Hey Guys,

I've been pestered with this symptom for roughly 2 yrs, and have recently decided to record it since it's a bit difficult to describe. Everytime i drive past 45MPH and allow the car to either roll to a stop or brake, right at 1500RPM the RPM's drop suddenly to roughly 1000RPM and then back up to 1200 then down normally.

My car is a 2002 Maxima SE 4AT. The only performance mod i have is a Injen CAI, which i plan to swap with a stock intake soon. I'm hoping someone either has come across this similar symptom, or can assist with diagnosing the problem. My theory is it may be either an ignition (Coil Pack) or Air Fuel (MAF) issue, but before i start shelling out money i'd like some opinions from you fine Org'ers. FYI Coil packs (no dots on them, maybe diffective batch?) and MAF are the original parts. The car currently has 93k miles.

You'll notice that my SEL is on, but this just recently turned on so this shouldn't have any correlation with the symptom i'm describing. (P0159/1167 O2 sensor)

http://www.youtube.com/watch?v=JFHSuYZXgcY

Edgar

 

Someone please step in if I'm wrong on this but...

It looks normal to me. It looks like the car is downshifting from 4th and the torque converter is unlocking. From what I understand the torque converter locks up at around 45 mph to help hold the rpms at highway cruising speeds.

I wouldn't worry sir, looks like a normal downshift to me. I'm pretty confident but can someone else chime in and confirm this?

 

my 2002 i35 does the same thing. i would agree with TeH BawNeY.. it's all normal buddy.. nothing to worry about.. i had an issue with coild pack #3 but the symptom for that was when my car was in "drive" and i was idling at a stop, the rpm would dip down to almost ~300-400 and come back up to normal rpm between.. when i had a maf issue, my car would hesitate rpms would constantly dip down and felt like i was running out of gas or something. once the maf completely crapped out my car wouldn't even start.. i disconnected the maf plug and the car started.. i've been thru these problems as im sure many maxima/i35 owners have.. and what i see from your video, it looks normal..

and btw an o2 sim is the ****!! my secondary o2's went bad and it was a cheap solution!

 

You guys are correct. It is the TCC unlocking, which is perfectly normal, at about 40-43mph. I never understood why Nissan would program the TCM like this though, every auto I've ever had unlocks immediately when the accelerator is released, at any speed. I think their setup improves engine braking, but hurts fuel economy. These cars use the TCC a lot.

 

I guess i never noticed it until the first time i caught it in the corner of my eye. Ever since i always thought it was a symptom of something going bad. It's comforting to know this is normal, but now i try to think back if this also occured with my 95 Max? I wonder if 4th gens had the same TCC setup? Anywho i really appreciate everyone educating me on the TCC.

Edgar

 

its the torque convertor unlocking itself.
usually it locks up when you go above 50mph ish.

 

I'm almost positive the '95 Max had an electronic trans control, but it didn't have Drive-by-wire, DBW. The cable systems were a little more crude but probably adhered more to the traditional auto logic, meaning, when you step on the gas, the tcc unlocks, or when you lift off the gas, the tcc unlocks. With DBW, the computer deems it unnecessary to unlock untill the vehicle reaches a mph (41ish) or throttle percentage (+50%) threshold. Like I said before, I don't like the logic of the TCM at all. I wish that someone would offer a TCM upgrade for our cars that would fix the nuances of the factory TCM. This has been the main issue with my Maxima that I can't overcome. This and the shift schedule. (rpm vs. throttle position)

 

It's as normal as green grass.

 

that comes standard on all years.
its normal