Slow Transmission Response

[Shinobot]

Went for a drive today, it has been fairly cold and there's still some lingering snow and ice in the area but no recent precipitation and my QX70 was pretty much cleared off of snow/ice. All seemed normal, but I noticed when I went to goose the throttle one time it felt uncharacteristically slow and laggy and basically didn't do much. I wrote it off that perhaps it was not at full operating temp though never noticed anything like this any other time.

On expressway later once it was warmed up I got on the gas pretty good and it's like you could count out 1...2...3...as it was shifting from the higher gear, to the next lower, to the next lower and then when maintaining that throttle position the speedometer was going faster but felt like driving a significantly slower and less powerful vehicle. Almost like someone stuffed something in the air intakes so it couldn't breathe. I genuinely wondered if somehow there was snow or ice blocking an air intake that I missed but the front of the car had no visible snow on it any longer so I was doubtful but only thing I could think of.

I got to my destination and tried to rev it, and it seemed fully responsive in Park. Turned it off and then restarted it after a minute or so, all seemed totally fine again when revving. Put it in gear, now it feels responsive again. Get on the expressway again, acceleration feels completely back to normal. I had no check engine lights or anything else come on.

A few hundred miles ago I had my local Infiniti dealer perform the transmission flush and put the new fluid in (this done at just under 131k miles which per their recommendation was still fine to do). My dad has a G37xS and told me one time his did something weird like this once in the several years he owned it but it never did it again and has since never had a similar issue. In his case, he did not have the transmission fluid changed at the time.

Has anyone experienced this to speak more to what the cause is? It drove fine maintaining the speed on the highway, and it felt not nearly as laggy at low speeds but it was absolutely shifting in the higher gears no problem and if I put it in Drive Sport or manual mode was doing those fine as well just much slower than usual.

 

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Sounds like something wasn't quite where it needed to be and the car decided to play it safe even after being warmed up. This tends to happen if a temporary condition is detected and the car responds by going into somewhat of a "safe mode" but lets you drive it anyways. Usually by restarting the car it should clear itself. Sometimes you need to drive a bit before restarting for it to clear.

The only other thing that sounds similar to this would be enabling the snow mode switch located just below the gear shifter. Not saying that's what happened here just that it feels like it. I can't see the car enabling this mode on it's own but the programming does reside in the ECU so it's possible it enabled the same programming as a result of something.

Sometimes weird things happen as a result of something insignificant but when the right circumstances occur, a scenario presents itself. Infiniti has pretty good programming when it comes to dealing with variations in operating conditions. There's a level that it will accept and work around without throwing a code and then there's scenarios where it will throw a temporary code (light) and then ones where they are sever enough to throw a permanent code. In your case it didn't throw a code.

I know that for these cars they work within a certain tolerance but are really good at dealing outside of them. When that tolerance gets exceeded they start to exhibit varying levels of conditions. For example, if the throttle bodies are dirty enough, that will cause harder shifts, poorer idle control, etc. If the MAF sensors are dirty enough, air/fuel mixing will get thrown off, engine will idle more rough, harder shifting, etc. Sure the ECU has an array of sensors for validating other sensors including default parameters to ensure ideal operating parameters but the ECU has a way to compensate with small drawbacks in performance until it becomes more noticeable and eventually throws a code to get it serviced.

But overall I think it was either particularly cold this time, maybe humid cold, possibly some liquid or debris touched a sensor the wrong way and it simply put it in safe mode.

The fact that it did it once and hasn't happened since means the transmission is okay otherwise you'd be seeing this more often.

For cold environments I usually let the car warm itself at least a quarter way on the temp scale before driving. Increases engine lifespan and lessens fuel blowby into the oil pan.

With these transmissions I know the manual says that they are a sealed system and the oil lasts the lifetime of the transmission...which is a bunch of nonsense...the actual manufacturer of these transmissions states to replace the oil every 55K miles. I've flushed and refilled the transmission twice already. During my initial flush around 60K miles I noticed the oil was closer to brown than red which means the oil was deteriorated. The second time around I changed it sooner where it was a dark red around 50k miles. Ideally you want to beat it to the punch. Oil is always cheaper than a new transmission. These newer high efficiency/high performance transmissions are designed in a way that causes oil to burn faster and to keep them running longer, oil has to be changed more often. I personally use Motul for my oil as I find it to be of higher quality and the transmission seems to run smoother. If you find that your transmission is starting to experience hard shifts or random jerks..it's either the oil needs replacing or the MAF sensors/throttle bodies need cleaning.

Hope that helps and let us know if run into it again!

Cheers!

 

[Shinobot]

Sounds like something wasn't quite where it needed to be and the car decided to play it safe even after being warmed up. This tends to happen if a temporary condition is detected and the car responds by going into somewhat of a "safe mode" but lets you drive it anyways. Usually by restarting the car it should clear itself. Sometimes you need to drive a bit before restarting for it to clear.

The only other thing that sounds similar to this would be enabling the snow mode switch located just below the gear shifter. Not saying that's what happened here just that it feels like it. I can't see the car enabling this mode on it's own but the programming does reside in the ECU so it's possible it enabled the same programming as a result of something.

Sometimes weird things happen as a result of something insignificant but when the right circumstances occur, a scenario presents itself. Infiniti has pretty good programming when it comes to dealing with variations in operating conditions. There's a level that it will accept and work around without throwing a code and then there's scenarios where it will throw a temporary code (light) and then ones where they are sever enough to throw a permanent code. In your case it didn't throw a code.

I know that for these cars they work within a certain tolerance but are really good at dealing outside of them. When that tolerance gets exceeded they start to exhibit varying levels of conditions. For example, if the throttle bodies are dirty enough, that will cause harder shifts, poorer idle control, etc. If the MAF sensors are dirty enough, air/fuel mixing will get thrown off, engine will idle more rough, harder shifting, etc. Sure the ECU has an array of sensors for validating other sensors including default parameters to ensure ideal operating parameters but the ECU has a way to compensate with small drawbacks in performance until it becomes more noticeable and eventually throws a code to get it serviced.

But overall I think it was either particularly cold this time, maybe humid cold, possibly some liquid or debris touched a sensor the wrong way and it simply put it in safe mode.

The fact that it did it once and hasn't happened since means the transmission is okay otherwise you'd be seeing this more often.

For cold environments I usually let the car warm itself at least a quarter way on the temp scale before driving. Increases engine lifespan and lessens fuel blowby into the oil pan.

With these transmissions I know the manual says that they are a sealed system and the oil lasts the lifetime of the transmission...which is a bunch of nonsense...the actual manufacturer of these transmissions states to replace the oil every 55K miles. I've flushed and refilled the transmission twice already. During my initial flush around 60K miles I noticed the oil was closer to brown than red which means the oil was deteriorated. The second time around I changed it sooner where it was a dark red around 50k miles. Ideally you want to beat it to the punch. Oil is always cheaper than a new transmission. These newer high efficiency/high performance transmissions are designed in a way that causes oil to burn faster and to keep them running longer, oil has to be changed more often. I personally use Motul for my oil as I find it to be of higher quality and the transmission seems to run smoother. If you find that your transmission is starting to experience hard shifts or random jerks..it's either the oil needs replacing or the MAF sensors/throttle bodies need cleaning.

Hope that helps and let us know if run into it again!

Cheers!

Thank you for the detailed response! I thought so too about the snow mode, it was definitely off. I toggled it on and tried the same and then back off to see if it made any difference but did not seem to change anything. I wonder if the slight spin in my driveway it did on the snow/ice freaked out the traction control or some other system to cause it, but it definitely ran fine other than the laggy response.

Will definitely let it warm up a little more next time. My dad's G37 has had more issues, I think owing to it having 4 or 5 previous owners to my QX70's one owner (who also was proactive enough to have done the differential fluid changes as well). Besides this fluke, it has been fine though I have only put maybe 400-500 miles on the car since I've bought it. Will continue to monitor if I ever see it happen again, the car was well maintained every way that I can tell and the PPI from the Infiniti dealer only revealed leaking valve cover gaskets and that it was due for transmission fluid change and otherwise said the vehicle was in great shape so I felt reassured in my purchase. I saw another QX70 locally with 260k+ miles that despite some physical wear didn't have any check engine lights on in the dealer pictures, so I'm wishful for a similar result in mine

 

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Glad I could help! It's good to see people taking car of their vehicles! I know people who literally do nothing in terms of maintenance and then blame the manufacturer when something breaks lol.

These Infiniti's are pretty well built and they've come a long way from what they used to be. I know they have their own issues but sometimes it's a result of something being overlooked or poor maintenance or a factory flaw that does tend to happen. Hopefully the issues your G37 experienced weren't too bad and easily fixable.

When I purchased my Infiniti as the second owner, I replaced all the fluids on it just to reset everything. I've learned it's cheaper to know what you have in it rather than finding out someone put the wrong fluid resulting in a component failure. That includes brake, engine, transmission, differential, transfer case and power steering oils and coolant. The only fluid I use from the dealership is the blue coolant. Otherwise everything else is Motul.

As long as you keep the maintenance up and keep it washed, it'll last a long time!