Symptoms:

1. After starting the engine, if shift the gear from Parking/Neutral to Drive/Reverse, idle speed drops sharply to 200 rpm. Sometimes engine stalls immediately. Sometimes the car shakes a lot without stalling for a while and the idle speed jumps back to 500 rpm. But it still shakes at 500 rpm. Depressing the accelerating pedal to maintain the RPM when shifting the gear from P/N to D/R helps to let the car start going without stalling. However, it is dangerous since the car starts going too quickly with accelerating.

2. If shift gear from Drive/Reverse to Parking/Neutral, the RPM surges to 1500rpm and drops slowly to 900rpm. Looks like the car is taking a deep breath.

3. In driving, if hold brake at stop signs or red lights, right before the car stops (RPM decreases to 600 rpm), the RPM suddenly surges to 1000 rpm momentarily and drops immediately to about 200 rpm. Sometimes engine stalls immediately. Sometimes the car shakes a lot without stalling for a while and the idle speed jumps back to 450 rpm. If hold brake very gradually to let the car stop slowly, the RPM still surges and then stays at 450 rpm. The car shakes a lot at 450rpm.

4. Shifting the gear to Neutral at stop signs helps avoid the stalling problem. But it is still very often that the car stalls when shifting from Neutral back to Drive when the green light is on.

5. When weather/coolant is cold, the car is more likely to stall in above situations.


My 91 maxima (153K) started to have this problem three weeks ago. I took it to a nearby body shop. They charged $30 for diagnosis and told me that one fuel injector was not working so the idle speed was so low. At the same time, they said two other injectors were going to fail soon and suggested me to change all the three injectors for $500.

I followed their suggestion because I was in hurry to get my car fixed. However, after they replaced the injectors, the problem was still there though the car didn’t die at that moment. After I took it back and run for several days, the above symptoms showed up again. I took the car back to the body shop. They told me the Coolant Temp Sensor and Idle Air Control Valve were not working either. They asked $400 to replace them. I refused and took the car back. Then I bought a new Temp Sensor and a used IAC valve from junk yard then replaced them myself. However, the replacement didn’t help at all.

After a lot of tries, I finally took it to a NISSAN dealer. A tech tried to drive my car to garage and the car stalled when he shifted the gear. Then he took a quick look at the underhood and concluded my transmission is over. His diagnosis was “Torque Converter inside transmission locking up. Advise replacement of transmission to correct”. Then this tech told me to trade-in my car to him for only $200. That made me suspect he might want to take advantage of me and I also started to doubt his conclusion on my car. I asked him there is any way to keep this car, for instance, by replacing the converter only. He told me my car won’t last more than two weeks even after replacing the converter and the best way for me is to discard this car.

Right now I have no idea what to do since I am so unfamiliar with this converter stuff. Could anyone here give me some suggestions? Thank you very much. Should I give up my favorite maxima? What is “converter locking up” supposed to mean? Is there any way to unlock it? Thanks a lot.


BTW, recent repairs for this problem were listed as:
 Changed fuel injectors (totally 3: No 3, 4, 5)
 Changed air filter
 Adjusted idle speed
 Changed PCV valve
 Changed Distributor Cap, Rotor
 Cleaned Throttle body and IAC-AAC valve
 Changed fuel filter
 Changed Coolant temperature sensor
 Tried changing IAC-AAC valve and air cut valve. It didn’t work so returned to the old parts (used parts from junk yard)
 Checked Spark plugs, Spark wire resistance
 Tried changing Throttle Position Sensor (TPS). It didn’t work so returned to the old parts


I am sorry for this long story. I really appreciate it if anyone can give me some suggestions. Thanks a lot.

 

sounds like it's your tranny, but a new car will cost you more than the the reapir. plus, assuming the car is in even halfway decent condition (minus the tranny), you can get more than $200 for it. 10 to 1 the tech was trying to screw you over - good catch.

first, when you say body shop, you really mean a mechanic right. Why on earth are you going to a body (shop that fixes dents in the car) to do normal diagnosis and repairs.

how was this place diagnocing the bad injectors and iac stuff. it could cause your fluctuating rpms and stalling, but since this is mostly happening when you switch gears, I'd look into that first. plus, since it's fine in park/nutral, the tranny is very likely

go to http://www.aamco.com/main/promotions...romotions.html and get a free transmission diagnosis coupon and get the tranny checked out.

 

Thanks a lot for your reply.
Yes, the body shop also do mechanical repairs though their major job is body work. I went there because it is very close to where I live. This was my first time to be there and will be the last time too.
My old maxima has 153K miles on it. If it will cost me more than $1000 to get it fixed, I'd rather buy a new one. But before I do that, I want to make sure there is no ways for me to keep it.
It is ridiculous to trade-in my car for $200 after just spending $500 on it. Most parts (the drive axles, the muffler, the flexible exhaust pipe, the alternator and battery, etc) on my car were almost new since I planned to use it for at least two more years.

What does "Torque converter locking up" mean? Is there any way to unlock it? Thanks a lot.

 

If hte "lock-up torque converter" is really at fault, as the Nissan mechanic says, that's very repairable, shouldn't be too expensive, and by no means whatsoever means that the car has to be replaced. The torque converter has an electric solinoid which locks the torque converter in top gear. Sometimes when they get old, the solinoid will stick on. What you can do as a test, is disconnect the lockup feature. I'm new to Nissans, so I'm not sure where exactly the wire is, but maybe that's something you can find on your own. You should be able to unplug it and at least make the car driveable, until you decide to fix it. That's assuming of course, the reason that the torque converter is "locking" is due to the lockup solinoid. However, I can't think of anything else in the torque converter that locks.

That's assuming of course, that's what the problem is. It could be something else entirely, that both of these mechanics haven't found. ususally when there's something like that, that's not working properly, I like the mechanic himself to show me why he figures that's the problem. If he's a good mechanic, he'll take you into the garage, and show you why the part isn't working properly, maybe even with the car hooked up to the computer. If he's not willing to do that, then take your business elsewhere. Also, it's good to get a guarantee from the shop, that the repair will fix the problem. If they're really sure about it, and willing to hold their reputation up with a guarantee, this means that if by some chance, they don't fix it right, you have something to go back on. I had a Pontiac Grand Am before my Maxima, and the dealership replaced all the fuel injectors, insisting that's what was causing the problem. I had them guarantee it, and sure enough, that wasn't the problem. Then they thought it was the valve lifters, this too was false, however they insisted. Finally they found a very small crack in the crank position sensor harness which was causing all the problems. I ended up paying for the injectors, but I got the valve lifters (which didn't need doing), a new crank sensor harness, and a loaner car for the week at no cost to me. I'm not suggesting that you use this as a way to get free repairs and a loaner car, just that with a guarantee, you have something to fall back on

 

its probably NOT yout torquw converter at all.

u say this happens most often when the coolant is cold? this could be the coolant temperature sensor. You didnt have to change the injectors...a bad injector or two wont make your car idle so low at 500...the idle speed is 750rpms and even with a bad injector it will idle at the right RPMs. u can get a new coolant temperature sensor for around 19-20 dollars, a bad sensor can cause erratic RPMs, i experienced it personally.. its cheaper to try and change that and see if it helps rather than spening 500 on it...or try to get a free computer diagnostic done at an Autozone...see what codes come up.

 

I think your idle system on the engine is the problem. It is sometimes idling too high
(the rpm is ok with the load of being in drive
) but gets too high in neutral. Othertimes the engine is not idling high enough. For a low idle, I'd say clean the TB, it is probably dirty. Try fuel injector cleaner. And either clean up the idle air control valve, or more appropriately, get another one. I would think TPS could have been bad, and caused too high of an idle, but you said replacing the part didn't do anything. After reading your problem again, it really seems that your idle is not working well enough, to keep the car from stalling. I would think a bad fuel injector would cause more roughness, but maybe someone can add their thoughts. So 1) fuel injector cleaner 2) clean TB 3) new idle air control or clean IAC 4) Try TPS again 5) spark plugs/wires/rotor distributor. Sounds like you've down some of these things.

 

Thanks for your reminding.
But I did change the coolant temp sensor. The problem is still there one week after I did the change. The check engine light doesn't come up so there is no error code can be read.
I agree with you that one bad injector won't cause this problem. I should have been more confident to say that when that body shop insisted it was the injector.

 

Thanks for your reply.
I actually have done all those but the car still has that problem.
The idle speed was adjusted to be 900rpm by me to try to avoid this stalling problem. But it didn't help too much. The previous idle speed was 700rpm which is supposed to be right.

 

Thanks, Creedence85:

I think what you said makes perfect senses.
Just now I took a quick look at the Auto Transmission Control Unit (TCU). It is above the ECU and has a similar appearance with it too. I had a difficult time trying to unplug the cable at terminal 5 (sb told me it is the lock up feature cable). Those terminal cables are grouped together as a single plug. If I unplug it, all cables will be disconnected. So, can you give me some hints how to do that? Is it possible to disconnect the other side of the cable? But I have no idea where this cable goes to.

Thanks,

 

Maybe make sure all of your electrical grounds are well grounded. Otherwise, test the tranny. Good Luck.

 

RE4F02A=worst nissan A/T ever. I hate mine with a passion.

 

Buddy, it sounds like you've had quite an adventure and been taken for
a ride in the Twilight Zone. The Diagnosis of the Torque converter locking is your most probable cause. If your converter is locked
your engine is directly tied to your trans and it's just like stoping a 5-speed
without disengaging the clutch. I would'nt suggest modifying the ECM
connector, It could cause more problems. I'd suggest you try replacing your
soleniod pack. It's right under the trans pan and easy to get too. Sometimes the solenoids develope intermittent shorts and internal problems. Your problem
is definetly trans related. I'd recommend you try that first. The part about
trading your car is B.S... If your car is in decent condition 150,000 miles
is nothing, it can last a lot longer as long as you change your oil and timing belts
when recommended. It's worth it to get the car fixed. Not to sound like a know it all but I'm a nissan tech and from what you described I'd bet a good ***-chewing from the customer it's either the solenoid pack or the torque converter,
respectively. Find a good dealer. Let us know what happens.

 

I figured out where the terminal 5 cable goes. It goes to Torque Converter Clutch Solenoid valve, which, as I can see from the manual, is connected with the Solenoids harness connector as its port G or port 5. So I don't have to disable the cable from the Transmission Control Unit. Instead I can disconnect it from the Solenoids harness connector. However, the same question is how I can disconnect it since it is just one port of the connector. If I disconnect this connector, all the ports will be disconnected. I am not sure what will happen then.
Is it a good idea to use electric tape wrap the male connector to disconnect it? Anyone here has experience? Thanks a lot.

 

check all electrical connections...i had a 91 gxe i brought home from palm springs...months after started doing similar stuff...all the rubber seals dried up and water was causing corrosion on all connectors i also got new injectors. the humidity will eat those exposed connections

 

Today I went to AAMCO for a free diagnosis. This time A tech used a diagnosing equipment connecting to the "check connector for ECCS" under the steering wheel. Looked like he tried to read something but seemed he failed. Then he tried to drive my car. The car stalled as usual when he shifted gear. He then tried to read again. Finally he told me something is wrong inside the transmission so the transmission is tied with engine. I asked him whether it is Torque Converter or not. He said maybe or maybe not. Then he told me that I have to have the whole transmission rebuilt and the cost is $1325 and additional $379 for the Torque Converter.

I then asked him whether it is possible that Torque Converter locking up can be disabled by disconnecting TCU terminal 5. He said "no, that will just destroy your transmission". I planned to try disconnecting TCU terminal tomorrow. But what the tech said made me hesitate. Seems like it is really my transmission dying out. The transmission fluid was already dirty when I bought the car. I have the transmission fluid changed after driving it for one more year. That job was done in Oct. last year.

Anyone know there is any better way to get more than trading-in my car to dealer for $200? Thanks a lot. I am not trying to dig a lot of profit but it should be fair for me to get the $500 injectors replacing fee back.

Almost all parts on my car are pretty new since I have them replaced very recently. New tires, alternator, driving axles, flexible exhaust pipe, muffler, battery.