I did a pan drop, filter change and new fluid (with a bottle of LucasOil trans treatment) and it seemed to make a big difference.

Make sure to clean out the pan and remove the magnet and clean it well.

Add a link to NICOclub to your site!

...even the HITMAN is on MySpace

Stacey Lynn Childs 1970-2007... Love of my life, my best friend, Heaven's prettiest angel. I miss you so much.

It accomplished nothing.

Mine slips approx 10 minutes into driving it (from a cold start), and once it quits slipping, it drives fine (until it gets cold again, then starts all over again).

Pulling the autotrans for a manual swap in 2 weeks, auto rebuild too expensive.

We have some great "tech days"!

I know it's a lot of work.. but it would be very cool if you did a pictoral how-to guide for everyone else to follow in the future. I have seen other's do bits and pieces with pics, but never a real good step by step tranny swap guide.

just an idea.

Good luck with the swap. Nice to see another SHIFT---Convertible around.

http://www.240sxconvertible.com - The internet's only 240sx 'vert site!

Joshua 1:9 "Have I not commanded you? Be strong and courageous. Do not be terrified; do not be discouraged, for the LORD your God will be with you wherever you go."

I have a HB and it doess the exact same thing. Myself and others have been trying to figure it out on the tech. fourms but we have come up with little. We think it is electrical most likely a short or bad sensor. I don't think anyone has yet to figure it out, but the throtle positioning sensor and speed sensor might be part of the problem. Good luck!

Throttle position switch adjusted with minor improvement. Flush improved all other shifting characteristics but hasn't cured the base problem. I'll report any significant progress..........if it occurs.

Down to the exact timing....

I swapped to a 5-speed, thniking I had a bad trans.

I have the exact same problem to the "T" as everyone else here in this forum with this auto tranny! I'll be waiting to hear back from you. Thanks!!!!!

240rocker

This weekend, while driving my car, I'm going to hopefully get the car to exhibit this shift occurence and when it does, I am going to try and get the codes out of my ECU to see where it might be failing.

I have had this problem for about two and a half years now and I have taken it to two different Nissan dealers and of course it wouldn't act up on them so I never got anywhere with them. One dealer did a $160 tranny flush and the other dealer charged me $35 to drive my car for an hour. I had a transmission shop look at it also and it never acted up for him either, but he suggested that maybe the TPS was bad so I replaced that too.

Does anyone here who knows anything about the TCU think that maybe this could be the culprit? I work with electronics everyday and I know how picky some circuits can be when they go thru temperature extremes. What exactly does the TCU do? Does it actually tell the tranny when to shift gears? I found a place in Florida that repairs and sells these for around $250. Someone else also mentioned that maybe the 1st to 2nd solenoid in the tranny could be flaky. I talked to another transmission shop the other day and he told me that if it was the solenoid it wouldn't be bad at all to replace. All you have to do is drop the pan and check the solenoid and replace it if it's bad.

OK guys these are the things that I'm looking at and as I find out more info I'll let you know.

Oh...and I could very easily put a 5-speed in, but I really want to know why this is happening to our Auto tranny's. I am determined to find out.

I'll keep ya posted and anymore info you can offer would be great too!

Thanks!!!
240ROCKER

240ROCKER

Another question I have is if I take off manually in first gear will the car automatically shift into second as it approaches red-line even though I'm in first?

Mine would rev to the rev limiter (I feared damaging the motor).

Manually leaving the car in first will hold it there.

I have been taking mine to shops in my area, but no one knows what is the matter with it.

Recently I had an episode where my car didn't shift. I shut it off and restarted it, but this didn't work. I tried again and got it to shift. Ever since that bad episode it shifts kinda hard and makes a whining noise at low speeds. I am about ready to have the transmission rebuilt. I guess 2 years of this problem has taken it's toll on the car. I wish I could figure it out!

The valve body has all sorts of control valves and springs and is a very expensive part to replace, which is why most tranny shops don't rebuild or replace these.

I have learned that more than likely I have a stuck control valve in the valve body and the reason that I normally don't have a problem in colder weather (50° or lower) is because there is more pressure being built up in the valve body to compensate for the colder temps. and when it's warmer weather, the pressure isn't as high and therefore one of the control valves that pertains to the 1st to 2nd shift is getting stuck. I was told that an additive called "Transmedic" might unstick this valve. It will take about two to three weeks to really get into the system, but that it might keep that control valve from sticking.

What are your thoughts on this?

240ROCKER

Modified by 240ROCKER at 1:03 PM 3/1/2005

The thing is, my car repeatively has issues shifting into 4th also.

Is there one valve body, or are there multiple ones that control different trans functions?

The lower body of the valve body has these valves in it: Servo charger valve, 3-2 timing valve, 1st reducing valve, Manual valve, Modifier accumulator valve. So as you can see there are a bunch of valves in this very intricate part and this is more than likely the cause of our shift problems. One of these valves is getting stuck and not operating properly.

I'm going to try this Transmedic additive made by GUNK and I'm going to see if this fixes my problem. I will give it a few weeks and see what happens.

240ROCKER

Thanks for the info!

I'm curious to know if 240Rocker's ECU codes have yielded any clues as to what the problem(s) might be...

It is my understanding that you need to pour the entire bottle of Transmedic in your tranny and wait a good two to three weeks to get in your system.

Has anyone used the new Dexron III in their auto tranny's yet? I have also read on other forums that this might possibly fix tranny problems as well. There are so many possible solutions out there. I just wish we could find one that everyone is in agreement with!!!!

I'm still determined to get to the bottom of this!

240ROCKER

Modified by 240ROCKER at 1:10 PM 3/2/2005

The only thing I might have done wrong was not leaving the Seafoam in the transmission long enough.

First off, I removed the kick panel so I could get at the ECU so that I could see if it would give me an error code. It did not. It gave me a code of '55', which means no error.

Next, I went and talked to a auto tranny specialist here and we talked about this shift problem in great detail for over an hour. He was very informative. He seems to think that this is definitely an electrical problem and not a mechanical one because of the fact that it always happens during the first 5 to 10 minutes of a cold start.

He advised me to splice an LED on the wire that goes to the Shift solenoid for D1 to D2 (this is pin 6 of the TCU). I believe the service manual calls it Solenoid "A". Tie the other end of the LED to ground. Make the wires long enough for the LED to be in plain site while driving so you can see it for this test.

When the car is operating correctly, and the car is still in first gear the LED will be 'ON' and when it shifts to second gear, the LED should turn 'OFF'. Now, if the car doesn't shift into second and you are above 37 MPH, look at the LED as it should be off. If the LED is 'ON' at this point, then the TCU is bad. If it is 'OFF'and your car hasn't shifted yet into second, then more than likely you will have a bad shift solenoid for D1 to D2.

I told him that I had read that on other forums that replacing the valve body was a fix that some people had tried and worked. He told me that the reason that was probably a fix is because more than likely, when the valve body was replaced, so was the solenoid because it is attached to the valve body.

The reason that we are seeing this intermittent shift occur during the first to second shift interval is because this solenoid is used more than the other solenoids. However, in time the other gears will more than likely behave in this manner, which means that the other solenoids will eventually go bad too.

I haven't hooked up the LED yet. The TCU is a little bit further up in the dash and so I really haven't had time yet to unbolt it from the frame. I'm doing that this weekend, so when I get the results of the LED test I'll let you know. If the LED is 'OFF' and the car doesn't shift, I'm taking the car to my tranny specialist and he is going to remove the D1 to D2 solenoid and test it in a heat exchanger to see if it is operating properly.

I'll let everyone know as soon as I know...!

240ROCKER

Great info!

At startup from cold, the transmission shifted properly and the LED's behaved properly, that is: A+B lit for first gear, B only for second, none for third, and A only for overdrive.

I stopped and started until it hung up in first gear, staying in first all the way to redline (where I backed off) without shifting. During this hangup, both LED's for A+B stayed lit, indicating that the TCU was telling the transmission to stay in first gear.

Unfortunately the hang up only occured once and the next (and all following) stop and start operations shifted normally and the LED's behaved normally. I intend to try this again tomorrow once everything has cooled down. I would like to replicate the "hang up for a while but then shift" pattern I sometimes get.

But by your mechanic's analysis this would point to a bad TCU.

TCU's sound expensive, so there is one more thing I am checking. The transmission has a fluid temperature sensor in the sump, a resistor whose resistance drops as the fluid temperature rises. I measured the resistance when cold (65 degrees in the garage) and it was 2560 ohms versus the manual's standard of 2500 for 68 degrees. I took another reading when warmed up and got about 600 ohms (no range is given in the service manual). I will try to rig up a way to measure this resistance on the fly so I can watch the multimeter to see if the resistance drops smoothly as the fluid warms up. Not sure what I'm looking for but I would certainly expect the change in resistance to be smooth. We'll see.

I sure would like the temperature sensor to be the culprit since it looks cheaper and is easily changed (drop the pan and it is right there.)

I wish I knew the computer logic (how it integrates throttle position, RPM, fluid temperature, and probably some other inputs) to decide when to deactivate Solenoid "A".

I'll look for your results and report mine when available. But in the meantime we might start searching parts stores and junkyards for replacement TCU's............

240ROCKER

I have read here and on other forums that they changed the TCU out and still had the same problem. I'm wondering if people got confused, and changed out the ECU, thinking that they were changing out the TCU. I know I made that mistake at first when I started looking for pin 6 and realized that the color of wire was not what the service manual indicated. The ECU is the very first box that you see when you remove the passenger side kick panel. The TCU is further up into the firewall behind the blower motor. It ain't no picnic to get out either!!!!! lol

I'll post back again tomorrow after driving it a while.

240ROCKER

I took resistance readings on the fluid temperature sensor at hourly intervals as the fluid cooled down. Resistance seemed to climb smoothly back up to 2.5K ohm range. So I'm doubting my hopeful theory of a bad fluid temp sensor.

But.......if the problem develops when the resistance drops to a certain level you could splice in a resistor and keep the signal from ever dropping into that range. Not sure what that would do to shifting patterns however. I'll mull this over some more.........

Of course there is one very easy fix that won't cure the problem but would make it easy to overcome. You could put an interupt switch on the power supply to the TCU. At every hangup just flip the switch on and off and reset the computer. Same cure as turning the engine off and back on but quicker and easier on the starter.

The saga continues.

The transmission shop had it for three days tring to get it to act up and of course it didn't. In fact, he said that this tranny is in very good shape to have 149K miles on it. He said that the tranny is shifting great in all gears and that he couldn't detect any malfunction whatsoever and he has been in the business for thirty some odd years and he knows when a tranny is not behaving properly.

He suggested for me to put an LED on the other solenoid as well and see what state it is in when the shift problem occurs. I noticed that ncaa1969 has already done that and he reported that both LED's were on at the same time which means the tranny doesn't know what to do so it stays in 'limp' mode. This is where the tranny will still run but only in first gear. My tranny specialist said that if both LED's were on, than there is some bleed over from one solenoid to another which is caused by one of three things.

First, if when the problem occurs glance at the speedometer and see if there is some erratic movement back and forth of the speedometer needle. If there is erratic back and forth movement then the Speed Sensor is faulty. It is mounted on the side of the tranny. Second, if the speedometer is OK, then there is a wire somewhere in the main harness that has some of its insulation rubbed off and is somehow shorting to ground or a wire that goes to ground is loose. The third thing he said to check is all the interconnects between the TCU, ECU and tranny. It's very possible since these interconnects are right near the battery that there is some corrosion that has gotten inside one of these connectors causing intermittent connection. He suggested pulling them all off one at a time and give them a real good cleaning with contact cleaner.

My tranny specialist told me that he is nearly 100% sure that the tranny itself is just fine and for me to start looking electrically.

I told everyone from the beginning that I was going to find out what was causing this and I'm just about there.

This guy spent nearly four hours with me on this problem the last few days and I asked him how much I owed him for his time and he told me to "put my money away", that he was very happy to help me out as he wants to know what is causing the problem too so that he can file it in his database.

240ROCKER

I've been monitoring the voltage output of the fluid temperature sensor as the car warms up. The voltage drops normally from 1.6 volts to .48 volts and the hang up in first gear happens when the voltage is in the .75 to .8 volt range. Still no idea what that means, except that the hang up occurs at that voltage signal and accompanying fluid temperature.

I'll try the contact cleaner on all connections. Can't hurt. Might help.

I have no flicker of the speedometer, perhaps ruling out the speed sensor.

Quote, originally posted by NismoDriver240 »

When you own at the track what are you going to say? "oh yea dude I just bought this car" any schmuck with money can get a fast car, but it takes skill and reaps respect only when you build it yourself.