Auto Transmission Question(s)

2006_FrontierLE said:

The issue is that it is not harsh... almost drags or delays engaging 2nd gear. The only what to explain it is if you were driving a manual transmission and were shifting from 1st to 2nd and depressed the clutch slowly... The RPMs would remain steady but the clutch would engage slowly.

I have also noticed that my MPG has gone from a very consistent 18.5 to 17 mpg. But that may be related to the colder weather.


Thanks, I may try resetting the computer.

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Hi Frontier LE,
My '06 has been doing something very similar for the past seven months or so. It first really became noticeable last August around 35K; the truck has never been abused, towed with or hauled over 400lbs. It seemed sluggish in general but the more I paid attention it seemed to be a result of being very slow to shift, exactly like you said being slow with clutching and shifting, primarily 1-2 but to a lesser extent 2-3 also. 3-4 and 4-5 are just like new and seamless. Also found that when slowing down from 40 or so to 20-25 and then accelerating again as you would in traffic, it felt like it was between gears and would finally engage harshly. But, when shifted manually it appeared to shift quickly and normally. Also, like you I found that gas mileage had dropped easily a few points.

I did a drain and fill with Matic-S and really found no difference. Made an appointment with the dealer and they said there were no stored codes and no SES light so there were no problems, "nothing's wrong, just drive it." But why did it change so noticeably after 3+ years?

I reviewed the FSM and thought that maybe it was something "learned" that needed to be erased. Nissan states that the battery must be disconnected for 24hours to fully clear any learned habits in the ECU. I tried that over Thanksgiving and while there was a slight difference in performance it really wasn't any better.

I stopped by the dealer again and asked if there was a chance that the ECU wasn't fully erased by disconnecting the battery, they said no that would have done it and any learned habits were cleared and it should be like new. They did a check for TSB's and said there was nothing and that the one for 08's and reflashing the computer only applied to 08's with a specific issue and they wouldn't do it to mine. I did get to drive an '08 with 40K+ on it and it seemed "normal" to me; but the dealer still said mine was fine and to just drive it.

So recently, colin123 posted a link on how to reset the ECU and recalibrate the accelerator and throttle position w/o disconnecting the battery, How to:ECU Reset,Throttle & Accelerator Position Learning - Nissan Titan Forum. This link stated that there is really no way to know how much data is erased and how quickly by disconnecting the battery and that to fully erase the data and recalibrate everything the proper procedure should be followed. I gave it a try and it did make a notable improvement. Truck was very peppy again and the shifts were quicker and smoother. With the very slightest of pressure on the accelerator you could feel the power build and you would move right out almost like new; the past seven months it was nothing like this. But, after a week and a half of driving the shifts were getting sluggish and delayed again. I just went through the procedure again last night and everything is good again but for how long?

I'm not sure what's going on. If it's learned response, why did it take three years to show up the first time? I'm wondering if something is malfunctioning and the computer is compensating for it?