Engine Cuts out when A/T put into Gear

[marco2379]

Got a tricky one for you guys, I have a 1990 Max SE (163k miles) that cuts out completely whenever I shift the auto transmission into drive or reverse. It starts just fine and idles normal in park/neutral. When the engine is cold it will sometimes idle down very rapidly and cut out and occassionally bucking at about 200 rpm before cutting out. I have been able to lay on the gas with the engine cold and get it to stay on while in gear but it gets no more than 500 rpm but the engine bucks like crazy - then if I shift it into neutral and let off the gas the rpms shoot up to 1700 - 2000 rpms for about 10 seconds before coming back to normal (750).

When the engine is warm it cuts out when shifted into reverse instantly. All dash lights stay on as if I turned the ignition on without starting the engine. Check engine light does not flash nor do I get any codes from the ECU. Fuel Pump and TPS have been replaced to no avail. No vacuum leaks either. Timing belt/chain replace 8k miles ago. Is the transmission somehow connected to fuel delivery? Maybe its not getting the signal to keep sending fuel while in gear?

I've never seen anything like this before. Please help? This is my first Maxima (I'm a Saab Lover) and its ruining the experience already.

[NISTECH]

I think I responded to your post in max tech. but By your description I wanna say your torq convertor is locked up. but you shouldnt even ba able to keep it running in that instance. check around the shifter cable and see if it is hitting any connector on top of the trans.

[marco2379]

Yes I remember your reply from the Tech Forum (Not trying to flood the forums, just trying to find someone that may have experienced this before). Torque Converter Lock Up? I'll look into that as well as check the connectors around my transmission. The transmission ran just fine before I accidently pulled and put back the fuel pump fuse with the car running. Please share any ideas or possible remedies. Thanks.

[marco2379]

Can I unplug the torque converter lock up connector somehow to test the theory of the converter lock up? Which connector should I be looking for?

[NISTECH]

No cause if it is stuck on it is mechanically stuck and unplugging it would do nothing. Keep in mind I have never seen it happen on a nissan. At least not here in california

[marco2379]

Well if it was not stuck before and the only variable that changed was the pulling of the fuse, would that be enough to cause that drastic of a change with the torque converter? I tend to think its an electrical problem just because the fuse accident? Should the ecu/fuel pump send a different amount of fuel in reverse/drive than it does in park/neutral?

[NISTECH]

yes the ecm does slightly increase the pulse width of the injectors from about 3.2 ms to approx. 4.0 ms to compensate for the load of the trans when in gear. There is not enough of a loss though when putting it in gear to kill the engine if it didnt make that adjustment. Your fuel pressure never changes unless there is a vaccum loss to the pressure regulator. The standard idle pressure is approx 36psi when the vaccum line is removed from the pressure regulator the pressure increases to approx 43psi. This occurs only when you are accelerating from a stop and the vaccum in the intake system drops below 5"Hg. So putting your car in gear should have no effect on fuel pump supply.

[NISTECH]

I just thought of a way you can determine if it is the torque convertor or engine problem. Get the front end of the car up on jack stands so the tires are off the ground. Get in the car and put the shift selector in N. Start the car after the car reaches a stable idle without stepping on the brake or the throttle drop it into D. If the wheels start spining and the car continues to idle let it roll for a few seconds to stablize then gently start applying the brakes as if you are coming to a stop on the road. Does the car act like a manual trans in first gear coming to a stop without the clutch being in? [ Does it buck and jerk till it dies] If it does it is because the torq converter is locked up.

[marco2379]

Okay I have to edit my post, I re-conducted the troubleshoot you suggested just as you explained and the rpms go down when the brakes are depressed with the car in gear. If the brakes are applied 100% the engine cuts off. So I would now have to agree that my torque converter is locked up. How could this have happened? Is there a way for me to unlock the torque converter without pulling out the transmission?

[NISTECH]

does it feel like a manual trans in first gear with the clutch released and hitting the brakes to stop. Did it jerk and start pinging untill it died?

you have a control problem with the solonoids most likely. You can acces the solonoids by removing the pan and possibly removing the valve body. I strongly recommend you get a service manual on your car so you do not remove unneccesary parts from your trans when you take it apart as it will be very difficult to put it back together. You will likely need to replace a solonoid. If you are not comfortable going into the intricate operational components of your trans I dont recommend you do this yourself but rather have a trans shop do the work. It would be wise to conduct some line pressure tests on the trans before tearing into it. I know its probably not what you want to hear but This type of work almost needs to be done by a trans specialist.

[marco2379]

Well it just drops rpm's in direct relation to the amount of brake pressure applied until it cuts off. The only "pan" i see on my transmission is actually on top with an overflow hose connected to it, is this where I need to look for the solenoid? What about the valve body? Do I need to pull the transmission to get to these internal parts?

(I just put the transmission in myself a week ago and its a pain that I'm trying to avoid doing again so soon).

[NISTECH]

it is under that pan on top of the trans.

[NISTECH]

dont do this without the service manual or you could damage the trans internal parts.

[marco2379]

Okay, now I have changed the solenoid and I gave it the same test as before, the results - I can now put into drive and depress the brake slowly without it cutting off. However the idle drops to around 500 rpm in gear with the brakes fully applied. If I hit the brakes to fast the car will drop rpms to fast to recover and cut off. Any ideas on how to get/keep my rpms up in drive/reverse with the brakes pressed?

[NISTECH]

have you drained and refilled the trans with fresh fluid yet. Its possible you have debris in the fluid passeges and that is what caused the problem to begin with. It doesnt suprise me especially since you just put a used trans in there. Did you flush the trans at all once you installed it initially?

[marco2379]

I did not flush the transmission at all, I have heard so much about how transmission flushing is the step done just before transmission failure that I was afraid to. Should I just drain it or should I do a power flush?

[NISTECH]

if you have alot of miles on it just do a drain and refill. You are correct power flushing it could lead to catostophic failure of the trans. It has happened a couple times to us when we did a trans flush on a high mile trans.

[marco2379]

Okay then that part has been handled because I spilled all the transmission fluid just trying to install the transmission. What do you think about putting in another torque converter? Is it possible that my converter has just gone bad?

[NISTECH]

it is possible. not sure thats it though. checking your line pressures is really the only accurate way to see whats going on.

[marco2379]

Okay, Today I re-checked my transmission installation and found that the torque converter was not fully on all the gears when I installed it. So I reset the converter refill the spilled transmission fluid, and...it worked briefly, I could be in drive and hit the brakes with only minimal rpm loss. I tried it again and then it went right back to cutting off/stalling with the brakes applied. How do I go about checking line pressure and what tool is needed?

[NISTECH]

You may be able to loan one from auto zone. The good ones have 3 guages on them to give you all your readings. You need to tap into the small ports in the side of the case blocked off by screw in plugs.

[marco2379]

I'll try that, I'm also planning to swap transmission computers, and check the air flow meter. I think I might need to revisit the vacuum leak check because I do hear minor hissing in the engine compartment on the drivers side but I can't figure out if its the air intake or a bad hose. By the way, what pressure should the transmission read when I check line pressure?

[NISTECH]

I was trying to find it today on all data but was unable to locate the specs. Our dealer is only 5yrs old so we only have manuals back to 94 and I dont know if the 94 J30 max has the same specs as a 90 J30 max.

[NISTECH]

BTW I am avoiding the obvious fact your trans pump could be damaged from the converter coming out. Just because logically the problem that would stem from that would be quite a bit different then what you are experiancing. I am working on the assumption it did not do any permanant damage to the pump.

[marco2379]

Hey Nistech,

I just would like to thank you for all of your diligent assistance and extremely helpful pointers. Today I swapped out the torque converter in the maxima and it solved the problem. Thank God. I appreciate your help 110%.

[NISTECH]

I am glad to hear you got it fixed.

[marco2379]

Well NisTech,

Looks like the problem resurfaced again, it worked then it went back to doing the same thing after driving it. I'm ready to give up on it, just hate to waste its perfect body and interior.

[NISTECH]

Are you sure that transmission is for that car? I mean 100% sure?

[marco2379]

Before making the swap I checked my parts car and the problem car and they both list the same transmission #, both trannies are identical in dimensions, bolt placement and electrical connections. The transmission is from an 1989 GXE. It seems as if the either a lack of pressure or too much pressure to allow the torque converter to unlock, not sure which it might be. Any more suggestions?

[NISTECH]

for this problem to be gone then suddenly resurface seems like a control problem. maybe electrical short to the torq conv solonoid? the come and going nature of this is so charicteristic of an electrical malfunction. I am running out of ideas. I think your best bet is going to be line pressure checks to see whats going on with the controls.