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V6 UK-spec torque converter lockup

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Al_____

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Discussion starter · #1 ·
Hi.
I searched for this phrase and found 16 non-specific threads.

Got a new V6 Outlaw auto in the UK. At first I realized an MPG of around 20 (on a good day!).
I then realized that some kind of valve/trigger (I'm non-technical) seems to lock the TC at exactly 3000RPM at any speed.
Clearly with a locked TC the MPG is incredible (for a vehicle of this size, bulk and profile) I get 29.2MPG (for my driving style in a good mood), but typically 28.5 under any driving conditions.
The truck also pulls much better in general at lower speeds, does not hesitate at lights and has engine breaking that works down hills.

Under normal circumstances, because of the huge torque and large number of gears, it is very difficult to lock the TC unless driving like a lunatic.

However, I find that if I just blip the throttle above 3000RPM in 2nd when first setting off, that the vehicle transforms. The 0-62MPH time also drastically improves to about 7.5 seconds [iPhone app measurement].
You only have to do this once per journey; even when shifting into neutral the TC stays locked and has instant take-up when you put it back into gear as opposed to that rubbish 1-second delay and vague/distant power deliver.

I was wondering is this is expected; I haven't heard anybody noticing it, although indirectly it's likely a possible explanation to the vast disparity in MPG returns people get.
Is this common knowledge and I have stumbled on something that could be useful to many members, or I am just a dunce and everybody knows this!? ;-)

Maybe when they lifted the base gearbox from the 370z they should have lowered the lockup-pressure whatsit to 2500RPM, or even lower?

Thanks,
Al.
 
#4 ·
I'm not 100% sure on the navara, but on most applications the torque converter shouldn't lock up until your in 3rd gear. Tc lock up before this can cause excessive damage on your gearbox clutch packs and if past experience on auto boxes is anything to go by then its cheaper to replace complete box.
It has a tc on it to aid in getting the motor rolling, maybe it will lock up in second if your empty and on flat or downhill but if i were you i'd only open it up from 3rd upwards and let the tc do its designed job in 1st and 2nd, or the slight saving on fuel could cost double in a new tc or box.
 
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#5 ·
Hi All,

That's a really good first post. It makes a change for someone to come on and offer valuable information first time. :bowdown1

It would be appreciated if you visited the 'Introduce yourself' section and tell us more about you and your Navara. You'll get a warm welcome to the fold :awesomework
 
#6 ·
I'm not 100% sure what the OP is trying to explain. How do you blip the throttle in 2nd gear when it's auto?
 
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Discussion starter · #7 ·
Hiya.

The original post was not 100% clear.

I guess I should have mentioned that on a vehicle with this much low-rev torque and 7 ratios, you can easily drive for years up to fast motorway cruising speed without ever locking the TC. I'm 90% certain that it will NEVER lock if you stay below 3000RPM in any gear. It's not until you go (in theory/on paper) above 90mph that you'd get close to 3K, which in the UK means never.

I got the impression from mine that a great many people are disappointed with sluggish performance, poor economy etc simply because they drive 'normally' and my conclusion that the manufacturer not pointing this out was a oversight. When I stumbled across this, my opinion of this vehicle then transformed from grossly underwhelmed to ecstatic - to the point I don't ever want another car. Well maybe a Caterham on tow behind me ;-)

Al.
 
#10 ·
I think what the OP was trying to explain was that the gearbox on the V6 can lock the torque converter if you rev it over 3000rpm initially then it locks the TC at lower revs. I've often found the box in the wrong gear when leaving an island and have to kick it down a gear.

Interestingly I've been using the cruise control more and more lately. If accelerating gently from a set of traffic lights to 70mph on a dual carriageway; using the accelerator the truck uses all gears and revs high. If the cruise control is resumed back to the previous setting of 70 the truck doesn't rev anywhere near as high when compared to being manually driven and the revs never exceed 2k but it still gains speed quickly.
 
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#11 ·
Could you not use the semi automatic mode ? in my 2.5 auto if you put your foot to the floor it revs to 4000 in every gear, semi auto mode ( + / - ) is even quicker.

So are you saying the V6 is different? sorry for seeming a bit thick!!!!!!

:scratch:
 
#12 ·
I picked up my V6 last Saturday, I have noticed that if you push the gearstick to the left it goes into sport mode, it remains in auto but accelaration is mind blowing if you then push the gearstick forward or back it goes into manual mode just like my old tekna 2011 did.
 
#13 ·
Having owned a V6 for two years and then getting rid of it I don't have much good to say about this gearbox. Maybe it has been tweaked but mine was awful.....slipping under hard acceleration on the motorway even in 5th and never in the right gear around town.

Talk of tc's locking up for a whole journey are a mis-informed. The tc has two jobs, to transfer torque from the output shaft to the gearbox, and to allow the engine to spin freely when the vehicle is stationary. If it stays locked then your engine would stall every time you stopped, simple as that. Also when pulling away it has to slip until the car speed matches the engine in a particular gear, likewise during gear shifts.

A tc is basically two set of turbine blades immersed is hydraulic oil, and the fluid being spun transmits torque. Lock up tc's only really became common in the last 20 years, and this is achieved by having a mechanical lock which locks the speed of the two halves of the tc. This only happens when vehicle speed and engine speed are closely matched, just like how it possible to change gear in a manual without using the clutch if you know what your doing. All shifting in an auto is achieved by diverting gearbox oil to various actuators by means of solenoid valves. In modern autos the ecu decides how and when to open/close the solenoids, and therefore shift gear.

What you might have stumbled on is a (handy) glitch in the ecu programming that changes the lock up speed and shift pattern for the better. . Likewise this sport mode thing might be a left over from the previous programming that was never properly removed. Nissan should really let people know if this is the case. But there is definitely a well documented lag in engine response from a standing start, and if this is also altered simply by revving above 3000 I would be very surprised

In the end I could live with that gearbox (which was designed for a sports car) and sold mine. Got a Merc M-class now and the engine and auto match is silky, actually what the Nav should have been....

Some good advice though, fit tough dog shocks on every corner and the ride and handling is transformed:)
 
#14 ·
Al_____ said:
However, I find that if I just blip the throttle above 3000RPM in 2nd when first setting off, that the vehicle transforms.
Click to expand...
Apologies for resurrecting such an old thread.

By blipping the throttle I take it you are going along at 20mph or so, moving the gear selector to neutral, blipping the revs to 3k or more, letting them die down to tick over then going back into gear and that is when you see the torque converter lock up and provide the benefits you mention? Or have I mis-understood completely?
 
Discussion starter · #15 ·
swallington said:
Apologies for resurrecting such an old thread.

By blipping the throttle I take it you are going along at 20mph or so, moving the gear selector to neutral, blipping the revs to 3k or more, letting them die down to tick over then going back into gear and that is when you see the torque converter lock up and provide the benefits you mention? Or have I mis-understood completely?
Click to expand...
Hi there. No. I'm sorry I described it incorrectly. I meant basically blip the throttle while in gear to get above 3k rpm to actually lock the TC.
The problem (not a problem it was just bedding it) was that I had to drive slightly aggressivly to make it lock. Once the TC locked it was a different beast. Once locked of course it stays locked at any speed.

It reduced after 5k miles or so, but now after 42k miles I still find if really pootling slowly through traffic the TC won't lock until you get on open road. It's not a design flaw I think, just a heavy gearbox and TC combo. I think it's how most autos are designed it's just that most people don't notice.
HTH Al.
 
#19 · (Edited)
swallington said:
Out of interest, I think yours is a 2014 if I remember a previous post correctly?

AI, what year is yours?
Click to expand...
Yes it is. The autobox is amongst the best I've tried, including a fair few upmarket cars (say £50K plus, but the Nav is obviously noisier on full blast and handles like a two-wheeled wheelbarrow full of paving slabs). I am puzzled as to the reported autobox differences! Maybe be S/W tweaks.

I am amazed that for a crummy Nissan, it is usually in the right gear (esp. in Sport mode) and changes smoothly, and really does seem to anticipate me. Even when I am being vicious on rare occasions, and drive it like an "M" car...
 
Discussion starter · #20 ·
It drives perfectly unlocked, it just seems a bit like it's hunting and using a few too many revs. It's fine; its designed like that.
If you've just brought one, congratulations! It's the best pickup by far I have ever driven with zero defects so far at 42k miles.

From brand new it was getting like 19mpg on motorways - a nice tight engine. I'd say you won't approach anything like 25mpg until around 20k miles. It wasn't until around 30k did it really open up and start showing it's true colours as you have found, at 30k miles I typically get 28-31 MPG (averaged over a full tank and long motorway trips). That's with quite sedate driving.
At 35-40k miles I'm actually getting up to a peak of 33-36MPG, and that's with mud-and-snow tyres.

One interesting thing however to achieve that, the toe I understand (being a non-technical computer guy) is 7-degrees factory-spec (or something) and at that, you'll get maybe 31mpg, as per the book stats. However, I noted that I started getting more and more MPG up to 37PMG on the way to Scotland (400 miles without stopping).
To cut to the quick, I had the tracking re-done and they said it was at either zero degrees or toeing out slightly hence the super-mileage. I had it reset to 7-degrees and MPG dropped again. I asked the guy to set it to 5 degrees and it made a difference. It is the biggest relationship (outside of actually breaking the engine in). Somebody far more knowlegeable than I could have a play and see if it is a true observaation or coincidence.

Tyres. I would STRONGLY advise against mud-and-snows. They feel a bit unsettled on mine. Stick with the continentals on there which are the PERFECT choice for the vehichle. They last a long time, drive really well, AND are excellent in snow as well. Or have a spare set of full-muds to throw on in winter-only.

Shout any time. Al.
 
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