pm

Hello Everyone, Hope someone here can help. I have a UK 2014 QX70 3.0l diesel. Most of the readers seem to be US owners, but anyone please chip in with a problem I am having with my UK diesel version. Firstly, when I got the car it was great- the diesel produces 550Nm torque and every gear had instant power. However after a few months acceleration in the 50-70mph range fell flat. I would have to floor the accelerator pedal (instead of a light touch and instant power), and I would get a wall of power about 2-3 seconds after that. The lower 1-3 gears in slower speeds seem to be fine. I brought this up with the Infiniti Dealer and they indicated that it might be the "intelligent" throttling system they have that learns a driver's style. Not sure if it is this or if they are trying to fob me off. I did a little searching and it seems very similar to the post for the G35 and G37:
howto-reset-ecu-learned-behavior-m37-m5 ... 03469.html

I tried this procedure on the QX70, but it did not seem to work. I would like to try an ECU reset without having to disconnect the battery. Does anyone know how to do this on my motor or does anyone have something similar that they have experienced and had a fix?

Also if I get the ECU reflashed will this "learned behaviour" also return to the flashed ECU or does the flashing completely remove this "learned behaviour"?

Thanks in advance, xmal


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centralcoaster33
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Re: 2014 QX70 sluggish throttle response

Postby centralcoaster33 » Tue Jan 02, 2018 2:04 pm

Welcome to NICO Club!

I hope someone can help you. I've only heard of diesel, never tried it myself.

As far as relearns and resets, yeah, don't pull your battery cable, it's resetting everything. There are relearn procedures and those are typically discussed in the EC chapter, though they may be referenced there and live in another chapter.

A reflash will re-write the base software is my understanding. You'd still have to perform the relearn steps to get that dialed in I think.

We do have a FSM for the vehicle and it perhaps discusses different fuel options. Take a look there.
http://www.nicoclub.com/FSM/QX70/2014%20QX70/

xmal
Posts: 3
Joined: Tue Jan 02, 2018 12:58 pm
Car: QX70 30d

Re: 2014 QX70 sluggish throttle response

Postby xmal » Tue Jan 02, 2018 3:45 pm

centralcoaster33 wrote:
Tue Jan 02, 2018 2:04 pm
Welcome to NICO Club!

I hope someone can help you. I've only heard of diesel, never tried it myself.

As far as relearns and resets, yeah, don't pull your battery cable, it's resetting everything. There are relearn procedures and those are typically discussed in the EC chapter, though they may be referenced there and live in another chapter.

A reflash will re-write the base software is my understanding. You'd still have to perform the relearn steps to get that dialed in I think.

We do have a FSM for the vehicle and it perhaps discusses different fuel options. Take a look there.
http://www.nicoclub.com/FSM/QX70/2014%20QX70/
Thank you Central Coaster for your help. I do not have any option with diesel fuel. Diesel is diesel, only the one type here in the UK, unlike gasoline that comes in different grades. I have had a look at the EC Chapter and I can not see any relearn procedure like there was for the G37s... Thank you for the heads up for not to disconnect the battery.
If anyone has done a ECU relearn procedure for a QX70 (US FX35) I would greatly appreciate a heads up on how to do it.

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Re: 2014 QX70 sluggish throttle response

Postby EdBwoy » Sun Jan 07, 2018 11:57 pm

In my experience a reflash will just bring the car back to base behavior. Admittedly, on newer cars, I have only had it done it on the transmission rather than the ECU. To me it seems like this could be a transmission programming issue.
IT doesn't mess the car up, it's just that if you drove like a boy racer, it might take a few drive cycles for you to feel like the car is in sync with you again.

Well, it depends... When you floor it, does the RPM change to indicate that the transmission is in another gear... just with a delay in getting the car to move? If yes, then it's engine management. If no, then the transmission isn't quite getting the message that you are in need of a change in gears.

What I would do is ask the dealer if any TSBs (technical service bulletin) exist for your car. Whether they exist or not, I would ask for a quote to reflash/ reprogram the transmission then engine.

I understand your frustration, and I hope we make some headway in this soon.

xmal
Posts: 3
Joined: Tue Jan 02, 2018 12:58 pm
Car: QX70 30d

Re: 2014 QX70 sluggish throttle response

Postby xmal » Sat Jan 13, 2018 3:30 am

Just a quick update to the problem. I took the QX70 into my local Infiniti Dealer and it reported a C1109 (battery Voltage) fault and also a P1585 G Sensor fault. The engineer reset the P1585 fault and I immediately noticed a marked improvement in performance and gear changing response. We are going to monitor the situation to see if the part needs replacing...

EdBwoy
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Re: 2014 QX70 sluggish throttle response

Postby EdBwoy » Sat Jan 13, 2018 5:24 pm

Those are definitely codes that needed someone with the correct diagnostic tools. Thanks for reporting the progress so far.

Crazy. I knew the existence of the yaw sensors and how they interacted with the ABS/VDC system, but this is new. I suppose I shouldn't be surprised considering how smart these transmissions are.


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