Navara V9X Starting and Power Issues

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Old.Tony

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I have a problem with concurrent codes like that, they're so often the result of a poor electrical connection. Not sure this is the case now, because of how many things you've already been over on the engine you've likely fixed these issues already by unplugging and replugging things.

The boost sensor error indicates a fault with the response from that sensor. It's not a common failure. It's worth taking it out, cleaning it and reinstalling it to see if that helps.

The exhaust pressure error - my understanding is that this error is because of a mismatch in pressure reading between the exhaust and the intake manifold before the engine is started. Pressures at this time should be identical (which means the return voltage from the sensors is supposed to be the same within a very small margin for error). I'd say either the sensor has failed, or isn't connecting properly. This connection could be the electrical connector to the sensor (which probably only has two wires, one for a positive steady voltage going in, and one to return the adjusted voltage to the ECU). This sensor gets its negative from being earthed on the exhaust. What if your exhaust isn't earthed properly? You can clean the sensor all you like, but until the exhaust is earthed properly you'll continue getting this problem.

Test it (test both like this): check the resistance between the intercooler body and the battery negative (NOT the body, go straight to the source). You should get a very, very low reading. Do the same for the exhaust, should get a very, very low reading. If it's above a couple of ohms, you have an earthing problem. Negative wire to the engine block, maybe? Try attaching another wire from the battery negative to the intercooler, take the truck out and give it some berries. Still get the error? The pressure sensor may need to be replaced.

NOTE: I say intercooler body because that's where the turbocharger boost pressure sensor on the YD25 D40 is. I am not sure where this sensor is on the V9X, but you're chasing the earth point there.
 

Supermike

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It's fixed! All problems now solved, well almost. Fault codes no gone and truck drives better than it ever did. Turns out the "new" solenoid valve for the turbo actuator was defective and was causing around 40psi of boost.... Hopefully I haven't damaged the turbo, but luckily the truck was cutting the boost off as soon as it was getting high and it runs good now. Do have a slight issue with the engine fan sometimes staying on, think the clutch might be sticking... Thank you to all for your suggestions and assistance. Greatly appreciated and hopefully this thread will help others in the future
 

Supermike

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Oh and to summarise the route cause of the problem... The intercooler leaking. Basically loosing boost pressure and causing the truck to run rich, this in turn clogged the DPF (which is at its design limit anyway) and also clogged the EGR (common failure on the V9X) doesn't help that most of my journeys are short so never triggered a DPF regen.
 

trimb

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Oh and to summarise the route cause of the problem... The intercooler leaking. Basically loosing boost pressure and causing the truck to run rich, this in turn clogged the DPF (which is at its design limit anyway) and also clogged the EGR (common failure on the V9X) doesn't help that most of my journeys are short so never triggered a DPF regen.
V9x and DPF? Regeneration? There is no DPF
 

Supermike

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Right you are, I was speaking for Aus delivered versions
I would much prefer the Aus derived version. Well all still going good, still have an issue with the fan stating engaged for an extended time after starting. Perhaps down to me blanking the EGR valve at the intake manifold side. Not sure if it's heating the EGR cooler which in turn is triggering a sensor?
 

Old.Tony

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If you've got a fan like we have here - with a viscous hub behind it - it won't have anything to do with the EGR. The viscous hub is easy to spot, looks like a circular heatsink that the radiator fan mounts to, and in the very centre of the front of the hub is what looks like a small spring (and it is). When this spring is heated to around 91 degrees celcius, the centre rotates which closes a valve inside the hub causing it to lock. This causes the fan to be driven quite hard by the engine at temperatures above 91C. Below this, the fan slips a fair bit.

Now this can be modified simply through adding or removing silicone oil from inside. Add more to lock the hub sooner (lower temperature), remove some oil to raise the temperature (this isn't the science, it's the effect). If you find your fan isn't cooling enough, it's probably slipping too much (see below for the test). If it's coming on too early, it might have too much oil (or be damaged in some other way).

Testing the fan: best done by two people and takes all of a minute. While you're driving somewhere (and after the engine has reached normal operating temperature), pull over and pop the bonnet. Watch the fan from the side and signal your assistant to turn off the engine. If the fan stops with the engine (no spinning afterwards) then it's either working normally or it's working too well (and that's not going to hurt). If the fan keeps running on after the engine has stopped, it needs more oil inside the hub.

Of course, you might have a different hub behind the fan - I can only speak to what I've played with or seen in the service manuels.
 
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The V9X engine cooling fan is free wheeling until an electrical signal from ECM couples the fan to the accessory drive belt system.
ECM calculates required fan speed needed for the current engine condition (derived from 9 sensor inputs to ECM) & outputs a pulsed coupling signal to the fan hub to achieve a requested fan speed.
 

Supermike

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The V9X engine cooling fan is free wheeling until an electrical signal from ECM couples the fan to the accessory drive belt system.
ECM calculates required fan speed needed for the current engine condition (derived from 9 sensor inputs to ECM) & outputs a pulsed coupling signal to the fan hub to achieve a requested fan speed.
You beat me to it - although in far greater detail than I knew! So it comes on as usual when first started in the morning and goes off, but then comes back on until truck is up to temp then goes off and generally doesn't come back on again even when restarted unless I have left if over night.
 
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Not sure if this will help or confuse.

V9X COOLING FAN CONTROL

Ok, Inputs from external sensors to ECM.

Camshaft position sensor (along with crankshaft info (next), ECU calculates engine RPM).
Crankshaft position sensor (ECU engine RPM calculation, see above).
Engine coolant temperature sensor.
Refrigerant pressure sensor (Aircon cycled on or off).
Intake air temperature sensor (part of MAF sensor).
Battery voltage (along with engine speed, ECM determines engine is running).
ABS actuator electric unit (vehicle speed).
BCM (Body Control Module) Tells ECM if A/Con & cabin blower fan are requested on.
Fan speed sensor (on fan hub, feedback to ECM re requested fan speed).

SYSTEM DESCRIPTION
Based on a signal transmitted from each sensor, ECM will calculate a target fan speed responsive to a driving condition.
In addition, ECM calculates a fan pulley speed according to an engine speed and transmits a cooling fan speed request signal to IPDM (Integrated Power Distribution Module) via the CAN communication line to satisfy the target fan speed.
Then, IPDM transmits ON/OFF pulse duty signal to fan electric control coupling.
The cooling fan speed sensor detects cooling fan speed and transmits the result to ECM for requested/actual speed (feed back, i've asked & i've got).

!!!!!!!!!!!!!!!!!!!!

Benno
 

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