2012 sputtering on incline

[Tigergrad98]

Just joined the board and have already read some posts about similar issues. My wife’s 2012QX56 with 141k miles has been sputtering when going up inclines and occasionally on flat surfaces. First step was taking it to the dealer and they couldn’t pull a code or diagnose. Went to a local shop that focuses on Infiniti and they checked everything and narrowed it to the torque converter and referred me back to the dealer. Dealer used their diagnosis and data and said they’d have to replace the entire transmission. Got a second opinion from a trusted transmission shop in town and he wasn’t sure it was the torque converter. He said he’s happy to replace the transmission but was worried that wouldn’t fix the issue. No codes are pulling and no one seems to have a clue what’s causing it. Has anyone successfully solved a similar issue?

 

[marctronixx]

even if the tranny was acting up, there woudl be some codes. are you sure your obd port is working? there is a fuse on it and if its blown, the obd port will not operate.

issues it could be due to your age and mileage:

coil packs, plugs
high pressure petrol pump
dirty MAF
o2 sensor(s)
cats (could be leaking at the flange where they connect to the pipe)
undiagnosed electrical fault
poor compression (have you had your compression checked?)
PCV

did you have the car since new? if you bought used, how long have you had it? any maintenance records on it if used?

what kind of fuel do you use? high test (premium) or lower octane?

do you use any kind of petrol injector products?

when at idle, what is the "resting" rpm? 800? higher than that? lower? does it idle rough?

any engine mods done to the car? has it passed smog before if thats requires in your area?

any blue smoke or any kind of smoke at cold startup?

there's gotta be a code ,based on your description.

 

[Tigergrad98]

even if the tranny was acting up, there woudl be some codes. are you sure your obd port is working? there is a fuse on it and if its blown, the obd port will not operate.

issues it could be due to your age and mileage:

coil packs, plugs
high pressure petrol pump
dirty MAF
o2 sensor(s)
cats (could be leaking at the flange where they connect to the pipe)
undiagnosed electrical fault
poor compression (have you had your compression checked?)
PCV

did you have the car since new? if you bought used, how long have you had it? any maintenance records on it if used?

what kind of fuel do you use? high test (premium) or lower octane?

do you use any kind of petrol injector products?

when at idle, what is the "resting" rpm? 800? higher than that? lower? does it idle rough?

any engine mods done to the car? has it passed smog before if thats requires in your area?

any blue smoke or any kind of smoke at cold startup?

there's gotta be a code ,based on your description.

Thanks for the response and great questions. I will admit that my knowledge of technical issues is limited. I 100% agree that it should be throwing a code so checking the fuse for he obd port is a great suggestion. The local import shop checked most of what you listed out...coil packs and plugs (all new plugs), the cat was tested and cleaned. I bought the car CPO from the Infiniti dealership here. Sadly the warranty has expired. I only have the records from when we've owned it and we've taken care of all maintenance as suggested by the dealer.

We only use premium fuel. No petrol injector products. No mods to engine. No smoke of any kind and smog is not required here in SC.

 

[marctronixx]

i didnt know one can "clean" a cat, but im not a mechanic. i just thought they would be replaced.

they checked the coil packs but did they replace them? @140K miles they are probably due for replacement.

id look at the fuel pump, do a compression test, change the coil packs, clean the MAF, double check the 02 sensors and cats.

id check carfax and see any history on the car. also verify to make sure the timing chain recall was done as well.

______________________________

 

[Tigergrad98]

i didnt know one can "clean" a cat, but im not a mechanic. i just thought they would be replaced.

they checked the coil packs but did they replace them? @140K miles they are probably due for replacement.

id look at the fuel pump, do a compression test, change the coil packs, clean the MAF, double check the 02 sensors and cats.

id check carfax and see any history on the car. also verify to make sure the timing chain recall was done as well.

Thanks. I could be off on cleaning them...could have been something else. Appreciate your feedback.