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Car Forum / Nissan / Nissan Maxima / March 2004Help: dealer said my 91 Maxima is over
Hi, all: The symptoms of my 91 Maxima (153K miles) are: 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. > Hi, all: > [quoted text clipped - 27 lines] > 5. When weather/coolant is cold, the car is more likely to stall in > above situations. Could be the converter in the transmission.. when shifting into D or R, does it really 'thump'? This could be a sign of a dragging lockup clutch in the converter.. if so, it is possible to replace just the converter, not the whole transmission, but the transmission still needs to be removed to access the converter. If there is no excessive 'thump' when shifting into D or R, it could simply be a wiring problem between the Transmission control unit and engine control unit. The TCU needs to tell the ECU when you shift to D or R, so it can open the AAC a bit to compensate for the load. Without this signal, the ECU will still compensate eventually but will cause the RPM do drop sharply before recovering.. also will cause the RPM to rise when shifting out of D or R, and again it will slowly compensate. Hope this helps. Greg. Hi, Greg: Thanks alot for your reply. As I can see, there is no "thump" when I shift from N/P to D/R. The shifting is smooth except the engine may stall. The car is perfect when the RPM is above 700. The problem only happens when shifting gear or stopping at stop signs. Another symptom is sometimes when I take my feet off the accelerating pedal on highway with 60RPM, I can feel a little bit of immediate slowing down like holding a little bit brake. I didn't have that feeling before. So it is possible that only the wire is broken between ECU and TCU? If so how to check it and fix it? Thanks, you let me see a gleam of hope! > > Hi, all: > > [quoted text clipped - 45 lines] > > Greg. > Hi, Greg: > [quoted text clipped - 11 lines] > > Thanks, you let me see a gleam of hope! I can't help to much with wiring diagnosis on the ECU to TCU, perhaps posting on maxima.org might give you some info from those who have the knowledge. The 'engine braking' issues also could point to a converter, but I would also expect rough gear changes with a dragging converter. My parents had a similar problem with their Camry, but in their case it was the airconditioner, not the transmission that was causing the problem due to a bad connector. Thanks. Greg. 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 anyone 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, will > Hi, Greg: > [quoted text clipped - 61 lines] > > > > Greg. 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. 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. > 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 [quoted text clipped - 73 lines] > > > > > > Greg. > 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. Is it idling on 6 cyl? What's the comp like? vac leak? Too many posible problems to diagnose over the net.  SignatureSteve http://www.atlantaracing.com 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. 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. > > 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. > > Is it idling on 6 cyl? What's the comp like? vac leak? Too many posible > problems to diagnose over the net. > Today I went to AAMCO for a free diagnosis. This time A tech used a > diagnosing equipment connecting to the "check connector for ECCS" [quoted text clipped - 6 lines] > the whole transmission rebuilt and the cost is $1325 and additional > $379 for the Torque Converter. 2 words, -used tranny-. SignatureSteve http://www.atlantaracing.com > Today I went to AAMCO for a free diagnosis. This time A tech used a > diagnosing equipment connecting to the "check connector for ECCS" [quoted text clipped - 15 lines] > changed after driving it for one more year. That job was done in Oct. > last year. Although I can't help with the TCU pins, you will not destroy your transmission by disabling the converter lockup, unless you plan on doing a lot of highway driving, and an unlocked converter could cause your transmission to overheat. Also, it is unlikely that the problem is your TCU telling the converter to lockup all the time, as there is mechanisms inside the transmission that prevents fluid pressure being applied to the lockup clutch when the transmission is in 1st gear, once it changes to 2nd it can then lockup if told to. If a dragging lockup clutch is indeed the cause, then it would have to be a faulty converter. Greg. |
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