Hi guyz,

I have bought 2006 R51 Pathfinder and I've already begun with some mods. Started with engine cleaning/decarbonizing (with some taps off water), MAF cleaning, ATF fluid full change (draining + circulating until fresh = 14 litres of new ATF instead of 10) and finally EGR disabling (by pulling out solenoid valve actuator, no blanking needed).

Now, when in 4HI or 4LO modes with differentials more tight (seems both front and rear are unknown percentage LSD, because on asphalt tires squeek and scream a lot when turning in those two modes)...well, what's weird is that it seems like transmission/transfer is very tightly coupled to engine, so whole vehicle bumps at slight touch of gas pedal.
It is not anymore "nice and soft" acceleration from stop to moving (like in AUTO or 2WD mode), but as soon as I press gas pedal just a bit, wheels start turning instantly.

Might it be that torque converter is fixed in 1:1 coupling, without any smooth torque conversion in 4HI and 4LO modes?
...or should I give my torque converter a check?

BTW...there are NO diag codes, not in ECU nor in TCM. Stall RPM is around 2900 and torque converter LOCK engages and disengages at predicted speeds, so by diagnostics it looks healthy.

Did you use the correct automatic transmission fluid, Nissan Matic Type "J" or "S" or equivalent?

Actually, listed mods are on my list and are in realization, so all are done, except ATF change, as I am still waiting the missing 4 liters of ATF to come

So, I am not sure what's actually inside at the moment, but since previous owner warned me to use only Nissan OEM Matic-J/S fluid, I guess that's what is really inside.
Level of ATF is exactly at LOW limit, but it does not smell burned, nor it is mixed with coolant (as far as I can smell).

You think it might be ATF?

It's hard to say without being able to drive the vehicle or view datastream information. I can tell you that Dexron III/Mercon will ruin the torque converter, so make sure you use the correct ATF; most synthetics are compatible with Type "J" or "S." Valvoline Maxlife ATF and Castrol Multi-import ATF are both good aftermarket options.

Gotta ask, are you driving in 4WD on dry pavement? Aside from the LE model with full time AWD (what's labeled AUTO on yours) the other modes don't allow slip between the two axles at the transfer case. The upside is increased traction when you're in mud, snow, or ice, but the downside is you can't really drive on pavement without destroying your tires or something else.

That would be why your front and rear tires are fighting each other. What you're describing is normal for the SE and other models in 4WD. At highway speeds on dry pavement it'll start rumbling pretty quickly...

labsy wrote:..... because on asphalt tires squeek and scream a lot when turning in those two modes)...

Sounds like your problem is your turning while driving on asphalt in 4WD. Recommended against in all instruction manuals.

I get it that english is your second language so from what I'm reading you're expecting it to act like an all-wheel drive vehicle would ala Subaru instead of how it is acting ala 4wd. If my interpretation is correct you need to adjust your expectations.

Hiya,

well, as you guess correctly, English is not my native language, so I probably did not accent real problem, but instead described the principles on how I assume why it is LSD and not just ABLS.

So, the problem is not about tires squeeking in 4-HI or 4-LO modes on asphalt (which I am quite aware on how it works, so I'd never drive in those modes on hard surfaces with good traction )

The proglem or better say, my question was actually about how torque converter and especially its 1:1 clutch works in 4-HI and 4-LO modes. I guess there are two assumptions:
1.) in 4-HI and 4-LO modes torque converter engages internal clutch and couples engine and transmission in fixed 1:1 ratio; there is no torque conversion, just plain clutsh ON/OFF when you press accelerator pedal
2.) another assumption is that torque converter in those 2 modes works just like in AUTO or 2WD mode, but my question would be, at which speed TC then couples fixed 1:1 ratio for maximum torque

Why I ask?
Because my feeling is that in 4-HI and 4-LO modes vehicle does not start smoothly, but rather jumps as soon as I press accelerator pedal. You can imagine that jump/kick tilts the whole vehicle at that moment and my foot unintentionally moves a bit on accel pedal, so starting action is kinda jumpy, like somebody would keep kicking vehicle from behind.
It is hard to control smooth and slow going on picky off-road terrain.

Is it normal behavior?