[GUHeaven]

I’ve got a 2007 GU Patrol ZD30 CRD with 210,000KM. It has a 2010 engine as the original blew up and was replaced by Nissan at approx 60,000KM. So the engine has 150,000KM on it. It has had the oil sensor faulting for over 12 months but never been low on oil and that part of the loom is caked in oil. It has a fairly bad oil leak on the block that needs to be investigated.



Someone else was driving it and phoned me up when they were struggling to do 60KM/h climbing the Westgate Bridge. They then managed to get it to Brooklyn. It had oil level just below the low mark. I had checked the oil 5 days before and it was in between low and high. I have been pretty regular checking the oil because of the oil pressure warning light and also the leaks.



When I got there, it wouldn’t idle for long and it was spewing smoke out. When it did run it was really rough firing and unable to move. Seemed to be a cylinder down. Got an OBD error about injector 4 and that connector was heavily covered in oil. Cleaned that up and it made no difference. So had to tow it home.



As you will read below, things really improve when the MAP Sensor is removed. I also use ECM to mean ECU as the Nissan literature refers to this as the ECM. As you can see this has been going on for a week now. Glad I haven’t been paying workshop rates. Does anyone out there have any great ideas?



Also if anyone out there has a GU CRD, what voltages do you get a on Pin 1 and Pin 2 of the Crankshaft sensor? Approx 5V and 0V like the manual says or 2.5V like I see?



Fault Codes:



Oil Pressure Sensor: Been active for 12 months. This is the only code that cannot be cleared because of suspected loom damage.

Turbo Boost (MAP) Sensor: Illuminates MIL when sensor is disconnected from the wiring harness. This is an expected error.

EGR Valve: Seen when the MAP is disconnected. This is an expected error.

Injector Number 4: Appeared when first hooked into OBD2 after vehicle wouldn’t start. Cleaned connector which was heavily caked in oil and have not seen it again.

Crank Sensor: Seen when the Crankshaft Sensor is disconnected from the wiring harness. This is an expected error.



Tested items:



Turbo Boost (MAP) Sensor: Tested on the bench and behaves just like the graph in the service manual. Voltages are fine. Also replaced MAP with one from another ZD30 that didn’t have issues and this did not improve things. ECM can see when the MAF is not present and it also returns pressure readings via the ECM of 100kpa which is approximately atmospheric pressure when idling. With the MAP connected the engine stalls shortly after starting and blows lots of white smoke and idles roughly. If you disconnect the MAP you get an error code and a MIL but the engine will keep running and happily rev to 4000 RPM. The engine will run without the MAP under and drive on a flat surface. However it will stall when trying to drive up a small ramp. With the MAP connected it almost sounds / feels like it is a cylinder down. Without the MAP connected it behaves like it did before the problems started.



MAF Sensor: Tested on the bench and operating on the vehicle and flow and temperature sensors behaved as per the service manual. Also replaced MAF with one from another ZD30 that didn’t have issues and this did not improve things.



Crankshaft Sensor: (See Service Manual EC-218 to EC-222) Pin 1 is 2.5V and the service manual says this should be approximately 5V (with reference to the vehicle ground) with the ignition on using a digital multimeter. Placed Pin 1 on a CRO with ignition on but motor not running and see approx 2V and a DC signal with no AC components < 20MHz. Pin 2 which is the sensor ground is also 2.5V with reference to the vehicle ground when the ignition is on. Pin 2 is supposed to be approximately 0V. However the sensor output on Pin 1 looks on the CRO looks exactly like the waveform on the service manual. As revs increase so does the amplitude and frequency. We also see the funny knee shape that is in the service manual. Although the DC voltages are weird, the AC signal that the ECM reads looks perfect. When this sensor is disconnected, the vehicle fails to start and will throw a crank shaft sensor error code. Also tested each of the 3 sensor wires from engine bay to ECM plug for continuity, shorts to ground and also shorts / high impedance paths to each other. All harness checks passed.



Fuel Pressure: OBD2 reports that common rail pressure is between 30 and 40 Mpa at idle and up to 100Mpa at higher revs and this matches what the service manual says about fuel rail pressure. Fuel pressure sensor could be faulty but the ECM seems to be getting plausible values.



Cylinder Compression: Hooked a pressure gauge up through the glow plugs and lowest cylinder was 390PSI and highest was just over 400PSI. The manual says this should be about 420PSI from new. Common wisdom is that compression above 300PSI is okay for engines that have been driven for over 100k KM.



Battery: I have two batteries wired in parallel with 0GA cable. They are about 4 years old but the last pair lasted 8+ years. I have ensured that they have been fully charged at various points in the testing regime using a high current power supply. Don’t see the 12V rail dip too low during starting.



Turbo, turbo piping and solenoid: During fault finding I have taken the intercooler out and left the engine naturally aspirated. Even if there was over boost, stuck valve etc the boost would never make it into the block.



Blocked air cleaner / piping: Not a problem as I only have a short pipe feeding air into the block. Effectively bypassing all of the air intake.



Accelerator: Have not tested this as per the service manual. However without the MAP connected you can use the pedal and go from idle to 4000 RPM nice and smoothly like yo would expect.



Idling speed: Using the OBD2 reading with the MAF sensor removed this is very close to 750RPM and 1200RPM (in heat up mode). This matches what I would expect from reading the service manual.



Exhaust Gas Control Circuit: Have not looked at this as the entire EGR system is bypassed during most of the testing.



Start Signal: Have not tested this as the start signal appears to be working as I can start the vehicle with the MAP removed.



Swirl Control Valve: Have not tested this.



Glow Control System: Have not tested this and the glow plugs power is currently disconnected. However it is summer at the moment and I drove around for nearly 10 years with a blow fusible link for the glow plugs. Engine starts okay with the MAP sensor removed.



Fuel Pressure relief valve: I have not tested this as the fuel rail appears to be providing good fuel pressure via OBD2. That sensor seems to be giving plausible readings. Might quickly check if fuel is passing through the pressure relief valve.



Cam Position Sensor: I have not tested this. Might quickly check this. However engine starts okay with the MAP sensor removed.



ECM: I have not tested this as per the service manual. Most functions appear to work, but it is not unheard of for a small section of the ECM to fail. There are 5 procedures for testing the ECM listed in the service manual.



Fuel Pump: Fuel pump appears to be working. Can see atomised diesel coming out of the exhaust and also air intake. Engine will run and rev to 4000 RPM with MAP removed. Fuel pressures seen via OBD from 30 – 100 Mpa. Interestingly I have not found a procedure for testing the fuel pump.



Consult: I’m also keen to start talking to the ECM using Nissan Consult. I’m hoping something in there can show me something that is not working. This also appears to be the way to test another ECM in the vehicle.

 

[AndrieK]

Seems like you have most bases covered… Only a few comments/questions I can think of:

1. If you are getting dodgy readings from the CKP sensor, have you tried a new / known good sensor the see if it makes a difference?

2. I wouldn’t be surprised if the engine is behaving weirdly the way you are running it. If I understand correctly you have no boost going into the engine but you MAF still reads the amount of air the turbo is “sucking” through the intake…? The ECM would expect a certain boost number for a corresponding MAF reading and TPS. By bypassing the IC and leaving the MAP to read 1atm, your fuelling will be all over the place. Clean the IC to make sure there’s no excessive oil in it and put it back in. Your MAP issue could be due to the sensor being fouled with oil.

3. Might be worthwhile stripping the engine harness out of the vehicle and giving all the connectors a good clean / inspection. Also clean the engine and sort out the oil leaks. You might be chasing your tail for a very long time if a dirty sensor / connector is the cause.

4. Look into the oil pressure sensor issue. Low oil level is not the only thing that can cause low oil pressure. Although saying that, if you had an oil system issue you probably would’ve had much bigger issues by now. Personally I would NEVER drive with an oil light on, no matter how confident I am that it’s a sensor issue.

Where are you located?

 

[AndrieK]

Also, if you plan on sticking around for a while, might be worthwhile popping into the New Members section and introduce yourself.

 

[GUHeaven]

AndrieK Thanks for the quick response.

1. If you are getting dodgy readings from the CKP sensor, have you tried a new / known good sensor the see if it makes a difference?

The dodgey voltages are coming from the ECM. So CKP sensor is disconnected and weird voltages from ECM when the ignition is on and motor is not running. When the engine is running voltages look like the manual. So if there is an issue it is the ECM not the CKP. Loom fully checked here.

2. I wouldn’t be surprised if the engine is behaving weirdly the way you are running it. If I understand correctly you have no boost going into the engine but you MAF still reads the amount of air the turbo is “sucking” through the intake…? The ECM would expect a certain boost number for a corresponding MAF reading and TPS. By bypassing the IC and leaving the MAP to read 1atm, your fuelling will be all over the place. Clean the IC to make sure there’s no excessive oil in it and put it back in. Your MAP issue could be due to the sensor being fouled with oil.

Agree. I have also run with all of the tubing in place and MAF reporting things correctly and MAP disconnected. Doesn't change things. But point taken,

3. Might be worthwhile stripping the engine harness out of the vehicle and giving all the connectors a good clean / inspection. Also clean the engine and sort out the oil leaks. You might be chasing your tail for a very long time if a dirty sensor / connector is the cause.

Yes that could be a fun little exercise. Should have a look at what the manual says about getting it out. That said every bit of the loom I have buzzed out looks good. Only issue was injector 4.

Where are you located?

Inner Melbourne.

Looks like I'm gonna get back into it.

 

[GUHeaven]

@AndrieK I also cleaned the MAP and MAF with some Valvoline MAF cleaner and also attacked the connectors for these sensors and the injectors with Deoxit F5 (Deoxit Fader F5 Spray 142g - Altronics) which is a cleaner / lube for faders and pots. It plays nicely with plastic connectors and works a dream in my audio pursuits. Assuming that the service manual has the correct operating parameters for the MAP and MAF I'm confident these work. Of course I could be wrong there. Plus I tried some donors from another vehicle.

 

[GUHeaven]

@AndrieK after heading your advice on the Oil Pressure, and having some spare time while I think more about this vehicle, I decided to investigate the oil pressure sensor to distract myself. It is hard to get to the sensor itself but I disconnected the connector in the engine bay and was able to tap the loom from there. Following the service manual I got 5V and GND on those pins with the ignition on from the ECM (big tick). I then used a needle to tap the sense wire with the loom back in and ignition on. The clever engineers from Nissan Japan assert this should be about 1.3V and I'm getting 5V. I'm getting a high voltage fault code and this would be why. So it seems like the sensor has gone. So it thinks it has high oil pressure when there is none. I also got a huge number of new fault codes from having ignition on with the loom disconnected in the engine bay. One was about there not being continuity to the oil pressure sensor. So I have the right connector.

With my next steps, I think that given I have over 200,000KM on the injectors I might spend some money getting them flow tested and ruled out. They seem okay but it is possible they are over fueling and my removal of the MAP forces the ECM them to lower their duty cycle and reduce the fuelling. The other theory is the barometric sensor in the ECM is faulty, but aside Consult II I have not been able to find a way to read that. I looked into trying to get into the ECM but that looks like a lot of mucking around for a long shot.

 

[GUHeaven]

Looks like my major issue was that the EGR volume valve is missing the butterfly / vane. Which I suspect being open all the time resulted in the engine running lean with all of those EGRs flowing. Trying to find that vane but haven't found it in the intake manifold with my new inspection camera.

 

[AndrieK]

Looks like my major issue was that the EGR volume valve is missing the butterfly / vane. Which I suspect being open all the time resulted in the engine running lean with all of those EGRs flowing. Trying to find that vane but haven't found it in the intake manifold with my new inspection camera.

So I take it your EGR isn’t blocked…?
If not, I’d do it now while you’re in there. Eliminate EGR issues once and for all.

 

[Nikolay]

Remove completely EGR, muffle the antifreeze outlet from the block and exhaust gases from the manifold