[TEKNO]

Hiya all, just want to quiz you on something....it became evident just after getting my Jimny that when its cold and I drive off that it wil not change into top gear until it reaches normal operating temperature in which is fine IF I lived in the suburb's which are generally 50 or 60 zones,however I am in a rural area and the road out front of my place is a busy 100km zone,so every morning I sit in my car for about 2 minutes approx warming it up then drive off but really cold mornings like this morning,I drove for approx 3kms with the car revving at around 4,500rpm stuck in 3rd gear coz it does'nt change til its normal operating temperature. I spoke to Suzuki and was told that this is quite normal for it to do that as its something to do with Emissions and I also found out that my mates Rav 4 auto does the same thing and so does my Niece's Mazdz 121 auto.
So it would seem that this is how it's meant to be but I find it annoying because it sure sounds bad when its revving high for so long and of course if I slow down to around 80kms I get harassed by the driver's wanting to do the posted 100kms. So does anyone know if there's a way to get the Trans to shift into top gear when cold or perhaps im worrying for nothing??? And if I do add a Trans cooler I imagine it will take even longer to warm up?
All thoughts appreciated
Tanku

[Gwagensteve]

It's normal.
No, it won't take longer to warm up with a trans cooler fitted. The temperature is measured in the engine coolant, not the transmission fluid.
I don't believe there's any feasible way around it. I believe the trans is controlled by the jimny ecu. Modifying the temp the computer sees will result in the engone being incorrectly fuelled

Steve.

[DC3PTIKON]

The Jimny auto transmission has a transmission fluid temp sensor in the pan, and runs its own TCM.

[Gwagensteve]

Does the auto trans shift protocol depend on trans temp or coolant temp? In the AW-4 it's based on coolant temp.

I don't recall seeing a TCM when I did gregc's g13bb/auto swap.

Steve.

[HarryHoudini]

I've seen this mentioned often in my trips around the net,lots of different manufacturers have their Auto's programmed not to shift into O/D until the motor is at full operating Temp & possibily the Auto's oil as well.

Post..22177

http://www.bigjimny.com/index.php/forum ... ic-gearbox

[TEKNO]

Interesting......I should mention that I believe my auto is a A174,4 speed with overdrive I was told.

[DC3PTIKON]

Gwagensteve wrote:

Does the auto trans shift protocol depend on trans temp or coolant temp? In the AW-4 it's based on coolant temp.

I don't recall seeing a TCM when I did gregc's g13bb/auto swap.

Steve.

The Jimny box is fully electronic so the shift is determined by trans fluid temp. The TCM will also inhibit convertor lock-up until operating
temperature is reached.

By memory the TCM should be on top of the ECU behind the glovebox.

[TEKNO]

Okay,so if my trans shift is determined by the fluid temp,then adding a trans cooler will only make it stay in 3rd longer when cold due to the fact that it's no longer running through the radiator? Correct?

[Scrawny]

A correctly fitted cooler should be plumbed in AFTER the radiator cooler

[Photog]

According to the auto transmission specialist I spoke to the cooler should be fitted INSTEAD of the radiator cooler, and that is what he did on my Jimny, he's the expert.

Mine warms up reasonably quickly at idle, in "D", with the handbreak on if that's any use to yu. Mind you this is not exactly a cold place.

[DC3PTIKON]

Scrawn wrote:

A correctly fitted cooler should be plumbed in AFTER the radiator cooler

Exactly!!!

I would never run a external cooler without the radiator cooler also being used. Imagine the trans fluid temps sitting in traffic, towing, or even worse driving in low range through sand with little to no ram air flow. The trans would be cooking. The external cooler alone would be useless.

Liquid to liquid cooling is much more efficient, then also run the external cooler after the radiator cooler. Also since your problem is that the trans takes too long to heat up, having the radiator cooler still plumbed up will assist in warming the trans fluid initially and help it get up to temp with the warm engine coolant.

[Gwagensteve]

My advice and experience disagrees with this. I'd rather not be heating my trans fluid by running it through the bottom tank of my radiator.

My aw-4 generally runs cooler than the bottom tank of my radiator.

[christover1]

My auto is evil when cold, although improved with brand change of ATF.
It won't hold low in descents, changes up gears itself, until warm.
This was disconcerting till I got used to it.

After trying different configurations of extra cooler in long term on and off road use,
I settled on running stock radiator cooler with extra after that.
Worked best all round for my use.

[Gwagensteve]

My auto is perfectly behaved once engine coolant is slightly warm. Auto temp is irrelevant in my instance as I don't run the trans fluid heater in my radiator.

Trans temps average 75-85 degrees on the flow to the cooler, so I can only assume my trans would run a minimum of 10 degrees hotter at all times if I ran the trans heater, all other things equal.

Gregc doesn't run a trans heater with his jimny auto. Jimny autos run hot enough as it is, the last thing they need is a "cooler" adding heat.

[DC3PTIKON]

The radiator cooler is a tried and tested system. The amount off heat added to stone cold trans fluid would be small. I know in other parts of the world were it is very cold, people have removed the radiator trans cooler, run the external cooler only and have had huge amounts of trouble with shift quality and hanging in gear due to the fluid being more viscous etc. And as soon as the radiator cooler was reconnected, the problems disappeared. So yes, the radiator can 'initially' assist in warming the fluid in the cooler in very cold climates. The primary job of the rad trans cooler is to remove heat and is very effective at doing this. Heat exchange occurs hot to cold, and in lower radiator tank temps VS the trans fluid temp in the radiator trans cooler, the trans fluid is hotter. So heat exchange would be from the trans fluid to the coolant. So at normal operating temps the only thing that would be happening is the 'transmission' fluid being cooled, not the other way around.

[DC3PTIKON]

Gwagensteve wrote:

My aw-4 generally runs cooler than the bottom tank of my radiator.

Just wondering, how was this measured?

[jdk81]

^with a trans temp gauge etc

Almost every single discussion on autos, Steve says to fit a trans temp gauge.


You can try standing on the brake and rev the engine a bit to heat the trans fluid if you desire. It doesnt take long.
However on my baleno and sierra with vit engine and auto, I tired and it doesn't make any noticeable difference, as both rely on coolant temp and take a while for it to get warm and find 4th.

[Gwagensteve]

I'll admit I'm making some assumptions, but my trans frequently might be sitting at 40 degrees. The bottom tank of my radiator isn't that cool once the engine is up to temperature. My trans temp gauge is on the flow to the cooler, so in this instance the flow from the cooler into the trans is cooler than that. That's unachievable if the motor is at operating temperature with a radiator mounted "cooler"

I'll repeat- I don't want my trans temp coupled to my engine temperature.

The only reports of poor shifting due to over cooling are at temperatures well below we see in Australia. Generally from North America.
You can't have it both ways- the efficiency of liquid/liquid coolers is indeed high and that works both ways. The radiator will be just as efficient at adding 25degrees of temperature to the trans as it is removing 25 degrees. It won't cool efficiently yet heat inefficiently.

[tanshi]

Its not a typical road going situation but our race jeep had all sorts of over heating issues until we separated the trans cooler away from the radiator.

[TEKNO]

Wow guys,deep. But what I can tell you is that again this morning at 7am when I took off the outside temp was 3.2c and I took extra notice of my temp guage which got up to temp but the trans clearly had not changed into top yet until about approx another 1.5kms down the road so this tells me that it does have the trans temp guage in the trans itself and not measured by the coolant temperatures! So I will look further into a trans cooler but there is obviously some conflict as to the best way to have it installed? i.e. with rad or on its own up front. At the moment to aid with warm up,im leaning towards just leaving it stock but theres always the concern in summer especially when towing that maybe I should get a cooler installed? I know my Pajero had a seperate trans cooler up front and that was fine,but hey,thats also a very different vehicle and a diesel also,cant really compare.
I spoke to my local 4wd shop and he said he could install a Trans cooler for me for around $270. Dunno if thats a good price or not,I will investigate.

[Gwagensteve]

Install a transmission temp gauge and start making observations.

Every automatic jimny needs a temp gauge regardless of use in any case.

For the record, gregc's jimny auto equipped sierra runs two 250x250mm trans coolers. One in front of the radiator wasn't sufficuent to keep temps under check on hot days.
It is correctly geared for its tyre size, which is more than can be said for many Jimnys.

Steve.

[TEKNO]

Bewdy,thanks Steve,I will look into that. Apart form the bigger engine,mines completely stock so gearing is not an issue and I wont be changing,im not a serious offroader,just love suzis.

[TEKNO]

Gwagensteve wrote:

Install a transmission temp gauge and start making observations.

Every automatic jimny needs a temp gauge regardless of use in any case.

For the record, gregc's jimny auto equipped sierra runs two 250x250mm trans coolers. One in front of the radiator wasn't sufficuent to keep temps under check on hot days.
It is correctly geared for its tyre size, which is more than can be said for many Jimnys.

Steve.

What about the Scan Guage 11 I keep hearing about? any good? Can I adapt to my Jim?

[Gwagensteve]

I doubt auto trans temp is measured- I suspect it's just a switch like fans use.
You'd want to know auto trans temp was a measured parameter before you bought a scan gauge primarily to do that job.

[Bulldog 61]

Photog wrote:

According to the auto transmission specialist I spoke to the cooler should be fitted INSTEAD of the radiator cooler, and that is what he did on my Jimny, he's the expert.

Mine warms up reasonably quickly at idle, in "D", with the handbreak on if that's any use to yu. Mind you this is not exactly a cold place.

Bypass the radiator cooler is the way to go and run a separate transmission oil cooler, two things kill auto's (water and heat). I am assuming you are running some sort of cooling fan on the transmission cooler.

[christover1]

One expert told me warmer temps good for reducing condensation in the fluid.

[atari4x4]

http://ekmpowershop2.com/ekmps/shops/co ... -477-c.asp

[britvit]

Stick one of these on the motor
http://www.aliexpress.com/item/free-shi ... 83331.html
and one of these on the auto pan
http://www.aliexpress.com/item/Engine-p ... 03570.html

[Gwagensteve]

christover1 wrote:

One expert told me warmer temps good for reducing condensation in the fluid.

Does your expert want to think about that more carefully? A trans that holds a higher operating temperature will draw in more air as it cools, increasing condensation. Condensation is a product of large temperature changes, especially introducing cool outside air on cooldown. You couldn't run an auto trans cold enough to prevent the expulsion of condensation. It would have to basically hold within a few degrees of ambient in operation.

It's pretty frustrating - people read on the internet about someone in Canada complaining that they fitted a big cooler and they're now overcooling their trans, so they think it's going to happen to them if they stray away from the factory heater. It gets to -30˚ in Canada. Of course you can overcool an auto - they need block heaters so they can get their engines to turn over from cold.

Apparently an auto won't shift is it's overcooled, yet I can get in my car from stone cold in the snow at -5˚ and it shifts just fine, incredibly without the trans fluid heater the factory installs.

[striker99]

Gwagensteve wrote:

christover1 wrote:

One expert told me warmer temps good for reducing condensation in the fluid.

Does your expert want to think about that more carefully? A trans that holds a higher operating temperature will draw in more air as it cools, increasing condensation. Condensation is a product of large temperature changes, especially introducing cool outside air on cooldown. You couldn't run an auto trans cold enough to prevent the expulsion of condensation. It would have to basically hold within a few degrees of ambient in operation.

It's pretty frustrating - people read on the internet about someone in Canada complaining that they fitted a big cooler and they're now overcooling their trans, so they think it's going to happen to them if they stray away from the factory heater. It gets to -30˚ in Canada. Of course you can overcool an auto - they need block heaters so they can get their engines to turn over from cold.

Apparently an auto won't shift is it's overcooled, yet I can get in my car from stone cold in the snow at -5˚ and it shifts just fine, incredibly without the trans fluid heater the factory installs.

Just with regards to minus 5, where I am living at the moment temps drop to between -5 to -12 during winter. With the auto from a cold start, usually changes into top gear in the auto with in a few minutes. Disclaimer is that the car is kept in an enclosed garage with an ambient temp 20 degrees warmer than outside.