1999 GXE MT, I've tried everything friends/mechanics and myself have come up with so far, not sure where else to turn. I have a 99 gxe AT sitting in the drive, company went under and never sent the title, already got our money back, but no one owns the car, so I can swap any compatible parts off of it if anyone has ideas.

9 days ago, we were doing some work on the car.
#1, we replaced the power steering reservoir and hose clamps
#2, we degreased the engine bay and pressure washed the engine bay.
#3, we replaced the .066 gapped plugs with iridiums at .044
#4, we started the engine, noticed a couple misfires but ignored.
#5, changed the oil, started the car and rolled it flat, then added a little more oil.
#6, replaced a cracked vacuum hose and unkinked a heater hose.
#7, washed the engine bay clean again due to a little power steering and oil spill.

Now, I know you are supposed to keep the engine running while washing the engine bay... for some reason this time, my mechanic friend didn't turn the car on first. I also was just told never to use a pressure nozel, which he also did. And as I noted before, after the first wash, I noticed a few misfires, but nothing major.

Now the bad part... after the second wash, the car wouldn't even start even after air drying the engine bay. We let it dry for a few hours, still wouldn't start. The next day we noticed there was still a lot of water on top of the engine over one of the sensors, so we sopped it up and air dried it again. Still wouldn't start. The third day, some of the mechanics at the shop I used to take it to told us it wouldn't start one time until they fiddled with the ground wires. So we messed with them, and it fired up. It was still misfiring randomly though. It would only drive about 2 miles at a time before misfiring so bad that it would die. Then it wouldn't start again until I fiddled with the ground wires. Disconnecting the battery ground DOES NOT WORK. I have to fiddle with the ground wires that are going to the top of the block, it's a hyper grounding kit or something. After fiddling with those wires, it starts again... Since then I have found, as long as I don't drive it, it wont die, despite the misfires. And as long as it doesn't die, I can always restart it.

CEL's that popped up were...
P0340, Bank 1 camshaft position sensor
P0325, Knock Sensor
P0420, Catalytic Effeciency (fastcat + bad gasket)
P0335, Crankshaft Position Sensor A circuit malfunction
P1336, Crankshaft Position Sensor

#1, found water in two spark plug ports, air dried, still no good.
#2, swapped in nearly brand new coilpacks off other maxima, still no good.
#3, replaced iridiums with basic copper plugs, still no good.
#4, replaced ground wires with 1/0 gauge wire w/ gold plated brass terminal ends. Still no good.
#5, pulled and cleaned all grounds and coated with dielectric grease, still no good.
#6, per a previous thread, dielectric greased and added 4 gauge transmission ground, still no good.
#7, swapped and cleaned the camshaft position sensor off other maxima, still no good.
#8, replaced shot harness on crankshaft pos sensor, still no good.
#8, swapped and cleaned crankshaft pos sensor from other maxima, still no good.

I'm personally out of ideas, pissed off, and getting rather irritable since nothing seems to be working. The car is still acting exactly the same as it was 9 days ago. It starts after a couple turns, then runs fine for 30+ seconds, then you'll hear a single misfire... then a few more... then it's just random from there... sometimes it runs good for a minute, then it's back to randomly misfiring. If I unplug one of the coilpacks, it seems to actually run smooth, but still sputters randomly when driven.

Does anyone else have any ideas?

 

Remove, disconnect, clean and dry every electrical connection under the hood.
You've got water somewhere it's not supposed to be.
The pressure washer is most likely the cause.

 

I've cleaned my engine bay once in the time I've owned my Max (simple green and then a very light MIST spray to rinse it off, then left it to sit for four hours before trying to start it), but I'd personally never be ballsy enough to pressure-wash under the hood of a 4th gen for fear of damaging something.

 

Well I took mine for a pressure wash at BP a few months ago and it fired right up after the wash. It threw a code for the Inhibitor Switch but I knew it would come because the harness is partially damaged and prone to water. After drying it out, no issues.

OP, those crankshaft codes I wouldn't be too worried about because that's from excessive cranking trying to get it to start. If the starter was turning over slow, those codes will appear.

For the driving and cutting off, I would check your air passage from the Air Filter going into the engine including MAF as water may be there also. If you let the car idle and reach full operating temp, the water will evaporate except the part where the fuel rails are located.

 

Previously it threw the P1336 Crank pos sensor code, when we just checked it had only thrown the cam pos sensor and P1335 crank pos sensor instead of the P1336. We cleared the codes again, and this time only the cam pos sensor came back, which I already changed out with one from another 99 maxima that was previously running good. I'll check the air passage, but it has been 9 days and the car has run multiple times for 30 minutes in the driveway, so I would assume any water in there has evaporated.

 

You know what they say when you assume?
2000 psi of water gets into places that aren't really open to air drying.
Your issue started after the wash.

 

Very True. OP did you remove your ignition coils to see if there is water in those tubes??

 

There was water in two of the ports, I sprayed 200psi air in them for a few minutes until water stopped spraying up. I also switched out all the ignition coils from another maxima which were in better condition then mine.

 

If the camsensor is the only code being thrown, then I would check the voltage coming through the harness and check for continuity.

 

Just checked the sensor to be sure... it's returning 2377 ohms which is between the 2050 and 2550 for a mitsubishi sensor according to the chilton manual. It's 76 degrees out rather then 68, though I doubt that makes a huge difference. I'm not sure what voltage should be coming through on the harness, let me see if I can figure that out.

 

Cam pos harness is only giving me a measly 1.8 mV and 10.8 mV when directly grounded to the main ground. Whereas the crank pos harness is giving me 12.26 v. Any ideas? We checked every fuse twice a few days ago, none were blown at the time.

 

If my memory serves me correctly, if it was a fuse, you would get codes for the O2 sensors as well. We will rule that out for now. Measure the resistance of the sensor and give me the make which should be Hitachi or Mitsubishi. Also, do a test and disconnect the harness and try to start the car and let me know if it starts or not without the sensor being connected.

 

The first time we checked codes, the code reader said O2 Sensor and O2 heater, but when I looked up the codes it gave, none of them came back as that.

The sensor itself shows 2377 ohms (edit, and is a Mitsubishi). The car will not start without it plugged in, and starts and misfires randomly when it is plugged in.

 

After this, for sure its a harness problem. The sensor is good and within spec. The manual says for you to check power, you must check for continuity between pin 1 to your left (with clip facing up) and ECU pin 46 and 47. Also, pin 2 from harness to engine ground should show continuity.

 

Hey man, I tested the ground and it definitely has conductivity. I also figured out where the ECU is, but I'm not really sure how to go about pulling it apart and testing the pins, is there a tut somewhere? I'll see if I can find some instructions or something.

Also noticed, it looks like my ECU has been modified or replaced. The warning label next to the self test dial is missing, and the self test dial itself is just a hole, no screw. Kind of strange.

 

Alright, got the ecu wiring harness off and tested continuity, according to the wiring diagram my friend gave me, pin 44 and 48 are the ones for the cam pos harness.. both give conductivity according to my meter.

 

Yes it is pins 44 and 48. Sorry about that as I was looking at the wrong year FSM. If you do have continuity, then I would inspect the harness plug going into the sensor. That could be the only thing I can think of. I will try and get a voltage reading coming through pin 1 and let you know if its far different from what you posted before.

 

Hopefully it wont be raining tomorrow, I want to test the ECU itself and see if the voltage reading is different then the harness is getting. Maybe the wire is broken and just a few strands remain, making it seem conductive, but not enough so to power the sensor. If you can get a good voltage reading on the harness, then I can tell if the ECU could be bad or if it's the wire, etc. If not, I have friends with a 2001 and a 2003 maxima I can test the voltage on, the other 99 maxima, we lost the key, so I can't test it.

 

I noticed when I was messing with the ecu, that it looks like it's been changed out or something... The dial for self testing isn't even on the ECU, and the warning label is missing.. the brackets are bent and scratched up...

So today, we pulled the ECU out... and the code on it is A18-N05-Z85, which is for a 1999 Nissan Maxima, Automatic, Fed, W/O TC..... My car is not an automatic... So now I'm wondering... Is this t he completely wrong ECU? or was it replaced once before and reprogrammed?

 

The different housing only means just that, its a different housing. Whats on the inside is obviously different

 

Ah, that makes sense.

I guess I was wrong though. My mechanic sent me A18-N07-Z87, and I looked it up, NOTHING, not a single document on google has that ECU code, so I assumed he accidentally hit the 7, and it was a 5... It is in fact a 7, I have the ECU in front of me now. I can't find anything on that ECU code at all. No used ones ever for sale on ebay, nothing on google, etc. I had the dealership look up the part number and he gave me three for my VIN. 2371C-4L880RE, 23713-4L663, 23713-4L664 which come up as Fed,MT,GXE which is right, but I'm not sure how to go ab out getting a used one instead of paying $900.

 

Bump....

I drove the car 5 miles from the shop to a friends house to work on some other stuff... It didn't die at all this time, which leads me to believe the water in two coilpacks is what was causing that. I kept it in higher RPM (3-3.5k) the entire way. It seems to shudder a lot off the line, up to 2500 rpm or so, once I hit 3000 RPM it drives pretty normal. I even punched it across an intersection and it chirped the tires all the way from 3k to 6k rpm like it still has all it's power. I have read previously that when coilpacks are going bad, it misfires at lower RPM's.... but I already changed the coilpacks. Any other ideas?