So I have began to notice more and more in my driving, mostly highway, that at any speed, my rpm will differ drastically. I use cruise control always. But I'll notice that at the same speed my rpm can differ by ~2-400 rpm. Any body else notice this? I did try searching(but I do manage to screw that up occasionally), but couldn't find anything. But if I missed something please direct me
I've also wondered now if this could explain my mpg, I easily do 90% freeway driving(and stated previously I always use cruise) with speeds usually in 70-75 range, but have never even hit 21mpg.

 

More information would be useful ... Such as year , milage , and maintenance history....Any CEL or pending codes ?

 

If you are going uphill and downhill, could be the lock-up torque converter locking and unlocking as needed.

 

This.

 

'03, ~116k, no codes, maintenance up to snuff, maybe trans oil change wouldn't hurt, but the level is good and oil looks good.

That is what I was thinking. But just how easily will it unlock? Because this scenario is fairly common, I'll be cruising at 80. It'll be right ~27-2800, then I won't perceive a hill but it will go up to ~3100rpm. I can't imagine constantly unlocking and riding higher rpms, is helping my mileage any.
Not to mention it's just annoying because the vq has the power at that range to climb a substantial grade, and give good passing acceleration.
Is there any way to make it lock, or maybe even just make it lock up more often? In searching it doesn't seem like it.

 

Doesn't the T/C unlock at a certain MPH on the Maxima? ...I think it was around 73-80mph.. I remember because I had to stay around 75 to save gas by staying around 2.5k rpm and anything after that speed my RPMs would be in the 3k range..

 

It depends on a few factors, tranny fluid temp, RPM, load, throttle angle, etc.

 

That's why I set my cruise at 3krpm. And for the first while, and even long after my temp is reading normal. 3krpm= ~75-77, then after about 20-30 minutes, 3k=83-85.
And so mythinking, is that my usual driving isn't this long or extended. So it makes me curious what kind of mileage I'm losing due to it always using higher rpm's.
Got any link love Nmex?

 

Just a question - When you're driving and taking note of how your rpm changes at a set speed, is it always over the same place?

Do you always drive a specific route and notice that at some point the rpms are lower for a certain speed compared to the other?

Or is it like if you drive through one stretch of the highway and 20 mins drive over the same exact stretch and your rpm and speed don't match what it was previously?

 

So recently I was put on a job that is an 80+mile commute each way. And the commute is about 3 miles highway, then about 80 miles freeway, then about 2 miles highway, and finally another 2 miles small country town. Before I hit the freeway, I get one stop sign, and usually one stop light. When I get off, usually only get one light.
And so I've noticed this all because I was setting my cruise to have the rpms, right at 3k. Then I started to notice how the speed would fluctuate while at 3k. And also how the rpm would seem to be a few hundred higher at the same speeds. Specifically I was setting the cruise at 80, and sometimes the rpm would be 3300, then other times could be 2900.
Which I think it is something about the torque lock, because I have seemed to notice it'll start dropping after 20-30 min's, about 15 freeway miles.
I try to only make an observation on what I feel to be flat(the majority of the drive) road. But the exact same location, no I haven't been that specific.

 

What grade gas are you using? Maybe using a lower grade gas than premium causes more of a load on the engine.. because it retards timing to compensate

I get around 22-25 on the 350z (According to the computer) while going 75-80.. (6speed though)

 

Well te auto trans sometimes runs between 2 gears at the same time making the rpm rise and fall according to speed. Especially when on cruise control when the car senses it needs to accelerate or decel up and down hills it rides in both gears at the same time. Whether it goes up or down hill the rpm should fluctuate with teh condition its riding on

*edit
To make it simple. when you cruise at 60, the car stays at around 2300 on a flat surface. When you get to a small incline, it senses that it is slowing down and wants to maintain the speed it is set on so it ups the RPM a little bit to comphensate for a little extra power to keep the speed. or when you are at a decline, it rides between 3 and 4 gear to slow it down a little bit, and thus rising the RPM again since its in a lower gear.

I guess thats how i would explain it. idk if thats what you want to look for or if there is actually a problem with your ride performance wise or whatever. im jus adding what I think might be it.

 

http://www.nicoclub.com/FSM/maxima/2003/at.pdf

 

Ok, so over the weekend I read up, and during my oil change, I did the trans fluid as well. will see what/if any impressions I get. Worth noting though, when I was checking my trans fluid, it appeared red on the white rag. But when I drained/flushed the fluid, it was a nasty brown color, not at all reminiscent of red.

In the mean time: I changed the air filter with the oil change. I have just the factory intake. And now I got a p0507 code(idle air). I tried the idle air learn several times to no avail. Then today I have done ecm reset>accel pedal learn>throttle closed learn>idle air learn, several times. Every time I do the idle air learn, the rpm will drop to like 800rpm, but once I start it back up it'll raise back up to about 1100rpm. Any ideas(noticed you were in most the p0507 threads I was looking in Nmexmax).