fastasleep

I have a 1999 SE (auto). My attorney has been driving it, and it shut off on him on Saturday. He tried to drive it further, but to no avail. He had it towed here.
The symptoms were as follows:

1. Puffing A LOT of white smoke.
2. Raw fuel pouring from tailpipe.
3. Car would not shut off when the ignition was turned off (it would idle, but not rev).

I am pretty sure I had two different issues. I believe I had a stuck injector (#3) after pulling spark plugs to diagnose. I bought three new injectors and installed them as #1, #3, and #5 just so I didn't have to worry about doing it again in another 10,000 miles.
After getting it back together, I started it and it ran fine for a little while and then began running a little raggedly at idle. The car revved strongly, but would stumble back to a rough idle. The car did NOT spit any more fuel out and after running for a little while and allowing the catalytic converter to get warm, the car quit smoking as well.
At this point the car will start and run but idles a little rough. The car will continue to run after the key is turned off. I can pull the EGI relay when the ignition is off (and the car is still running) and the car will stop which led me to believe I had harness issues, like the B/W wire to the relay was shorted to ground. BUT, I can pull the ECU connector off and it will kill the engine as well which leads me to believe that the ECU is faulty and it is not a harness issue. Also, with the ignition off and the car running, I can wiggle the harness at the front of the engine on the passenger's side of the engine bay and there is no change; it seems that if it was a harness problem the continuity problem would most likely be in this spot and be more prone to act differently by shaking it.
My questions are as follows: how do I determine if my car is equipped with NATS? If it is not equipped with NATS, can I use any other ECU (that has a different part number) in the car without re-pinning?

Here are some pieces of information that may be helpful:

The car is a '99 (built in 02/99)
The ECU part # is A18-N11 Z91
This is a Cali car.
I do not have a list of current codes, but there is one pending; my Matco 4000E can look at all values, but no codes are present. There was a pending code of 1320 (Ignition Signal Primary), so I think I may have a bad coil pack but with the ECU possibly being bad, I want to sort out the "running while off" problem first instead of chasing a symptom of what may be the root cause.

Any info or advice?

Thanks, guys.

-Les

DennisMik

iTrader: (2)

Very strange. To start with, your car has NATS because it is a 1999. No need to check further.

Engines can run by themselves from severe cases of pre-ignition and pulling wires and relays and anything else won't stop that. You evidently have power being sent to the ECU and other things when the key is supposedly off. Under the hood by the battery is a fuse block. When the car is still running with the key off, pull out the fuse labelled "FL30A IGN SW" and see if the engine stops. I assume it will as you have pulled relays and harness connectors. What I am thinking is that the ignition switch is somehow maintaining connection even though you have turned the key off.

Regarding ECUs, swapping to an ECU from another year doesn't matter for the NATS feature in that the NATS simply will not work, you would no longer need a chipped key. However, there are other wiring differences that require that you swap around pins in the connector. I don't know exactly which pins, but others have done it.

fastasleep

I will do that! Thank you for your input. I figured that I would have some re-pinning to do if I swapped to another ECU. This isn't a problem (I work on old Mitsubishi's, so I am used to it. LOL)
BTW, I did do a search and there was one other person that had the EXACT same problems as I am having, but there was no resolution. I will post whatever I find to be the true repair so that others may have a reference if they run into the same thing.
Thanks again! Any other ideas?

-Les

fastasleep

The car continues to run with the IGN 30A fuse pulled. Also, I noticed that if it is cold it will shut off, but once it gets a little warm it will not. I don't know if I can tell when it will NOT shut off by the car beginning to idle a little rough, but it did seem to happen at about the same time.

-Les

DennisMik

iTrader: (2)

One fuse/theory destroyed. One thing that I cannot be sure of is the specific relay you refer to as the EGI relay. Nissan unfortunately will use multiple names for a part. Is this the relay in the box in front of the battery that is front row left corner, next to the radiator? If so, this relay does 2 things. One set of contacts provides power to the ECU and another set provides power to the ignition coils, the red wire on each coil. The fuse I mentioned earlier has nothing to do with this relay.

Fuses # 57 supplies power to the ECU on pins 67 & 42. Fuse 58 supplies the power for the ignition coils. These 2 fuses are under the hood by the battery, labelled "ECCS" and "ECCS 2". If pulling either of these fuses causes the engine to stop, then I am in the correct area. What this would translate to is that one (or both) set(s) of contacts are sticking closed when the key is turned off. The "IGN SW" fuse I referenced earlier provides the power to energize this relay, so when you pulled the fuse, we know that the relay contacts should have opened up if the relay is good.

You can swap the relay with any other one as long as it is the same color.

As I mentioned above, this relay sends power to the ECU. There are also 2 other pins on the ECU that get power. Pin 24 gets power when the ignition switch is turned on and pin 80 has constant power from fuse 58 that also powers the ignition coils.

I know that you think that maybe changing the ECU will resolve the problem. I am not at the point of saying the ECU is the problem. I once tried to take the ECU out of my 97 and couldn't do it, but others have done it. So you want to make sure it is bad before swapping it.

I have a chart that lists/compares all of the ECU pins for all of the 4th gen Maxima years. The pins that are not the same in all the different years are highlighted in yellow. It is a PDF file that I can't post here. If you are interested, pm me your e-mail address and I will send it to you.

fastasleep

Thanks for your reply. Here is where I am: yes, the EGI relay that I am referring to is the tan 6-pin in the far left and bottom position when viewed from the front of the car. I can pull this and the engine cuts off. I did switch this with another that was near it and the same thing happened.
After I changed the oil this morning it seemed as if it was running very well and shutting off when the key was turned off even while warm. I put $20 worth of gasoline in it and drove it about 7 miles and it began to hesitate and stall. It began puffing white smoke again and drained the gas. I was just towed home.
I am not convinced it is the ECU; I took it out and looked at the board, paying close attention to the capacitors. None of the board was discolored or smelled bad and none of the caps were disfigured or leaking.
I came back and scanned it and it gave me a 0300, 1335, 0335, and an O2 code I can't remember right now. I think the crank sensor (REF) code was due to the extended cranking and the O2 code was due to the excessive fuel and the 0300 would have shown a random multiple miss due to the excessive fuel or bad crank sensor signal.
Man, this car is frustrating! lol.

-Les

vqmaxman

Go back and check the injectors make sure they are the right ones and they are installed on right, if not are they will do something to similar to what your describing. I would check all of the installations and vaccume lines, fuel lines, and fuel rails. I again am saying that you check the oil level and the color on the dipstick,becuase of the white smoke and the p0300 code that your getting it's sound like a blown head gasket issue. The color on the dipstick will also tell you the case.

fastasleep

I pulled all the plugs again and found another wet one. I replaced that injector as well (#4) and changed the oil again. It appears that the car is running well again, but I am getting another O2 code and I think I may need to change the catalytic converter.
I am still not sure that I do not have a harness issue, but the thing is running well and I will report any other issues. Thanks for the help!

-Les

JwaxMax99

iTrader: (14)

The raw fuel kills the O2 sensor. Had the same issue a with stuck injector. Replace the O2 and you are good to go.