Help With Several Check Engine Codes - WEIRD!

[88suburbandriver]

Hello all, I just bought a 97 Maxima, 128k miles, 3.0L V6. It is currently running on 4 of the 6 cylinders. I did some diagnostics on the injectors and ignition coils, and neither was working on cylinders 2 and 4. I got voltage from the ECU to the injectors and coils, and the ohms were within acceptable range, etc. Here are the engine codes I am getting :

0307: Unable to obtain closed loop operation (right bank)
0308: Unable to obtain closed loop operation (left bank)
0201: Ignition signal primary circuit fault
0407: Crankshaft Postion Sensor (REF) or cirsuit fault

I decided to start with the crank pos. sensor. I replaced it and it still runs on 4 cylinders, however when I unplug that sensor, the car starts and runs on all 6 cylinders but not great (like timing is off).
I was under the assumption that the car wouldnt even start without that sensor......but Im obviously wrong. As far as the other codes, im not sure where to start with those.

Could this be an issue with the infamous wiring harness problems in this car? Am I a candidate for the transmission removal and regrounding of that ground cable? Any help would be greatly appreciated. Thanks

[Nahkapohjola]

Originally Posted by 88suburbandriver

...and regrounding of that ground cable?

Get new NGK plugs. If there is now bosch in, thats the problem.

Try swapping coilpacks. If problem moves, theres it...

Then harness ... if none above, its fried ECU ... contains coilpack drivers.

Transmission? No such gnd thing ... smbdy is now after u wallet $$$$.$$ - stay clear.

Cleanup, start from checking charge voltage ... see http://www.cardomain.com/ride/748507/14

[88suburbandriver]

Originally Posted by Nahkapohjola

Get new NGK plugs. If there is now bosch in, thats the problem.

Try swapping coilpacks. If problem moves, theres it...

Then harness ... if none above, its fried ECU ... contains coilpack drivers.

Transmission? No such gnd thing ... smbdy is now after u wallet $$$$.$$ - stay clear.

Cleanup, start from checking charge voltage ... see http://www.cardomain.com/ride/748507/14

I have swapped coil packs and injectors and the problem does not move, it stays with the cylinders, and they still do not fire. All injectors and coil packs are ok. I have tried a new ECU and the problem still exists, with the exact same codes. I am thinking its the harness, however Im not sure if I am up for replacing that. I will try to bypass any fried circuits that i find first. Should I start with the Crank sensor first, since its that thats giving me these wierd symptoms?

Any idea why all 6 cylinders fire when that crank sensor is unplugged? I plug it back in (with the new OEM sensor) and it starts firing on 4 clinders again. Was i supposed to reset the ECU after the sensor swap and before I fire it up again? I dont think that it matter. Thanks guys

[88suburbandriver]

UPDATE:

All signs point to the Crank Position Sensor (REF). I have tested the circuit from the sensor plug to the ECU, and as far as i can tell there is no short, etc. I hooked it up to the ODB computer and ran it down the road (on 4 cylinders). The O2 sensors did not function at all (no flucuation in voltage to ECU), and I received all 4 of the engine codes listed above. I then unhooked the REF Crank sensor, and the O2 sensors worked fine, and the car runs better. To test my theory I made a jumper wire and connected it across the 2 pins of the crank sensor (REF), and the car ran the same! How is this possible? What is on the crankshaft that sends the signal to the magnet in that sensor?

I have replaced the crank position sensor, tested the circuit to the ECU, and yet it still throughs an engine code.

I am out of ideas, except for trying yet another ECU.

Any ideas would extremely greatly appreciated.

[Nahkapohjola]

Same cylinders missing always? Which ones?

Listen to injectors click: screwdriver on, ear on handle. All have same click? (Read also FSM how that injector checkup is done)

Charge voltage at ECU, is it 13.5V or more?

When ECU is w/o pwr for 30 minutes, all is cleared = reset.

[88suburbandriver]

Originally Posted by Nahkapohjola

Same cylinders missing always? Which ones?

Listen to injectors click: screwdriver on, ear on handle. All have same click? (Read also FSM how that injector checkup is done)

Charge voltage at ECU, is it 13.5V or more?

When ECU is w/o pwr for 30 minutes, all is cleared = reset.

Same cylinders (#2 & #4) always missing - only when the REF crank sensor is plugged in.

Injectors work fine when REF crank switch is unplugged (why would I test those again?)


Im not sure where you are going with this????? I already said in a previous post that the car runs on all 6 cylinders when the sensor is unplugged, so logic would state that there is a problem with either the sensor, the harness plug, or the wiring harness itself, however I checked all of these items physically, so I think now that maybe the wiring is wrong at the ECU plug (which I have no idea how that could happen).

I bought the car in this condition, and the previous owner replaced almost every sensor on the car, as well as the ECU, but I dont know if he used the right ECU since there are so many that will physically plug in to this car.

Someone suggested that I reverse the wires at the wire harness that plugs into the crank pos. sensor. Would anyone recommend that or?????

[Nahkapohjola]

Originally Posted by 88suburbandriver

Same cylinders (#2 & #4) always missing - only when the REF crank sensor is plugged in.

Injectors work fine when REF crank switch is unplugged (why would I test those again?)


Im not sure where you are going with this????? I already said in a previous post that the car runs on all 6 cylinders when the sensor is unplugged, so logic would state that there is a problem with either the sensor, the harness plug, or the wiring harness itself, however I checked all of these items physically, so I think now that maybe the wiring is wrong at the ECU plug (which I have no idea how that could happen).

I bought the car in this condition, and the previous owner replaced almost every sensor on the car, as well as the ECU, but I dont know if he used the right ECU since there are so many that will physically plug in to this car.

Someone suggested that I reverse the wires at the wire harness that plugs into the crank pos. sensor. Would anyone recommend that or?????

Seems unbelievable equation. Like swapping spare tire would cause one cyl misfire...

ECU drives all injectors and coilpacks, It cannot select one or two not to function when pos or any other signal fails. Funny & loose or broken wiring: You must check all the wirings and wire color codes against FSM schema.

[DANGORDON666]

Hey I Had A Problem Similar To This And It Turned Out That The Original Owner Had Changed Plugs And Swapped Two Coil Wires.
The Funny Part Was They Looked Like They Should Have Been That Way.

[88suburbandriver]

Originally Posted by Nahkapohjola

You must check all the wirings and wire color codes against FSM schema.

Excuse me for being a noob, but what is a FSM schema?? I tried to Google it, and got 0 results. Thanks in advance

[Nahkapohjola]

Originally Posted by 88suburbandriver

Excuse me for being a noob, but what is a FSM schema?? I tried to Google it, and got 0 results. Thanks in advance

After reading all linky pages below, You can tell everyone asking that q...