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Discussion Starter · #1 ·
Hello all,

So I noticed a weird issue today, wanted to check with the experts (e.g: you all) to see what you think.

When I was driving on the turnpike today, I noticed my RPM's get a little jumpy (up and down) only when I am around 1.2k to 1.5k RPM and I am not accelerating anymore.

The truck is an 06 Xterra S, with about 72k miles on it. I do an oil change (full synth) every 3k miles, and my last tune up (engine flush, tranny flush, radiator flush, spark plugs, PVC) was done at 55k about a year ago. I don't know when the distribution caps were changed, but I am leaning towards thinking this might be the issue.

Oh, and it only happens sometimes.. not always.

The RPM's are stable when idle, and when accelerating they are fine also. I don't feel any tranny slipping and I don't hear any grinding / unhappiness from my tranny (at least to my untrained ear).

Thanks again all. Forgive me for the stupid question, I am still learning the mechanics overall :)
 

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how much of a jump, it could just be the transmission downshifting as you slow down, mine does this too and it seems normal - but its never an aggressive downshift you wouldn't notice it if you were not looking at the tach.
 

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our trucks do not have a distributor cap. they do have plug coils on each plug. with that said, what you are describing sounds normal. mine has done it since new and i now have 111,000 miles on her.

i have noticed that it downshifts into lower gear more than it used to BUT that's probably because i am visiting the steep mountains more than i used to. for example, when heading down a steep hill at 60 and if i hit the brake good, it will downshift into 3rd and stay there until i hit the gas again. it did this when new coming down mt mitchell and i thought there was an issue but it's the transmission's way of slowing you down, which i like.

back to your issue, my tach hops up then comes back down when decelerating alot and i chalk it up to normal....
 

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Sounds normal, but it can be excessive (which was caused be me). I had to do an idle relearn at one point after some tuning and a Volant, but that got things back to normal.
 

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Discussion Starter · #6 ·
Its weird, it will drop and then go slightly back up. The only reason I noticed it originally was I felt the truck jerking (but it could have been the uneven pavement of the NJ Turnpike) but once I hit the OD switch on / off it stopped.

It happened a few other times, but it felt smooth either way.

The idle relearn sounds like it might be the case. I did just throw a Volant in there and lift it up...
 

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I am getting the same thing these days, well after overheating my tranny a few times towing specifically. While I would agree its generally normal it appears to be a little more noticeable now. Changing my trans fluid this weekend, we'll see how it is afterwards. 06 with 99,000 also with a Volant but that's been on there for almost 90k.
 

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Sorry for the resurrect. I have a similar problem and because I'm not used to automatics I'm not sure if it's normal. Everything seems to shift fine when accelerating but if I quickly take my foot off the pedal and while coasting the rpms drop low immediately (below 1000) and then a second later bump back up to normal 1200 or so. It just seemed kinda jumpy in general whenever I'm decelerating or coasting no matter the speed. I couldn't tell you if this had just started or was always like this. I can't even tell if it's a engine or transmission thing.


I had just reset the codes yesterday, would that cause the computer to maybe be relearning?
My other thought was I need to replace the cat converter and maybe backpressure is causing the rpms to drop further than the computer is expecting and so it has to correct?
I also blasted the MAF sensor with MAF cleaner.

2005 SE 4x4.
 

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Sorry for the resurrect. I have a similar problem and because I'm not used to automatics I'm not sure if it's normal. Everything seems to shift fine when accelerating but if I quickly take my foot off the pedal and while coasting the rpms drop low immediately (below 1000) and then a second later bump back up to normal 1200 or so. It just seemed kinda jumpy in general whenever I'm decelerating or coasting no matter the speed. I couldn't tell you if this had just started or was always like this. I can't even tell if it's a engine or transmission thing.
Mine does the same. When I let off the gas completely at lowish speeds it quickly drops from 1200 rpm to 750 and then back up.
 

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Having a similar issue after changing the spark plugs. When I start slowing down -
regardless of decline or flat road - my engine makes a few revving pulses before I fully stop.
Of note, I'm getting a po420 code, so my catalytic converters need replacing (180k miles now). Maybe that'll fix it.
 

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If anything, it could be the spring inside the torque converter, the one that sets the stall speed, that may be getting worn. My X does this as well...new symptom, but perhaps I just never noticed. I don't plan on doing anything to correct it or explore it any further.
 
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