Inconsistent driveability

Tiny
TECHTWOU
  • MEMBER
  • 2015 INFINITI Q70
  • 3.7L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 37,000 MILES
Day to day driving is inconsistent, the car response is sluggish, acceleration very slow to the point that I have to go to wot to get the car to respond. Standard mode is more responsive than sport mode. So far the throttle body has been checked, the air filters, the ECM software has been updated and reset. Transmission shifts erratically yet the dealer states that this is the norm, harsh up-shifts and downshifts.
Friday, June 15th, 2018 AT 12:17 PM

3 Replies

Tiny
STEVE W.
  • MECHANIC
  • 15,237 POSTS
Being it should still be under the factory warranty I would take it to a different dealer and get at least a second opinion.

With the shifting issues and poor acceleration I would start by checking the brake switch and its circuit as both of those can be caused by a bad or maladjusted brake switch.

There is a TSB on the switch:

Infiniti; diagnosis of poor acceleration or lack of power

Applied vehicles: All Infiniti vehicles with electronic throttle control

Service information:

If a customer describes lack of power or poor acceleration, perform the following checks before attempting any repair:

Check for stored DTCs.
Check if the driver is resting their left foot on the brake pedal while accelerating. Advise the customer not to rest their foot on the brake while accelerating.
Use Consult-III plus in Engine Data Monitor to check operation of the brake lamp circuit signal. Monitor the brake switch during the incident; it should be "off".

Causes of brake switch "on":

Brake switch incorrectly adjusted (switch is adjusted "on" when it should be "off").
Damaged brake lamp wiring/circuit (damage causes signal to ECU to show "on" when it should be "off").

Might be worth it to look at it at least.
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Friday, June 15th, 2018 AT 1:52 PM
Tiny
TECHTWOU
  • MEMBER
  • 2 POSTS
Yes, I did take it to another dealer. The dealer I purchased the vehicle from did not even address the issue just stated that is how it suppose to drive the other dealer reset the ECM and updated the software, but both dealers drove the vehicle and stated "That is how it suppose to drive" and with no codes stored they cannot find anything wrong with it. I suggested driving another vehicle on the lot as a comparison, but they did not, with only two Infiniti dealers in the area, can a Nissan dealer work on the vehicle?
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Friday, June 15th, 2018 AT 2:08 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,237 POSTS
They can but sometimes will not. A scan tool would show if the switch was an issue. It could also be that they have it tuned as a luxury car and it does drive that way, have not driven one myself. You could just go and find another one and take it for a test drive to compare them. That might show if it is an actual problem and give you more to go on.
Being an AWD it will be different than a FWD only so try to find an AWD to compare it to.
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Friday, June 15th, 2018 AT 2:58 PM

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