txe5502

I just had my transmission rebuilt about 2000 miles / 2 months ago, and I have spliced the torque converter lockup lead on the TCM wiring harness with a switch to +12v so that I can manually lockup the torque converter in order to keep my trans fluid temperature down under certain circumstances. But I have noticed that just before the transmission downshifts, it seems to slip just a little bit (increasing by about 200 to 400 RPM before actually downshifting). This usually happens either just as I begin to go up a steep hill or just after I increase throttle significantly. I have heard that the F04 transmission has a flaw in the TCM that allows the transmission to slip sometimes. I have also heard there was a recall on my TCM a few years ago (the transmission shop told me this when I got it rebuilt). Is this normal for the transmisson to slip slightly for 1 to 2 seconds before downshifting while the torque converter is locked? If I recall correctly, it also did this when I first got the car when the TC was automatically locked just as I went up a hill.

Max-e-MO!

iTrader: (2)

Do you have a RE4FO4A or the normal RE4F01A? Nissan spend millions designing both trans. and you decided to override the lock up setting? Honestly, if you wanted to control the trans that much, you really should have installed a manual trans. You might have ungrounded the trans in Lock up mode, and can electro-weld the conveter to the trans if your not careful. The slip is being caused by an adjustment by the computer trying to figure out why the lock up is going in and out at it's own discression. (The same thing happens when you shift the O/D button and take the vehicle out of 4th OD and shift it to 3rd OD, it will slip slightly) If your not careful you can damage the clutch lining in the converter by doing what your doing, and will be going back to the rebuilder claiming warrarty, only to find your mod void your warranty.

pmohr

iTrader: (26)

The only 4th gen auto trans is the RE4F04A (or the RE4F04V, of course).

What's this RE4F01A you speak of?

txe5502

I installed the mod for a reason my torque converter produces too much heat and it is necessary for me to lockup the TC long term sometimes to avoid overheating. Believe me this is true especially since I live in a hilly area and often have to move alot of stuff from place to place in my trunk. This is what happened the last time and landed me in the transmission shop, the torque converter melted and took the transmission with it! When I have so much stuff in my car sometimes when I get in extremely hilly areas my transmission temp gauge goes over 200°F if I dont lock the torque converter! Besides that is not the topic at hand anyway. I noticed the slip even before the mod, even before I ever put any heavy load on the car at all, way back in 2005. If the torque converter was locked (without the mod) it would slip just before downshifting when going up steep hills.

I have the RE4F04A transmission

And by the way the reason I didnt swap for a 5 speed is it uses more gas (lower gear ratio) and I already have trouble making ends meet when gas prices get high as it is.

If anyone knows about the slip when downshifting then please tell me.

Please note I have made many mods to this car and still have future plans for it. It is kind of a project car.

pmohr

iTrader: (26)

Incorrect.

Just as with the 4AT, it's all in how you drive.

njmaxseltd

iTrader: (19)

Which is why he burnt up the first tranny.

A trans cooler would have been the way to go.

His second trans is probably doomed as well.


As I've said before, some just don't get it.

txe5502

I have a trans cooler now. It is one of the largest ones on the market that will fit under the hood. It says on the box it is designed for "RVs, busses, large trucks" (lol). The transmission shop put it in for me.

The reason I say the 4AT can use less fuel is because it is geared much higher and can keep you under 1500 RPM at in-town speeds. From that I assume it gets better MPGs given the same driving habits with lower RPM. Also another reason I got my AT rebuilt instead of gettting a 5MT is because I have a huge fear that as clumsey as I am a MT would probably last me about 5 days and be toast, and if that dont happen then I might just have a wreck because of not giving enough attention to the road.

BTW why do you think my second transmission is doomed just because I might not have a trans cooler?

And as for the way I drive. People laugh at me and jokingly say I accel slower than an old lady (this is in an attempt to both save gas and extend the life of my AT)

I try my best to extend the life of the AT as much as possible. I always let off the pedal to allow it to upshift therefore minimizing the slip of the clutches and/or bands when shifting, I put a manual lockup switch to reduce the overall temp of the transmission (but I always remember to NEVER have it locked while driving extremely slow or while stopped). I even paid the trans shop extra to have a trans cooler installed.

For some reason it has slipped like this between changing gears since day one. I think maybe it takes a few seconds for the TCM to figure out if it needs to downshift or something. Whatever it is that is causing this, it is electronic, not mechanical because there is a short delay just before it begins slipping. If I give it more throttle in O/D (such as what you do when you go up a hill), it will remain in O/D for about 2 seconds, then it will begin to slip for about 1/2 to 1 second, then it will downshift to the lowest possible gear. I just want to know why it does this and what I can do to prevent that! One thing I wonder about is my ten thousand exhaust leaks which are messing up the O2s and MAP solenoid (it is messing up the MAP solenoid due to fluctuating manifold pressure, I know this because I replaced the MAP solenoid and the OBD2 code just came right back after that), maybe it slips like this because the TCM might not know the true load on the engine due to bad O2 and MAP readings?

Sorry for the increddiblly long post but there was alot of information that needed to be given.

pmohr

iTrader: (26)

There is such a thing as having the trans fluid too cool.

I can keep my 5MT at under 1500 RPM at 'in-town speeds'

Hell, depending on the speed, I can drive it around sub 1000 RPM.

FWIW between this car being 4AT and 5MT, with me beating on it 10 times more as a 5MT, I get far superior city MPG now.

If it's slipped since day one...why didn't you take it back?

There's erroneous behavior right there. It should not go to the lowest possible gear under light throttle input.

If the code came back instantly, there's a hard failure somewhere.

How would you figure an exhaust leak causes fluctuating manifold pressure? It wouldn't, no more so than if the car had a completely intact exhaust on it. Just because there's a leak doesn't mean you're somehow sucking out more exhaust gases than it produces.

There are few things the TCM takes into account for shifting the trans. The O2s and MAP aren't one of them.

txe5502

Yes I know there is such a thing as having trans fluid too cool, it don't lubricate as well when it is over cooling, but there is (something like) a thermostat in the transmission (per the transmission shop) that tries to prevent the use of the cooler until it has reached normal running temp (about 174 degrees F). It is definitely not over cooling, I have installed a transmission temperature gauge and I can see that. I put that cooler there for a reason, I told you I live in a very hilly area and I often have to carry alot of extremely heavy stuff with me (sometimes so heavy that I have to have help getting some of it into my car), which is the very reason my last TC overheated and fried everything (thats what the transmission shop told me. My transmission fluid runs around normal temp now when I am carrying heavy stuff with me, and just slightly below normal (but not too much) just with normal driving.

Ok, if you have had both the 5MT and the 4AT in your car and it gets better MPG with the 5MT, now I have a good reason believe the 5MT can do better.

When I say it slipped since day one, I meant it slipped just before downshifting since the day I bought the car back in 2005, but it slips so slightly that I can only really tell if it is slipping when the TC lockup is engauged. It was not until I installed my TC lockup override switch that I really noticed the slipping. It generally does this at very low RPM (around 1100 to 1400).

Let me correct myself, I dont know why I said the lowest possible gear, it actually just downshifts one level (from O/D to 3rd or from 3rd to 2nd), but for some reason for about 1 to 2 seconds before downshifting it slips a little (about 200 to 500 RPM difference) like it cant make up its mind on whether it wants to downshift or not. This is only noticable when I have the TC lockup override switch on (because the TC makes slips this slight invisable)

I figured the exhaust leaks right at the manifold would reduce back pressure intermittantly depending on which cylinder is closest to the leak in the manifold therefore causing more vacuum on the intake manifold when that cylinder is on intake stage. What do you mean when you say a hard failure? Where should I look for this?

The transmission shop told me I might want to put a 10 ohm resistor in parallel with my dropping resistor in order to slightly increase the line pressure on my transmission to prevent slipping when I am carrying alot of weight. I have made many mods to this car to try to increase it's load capacity, but I would also like to know your input on this DR mod.

I am starting to wonder if maybe by locking up my torque converter under heavy loads I am reducing the line pressure too much by allowing the pump to run too slow, therefore causing the slip, could this be possible? If so then it might be in order for me to stay in a lower gear while using the TC lockup mod and while carrying heavy loads (keep the RPM higher on the pump under heavier loads), or maybe even not use the TC lockup mod at all and just get a bigger cooler so that the TC can stay unlocked without overheating.

pmohr

iTrader: (26)

IIRC attempting to change the DR circuit at all will result in the same effect as completely unplugging it.

I'd just go with a VB mod, personally.

And there's no thermostat in the trans itself, but generally speaking the higher end trans coolers will come with an integrated thermostat and bypass.

And a hard failure meaning that either the component or harness is completely dead or disconnected. That's really the only time you'll see a DTC pop back up immediately, without at least some time for the ECU to determine a failure.

txe5502

What valve body modification could achieve this? The valve body is kind of complicated and I am not sure if I can do that without a little bit of instructions.

Maybe the cooler thermostat is what the shop was talking about.

Jeez I hope I dont have to completely replace the whole wiring harness, this can be a pretty big job and my OBDII inspection expires April 2009 so I got 15 days to fix that!

txe5502

I will try to make a video of the strange behavior I am seeing in my transmission and post it to youtube but this may take a while because I have to borrow someone elses camera and I have to get them to ride with me so I can drive while they take the video.

Edit
It might be a while before I can take a video of that so scratch that Idea.
Ok, so I think maybe the slip MIGHT be caused by the pump running too slow for that kind of load when the torque converter is locked, causing the pressure on the servos to be too low, therefore causing slipping under load. So with that being the case let me give a little bit of information about why I put the cooler and lockup mod in the first place.

I got this car in 2005 as my first car, I love it I would never drive anything else. In late 2008 I got into a situation that required me to often carry very heavy things with me in my car (heavier than many people might imagine). So in early 2009 the transmission went out, it was stuck in 3rd gear all the time (including in park, neutral, and reverse). I took my car to the transmission shop and they told me the clutch packs were WELDED TOGETHER from overheating long term and that my torque converter was GOLDEN BROWN and had completely melted inside. The transmission shop recommended a very large tranny cooler, and the one they recommended said it was designed for busses and RVs. They also told me the main source of the heat in my transmission was the torque converter, and I know a few things about automatic transmissions and I know exactly how a torque converter works, I have actually had one apart before and tried to make a hydroelectric project out of it but that is a whole other story. The transmission shop put in the cooler and they also recommended that I fix my broken O/D off switch because hauling that much stuff with me while O/D is on could result in disaster all over again. So I went to a local junkyard and got a new shifter and installed it. I also installed a transmission temperature gauge. The trans temp is fine, even when I am pulling my 1400 pound lawnmower on it's trailer to my old teacher's house to mow her yard the trans temp is fine with this cooler, but when I have to haul all that stuff in the car with me (as I said it is heavier than many may imagine), the trans fluid temperature gets to a temperature that makes me a little bit uneasy, because of this I created the TC lockup mod, and that fixed this overheating problem, but it was then that I noticed at low RPM (under 1400 in a low gear), it seems to slip when the TC is locked.

Does anyone have any advice on what I should do to beef up this transmission enough for my needs.

And please dont just say get another vehicle because I like this car too much AND I know this transmission is capable of this, it is also installed in a mercury villager and nissan quest minivan, which are both well capable of this kind of load!

njmaxseltd

iTrader: (19)

Don't want to throw this thread in the wrong direction, but did you ever think that maybe, just maybe your driving the wrong vehicle for your lifestyle?
Perhaps you might be better suited with a Ford Explorer or other SUV type that can carry heavier loads.

I sold a mint BMW 330I when I baught a new home with lots of property.
The Bmer and Home Depot just didn't get along.

txe5502

As I said in the last post please dont just say get another vehicle because I like this car too much to do that and i know it is capable of this kind of load because several minivans that are well capable of this kind of load have this same transmission in them. Also, I have already made many many modifications to this car so that it can fit my needs and I am willing to make as many as I have to. My next plans for this car (after I overcome the trans overloading problem) are to beef up the frame and suspension, I already have that planned out. So please dont waste my time just telling me to get another vehicle, just tell me what kind of mods I need to make.

pmohr

iTrader: (26)

Been there.




That was trans number...2? Or maybe it was the third, not really sure.

Care to link me to a minivan with a VQ RE4F04A?

Just because it's the same trans code, doesn't mean they're the same. Just look at the RE4F04A on the A32, then on the A33. Often times the internals will change, be beefed up in various places (or not, as the case may be), but they'll keep the same trans code.

txe5502

Neither of them have a VQ but both have the RE4F04A:

Nissan Quest
Mercury Villager

Based on the fact that the transmission shop knows what my needs for this car are and that they gave me specific recommendations and put a huge cooler on (plus they were the ones who told me the minivans have the same trans as my car) I would assume they used the strongest internals they could find.

Max-e-MO!

iTrader: (2)

RE4RO4A in a Maxima and a Quest/Villager are NOT the same trans!!!! You would have a hard time bolting up the case to the motor if you mixed these. Intrenal componets are competely different, along with gear radio. I sell Rebuilt Torque Converters for a living, and the two units don't even use the same TC. Nissan is really bad about finding internal componets for unless you find the same make/model/ (and almost)year for used stuff.

Please don't tell me you think that you bought a car because you thought that it had the same trans as a van??? A maxima is suppose to be use for sport/luxury driving, thus higher gear ratio (higher in a 5MT), the van is use for loads with lower gear ratio for hauling heavier loads, hence why van typically don't get better gas milage than most cars.

Pmohr, RE4R01A were installed in earlier style nissan maxima and altimas, I wasn't for sure when the 4th gen. went to the RE4F04A (the 1 and the 4 stand for something ratio related).

As for the cooler debate, there is a valve that opens up and lets the trans fluid flow to the cooler upon reaching operating temps. It typically will open between 100-135 degrees. It mostly there for a car that run up in Northen MN, WI, IA country where is can get and stay at -20 degrees for long period. The fluid becomes like a sludge in those temp, this the need to not cool it till it get to operation temp. They also hook block heaters up on their car to keep the motor oil from freezing, something you hardly ever see down south. Your need for the operation temp valve is obsolete south of KY. When the lowest a temp get down south is avg 25-30, getting to oper. temps. take about 3 min. Pmohr is right, the cooler you can run the trans, the better you will be, HEAT is what kills a trans, DON'T CONTROL IT AND YOU WILL BE ON YOUR THIRD TRANS SOON.


Your best bet to solve your problem is to find you a wreak with a good 5mt, and convert you car to manual.

Of course, (describing you driving pattern) the advice from a mechanic once said to me seem to ring true:"I've found your problem with you car, it appears that there is a very bad short between the drivers seat and the steering wheel!"

txe5502

The transmission shop told me that the torque converter on the villager/quest is different, but the trans is the same, but he said he could not put the TC from the quest in my car because it would throw all kinds of codes if he did that (different stall).

I didnt buy the car at all, in fact, I didnt even know the car had the same transmission as the van until the shop reassured me of that. My dad bought it for me as my first car, long before I knew I would have to use it for anything that I have to use it for, but after driving it for about a year I fell in love with it and would never drive anything else. And I know it is a luxury/sports car. The 5MT has a HIGHER gear ratio??? Interesting, I always thought the 4AT had a higher ratio, I could use a little more input on that. Please take a look at these videos I found on youtube of a car before and after AT to MT conversion.

With AT
http://www.youtube.com/watch?v=Jv79X...eature=related


With MT
http://www.youtube.com/watch?v=EIWe_...eature=channel

I dont control the cooler, I put a bigger cooler in the trans to prevent overheating. I simply control the lockup TC to prevent the TC from generating more heat under load (of course after the temp is close to normal) and also to get better fuel economy beause prices are going up again around here.

Jeez, I wish I had started this thread before my AT fried, I had originally planned to convert my car to 5MT when my 4AT died but I changed my mind shortly before that and now I am wishing I had not. I simply cannot afford another transmission right now as I still owe money on this one. I can just about guarantee that if my auto dies on me again I will get a 5MT though.

I have an update. For some reason the slip that I see at very very low RPM only happens when the trans fluid is hot and the torque converter is locked. Do you think that maybe the reason for the slip at low RPM (between 1000 and 1300 just before downshifting) may be caused by the TC being forced locked and the pump not turning fast enough to generate enough pressure?

njmaxseltd

iTrader: (19)

That's possible and actually sounds logical.
It wasn't designed to operate the way you have it rigged up and could be doing more damage then good.

Might we ask what it is thats so heavy? OR how much weight your actually carrying in the vehicle? 300 lbs, 500 lbs, 700 lbs or higher? Also, where are you putting that much weight and how is the suspension even holding it up?

txe5502

Ok, I admit this I know I have the wrong vehicle for the job I am doing but as I have said before, I would never drive anything else and this car has become a project car for me, I am planning the proper mods to this car that would make it durable enough to do pretty much anything.

First of all, the car is a mobile computer lab, I work on comptuers and I have several desktop computers in the car with a KVM switch and a 17 inch CRT monitor, one of the desktop comptuers is an old AT machine so it is very heavy. Also, me and my parents often go up and down the road to and from the lake (as you can see with my location to the left), but we often stay just days at a time and I always take EVERYTHING with me when I go, so that is alot more load right there. On top of all that, I run a small lawnmowing business and I often use my car to pull my lawnmower trailer to people's houses. Please dont flame me because of this, I am well aware of the fact that this car is not designed to do this, and I have already been told by countless people that an SUV would be better for this job, but please dont forget, I like the car and would drive nothing else, plus I have made many modifications (and plan to make many more) to the car to make it capable of this. I already have the frame and suspension work planned out, I have had a cooler installed, and I have put in a lockup TC switch to reduce transmission fluid heat. Also I have installed a very powerful alternator and a trailer brake controller so that it can safely stop the trailer (car only weighs 3000 pounds with nothing in it)

My plans for the frame and suspension are to first of all, take off the trailer hitch and directly connect it to the back wheels through a frame that I am building (but on much stiffer, stronger shock absorbers) so that the unibody does not have to support the tounge weight, that way I can put more tongue weight on the trailer, thus reducing sway.

I have no need of putting stronger tires on the rear end to support the tongue weight because I have made the calculations and the load will never exceed the max load printed on the tires.

All I need to do now to make this car fully capable of doing what I do with it is to figure out what to do about the transmission issues, I am pretty sure that if I can solve the problem with the slip at low RPM with the TC locked then I will be set to go with this. When I have the max load I plan to ever put on it, it does NOT run hot when the TC is locked, the problem is in low gears at low RPM, it slips.

Could the answer to my whole problem be to simply run it in a lower gear and keep the RPM high?

Please note I know this car's drive train pretty good because I replaced the engine back in 06, it was a huge job that took me a month (was still in high school so I had to do it on my free time)

Also, as I said before, please no flaming because I realize this is the wrong vehicle for this, but as I said before, I know pretty much what mods I need to make to the car so that it can handle this, and I would never drive anything else, right now the only issue I have is that with the transmission.

I am notorious in my area for using small light duty things to do big jobs but I almost always succeed at this, just a matter of my preference, such as running windows xp on a motherboard that is designed only for windows 3.1 or at most windows 95, but thats another story for another time (and another message board)

Sorry for the increddiblly long message, but I just had to give enough information so that you would know that I realize this will require many modifications, and that I am not a complete idiot who plans to do this kind of job with everything stock.

pmohr

iTrader: (26)

Why are you locking the torque converter at such low speeds anyway? You're also lugging the engine, another bad thing.

You're not towing around all of these loads in 4th gear with the TC locked, are you?

Keep the RPMs higher than what you are (basically cold idle), and you'll be fine.

And you've said this over and over again, but you really need another vehicle. You're just going to keep running into problems using a grocery getter as a tow vehicle.

Have you not considered just getting a beater for all of that? Hell, if nothing else, a Maxima wagon would be a much better platform for all of this.

Max-e-MO!

iTrader: (2)

You can lead a horse to water, but you sure can't make it drink....

You have the wrong vehicle for the wrong job, you would be better buying a small pick up (ranger, s-10, hell, even a nissan!!!) , put a camper on it (to carry your computer stuff)and use the car strictly for driving. The truck would only cost 1200-1800, a lot cheaper than redoing the trans again (not to mention the other damage your doing to that Max.).

If your locking up that TC and the fluids getting hot, it's only going to get hotter the lower the RPM. As the conveter turns, it turns the pump, which pushes fluid to the cooler. The higher the RPM, the faster the pump pushes the fluid through the cooler (also unlike the motor, your fans WILL NOT turn on to pull air through to cool the trans fluid - Nissan figured that if it's in lock up, you gonna be going 45-50+, that would bring enough air though to cool the fluid).

Your trying to do something that that car is not designed for on any kind of day. Put it back to OEM, and drive the car the way it suppose to be used for!!! Get a truck for your other stuff!

L0R1DA

Ok after reading this post I felt compelled to chime in...

Why the heck are you locking up your TC manually and prematurely!?

Do you know how a torque converter even works? Do you realize that the TC produces torque multiplication at low rpms and by locking it in this range while lugging heavy weight you are damaging your trans and your engine?

You are fighting your stock TCM for control, and it will always win. The intelligent thing to do in your situation would have been to upgrade your valve body, and maybe even reprogram the TCM (Transgo sells these kits) to produce quicker shifts with less slip in the clutches. Overheated trans fluid, incorrect fluid level, worn clutches, or varnished control valves causing lazy shifts are the cause of your heat issue, not the torque converter, which produces torque multiplication by simple fluid dynamics between the impeller and the stator, without any friction (heat).

1) Remove your crazy jerry-rigged TC lockup connection and revert to stock
2) Upgrade VB and/or TCM for crisp shifts
3) Your radiator already has a built in transmission cooler so a HUGE auxilliary cooler is going to mess with your fluid pressure and aggravate your problem... I haven't seen a pic of it but from what you've described, I'd ditch it in favor of a more reasonably sized passenger car cooler without the thermostatic gizmo

Sounds like these transmission shop guys you are taking advice from are taking you for a long ride that ends with you back in their shop for another expensive job IMHO...

Max-e-MO!

iTrader: (2)

Now here's a person who knows (probably done it) the proper way to set up a trans for the job!!

My hats off to you sir (or madem), for finally putting into words what everyone else's mind has been screaming.

Makes me wish you work for my company in customer service, knows what your talking about and knows how to describe how to correct it right, THE FIRST TIME!!!!

Thank you!!

txe5502

I am locking my TC because the TC generates heat, which I would like to try to reduce.

Yes I know how the torque converter works, I am working on a mini hydroelectric project and I have disassembled several torque converters to get the turbines out of them. I am very interested in and study hydraulic turbines.

I figured the engine in my car would have plenty enough low end torque for the low RPMS, it seems to have quote a bit of low end torque. As for the transmission, I have noticed it seems to slip at low RPM if the TC is locked so I think you are right about tranny damage, that's why I have been keeping it in lower gears lately.

That sounds like a good idea to me too, I will look into the Transgo kits and see what I can do with that. Also, what valve body upgrades do you have in mind? Something like a shift kit?

I check the trans fluid regularly and it appears to be in good shape, still bright pink. The fluid is a little bit high, so I think I will drain a tad bit out and see what that does for it. The clutches are brand new, just got it rebuilt a little over 2000 miles / 2-3 months ago. What do you mean by varnished control valves? I understand that lazy shifts can cause the clutches and/or bands to slip too much between shifts which could produce massive heat under load, but this heat even occurs while remaining in 3rd gear, which is why I think the TC might be one culpret.

Yes I realize there is no friction, but there is fluid drag, also I realize there is heat produced by the TC as when there is energy going in (up to about 2300 RPM stall) but no energy coming out (about 0 RPM) that energy has to go somewhere, the only place to go in this case is heat losses.

Hmm, would it not be better in my situation if I just manually shifted and kept the RPM high but using straight gears instead of a heat producing torque converter?

As I said before, sounds like a great idea to me

The aux cooler should not mess with fluid pressure as liquids do not compress like gasses, they just flow.

The trans shop (who is the oldest tranny shop in town with several rewards from the Better Business Bureau for doing honest, satisfying business and not a single complaint against them and who has many many customers who say they did a great job, and who often even covers people free of cost even when their warranty expired a few months or a few thousand miles ago (per other customers I have talked to)) told me that with my situation a regular passenger car cooler would not do the trick, and that the TC that came out of my car when they rebuilt it was golden brown (and blue in the center) (overheated big time) was the cause of failure (and yes, I saw it come out). They told me my transmission should be able to do what I am throwing at it currently if some modifications were made to it (and no THEY did NOT give me the idea of the TC lockup mod, I came up with that myself, knowing TC heat was the previous cause of failure)

I have also noticed something in the factory service manuals. The Nissan Quest van DOES have an ALMOST identical transmission to the Nissan Maxima, HOWEVER, the TCM is different, entirely different shift patterns, different TC lockup speed, slightly lower diff gear ratio, and most importantly as far as heat goes, lower TC stall speed. I think maybe your idea of valve body upgrade and TCM reprogramming is a great idea, but I also think since I have higher stall speed (which produces more heat) I should program the TCM to lockup the TC as soon as possible when OD is off, while also utilizing shift patterns which allows the engine RPM to always remain above 1500.

txe5502

Originally thats what I was doing, these days I am locking the TC and manually shifting to keep RPM high

No, I use O/D OFF I know heavy loads are very bad for the O/D gear, 3rd gear is what I use for this.

sounds like a good idea to me, though I think the TC lockup, a little reprogramming, a VB mod, and a cooler are still necessary because I kept the RPMs high before Jan09 and still fried it.

This car IS an old beater



(believe me you REALLY can't see just how bad it is in this pic)
Thats why I am slowly but surely rebuilding it to fit my needs
It's currently a project car if you will...

Max-e-MO!

iTrader: (2)

Ok, I've got the answer for your needs. I've check with the tech at the company I work for.

What you need to do is take that manual L/U off your trans and have the trans shop put in a converter for the 3.5 motor (2k+ Maxima) It's the some converter, but has a lower stall. It will sacrifice your fuel economy, but will have better pull (especially on hills). You can always put in a lower stall and the computer will not freak out, you just can't go the other way (higher stall WILL throw a slip code). Maybe that can help you out.

pmohr

iTrader: (26)

VQ35 is 02+

And just because I already had these images made up a long time ago:

A32:


A33:


A33B:

txe5502

Ok, Max-e-mo, what you said makes sense. I have researched this transmission alot, and what you said about a lower stall speed definately makes since because those minivans which have the RE4F04a transmission DO have a lower stall speed (1800 RPM) and the transmission shop DID tell me more stall = more heat, so thanks for that. I just hope I can afford a converter swap.

BTW I have already removed the manual lockup switch long ago.

Thanks for the help, I will get back with you after I contact the shop, but if you come up with any other helpful information before than please dont hesitate to post it.

L0R1DA

[QUOTE/]The aux cooler should not mess with fluid pressure as liquids do not compress like gasses, they just flow.
[/QUOTE]

O rly? States of matter 101 : a liquid takes on the shape of its container. Why do brake lines have consistently even diameters and why are they bent without kinks? Liquids don't compress (even though, trans fluid does often acquire air bubbles and moisture over time) but pressure accumulation takes time, the amount of time it takes changes based on the path the fluid has to travel. So when the pressurized fluid hits your huge aux cooler, a pressure drop occurs, before continuing on its path. So your huge aux cooler WILL mess with fluid pressure. Just wanted to clear that up for you.

Max-e-MO!

iTrader: (2)

Oopps on the 2002, the jist of what I was meaning (yes I know your a sticker for the details), that the converter for the 3.5 WILL fit behind the 3.0 (A32) and WILL stall lower (due to the multiples of the lower HP 3.0 motor - pmohr see pg 208 of the book I sent you regarding K-Factor under Glossary)

The Stall Torque Ration (STR) is matched to engine torque, vehicle size, final drive, and sprocket ratios. The engine torque from a 3.5 will produce a 2500-3000 stall on a converter due to the torque of the motor. Where as the same converter installed behind the 3.0 motor may stall 1750-2200 (just a guess - don't have all the number to calculate for sure). Pmohr might be able to figure this out with actual numbers due to his vast treasure of knowledge on the Maximas.

My general rule when I've got a customer looking for a specialty stall converter is the higher the horses the more likely the higher the stall.

Add a blower or turbo to a motor and leave the same converter in it, and you stall WILL change to a higher stall.