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Phwoah2005

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Hi guys my first post on here but having an issue I can't sort and hoping someone can help.
My d22 zd30 suddenly started over boosting constantntly I have replaced the actuator and vacuum hoses.
The boost solenoid
And checked all the vacuum hoses I can see
And still having the issue.
I drove it carefully to closest mechanic who plugs his scan tool in and it did not have any fault codes but was reading 14psi at idle.
Does anyone have any ideas
Oh and I have done the egr/swirl valve mod if that helps
 

bods

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Hey mate. I'd you have replaced the map sensor and still having the same problem, the only other thing it could be is the wastegate stuck shut inside the turbo housing. Have you confirmed the boost pressure with an external gauge or just what the mechanic has told you? The zd30 navaras don't use the standard OBD2 system that the yd25s run, so unless he has the correct equipment to see what the ecu is seeing then he will have the wrong info. How do you know it is overboosting? Is it going into limp mode or some other issue?

This won't allow the turbo to produce 14psi at idle though as the navaras run a standard wastegate turbo, so the wastegate starts opening at whatever pressure the spring inside the actuator is set at, with pleasure being fed in from the compressor housing on the turbo. The only way to increase this is to fit a manual boost controller.

The patrols run a vnt turbo, which is controlled by the ecu increasing or reducing vacuum on the vanes inside the turbo. The D40 runs the same sort of setup as this, although I believe the later models went to an electronic actuator on the turbo itself.
 

Phwoah2005

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When I changed the actuator over the waste get was opening as closing freely.
The map sensor and boost are the same thing aren't they? If so I changed it but only with a second hand one
I will hook up a boost gauge tomorrow and confirm the psi
 

bods

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Yeah the Navara only runs the map sensor, from memory it bolts on the crossover pipe on top of the motor.

What's making you think it is overboosting now, are you getting power loss or something else?
 
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Phwoah2005

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Yeah doesn't seem to have power and I can hear it spool up as soon as I'm on the throttle where as before you wouldn't hear the whistle until 2500rpm
 

bods

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Have you got an intercooler fitted? I'd be having a good look over the joiners (have a good look even if you don't have an intercooler) to make sure none of them are leaking. I believe a common problem with them is breaking the EGR pipe too, so you may be hearing a boost leak. Anything leaking on the exhaust side will leave a black sooty mark, so have a good look around the exhaust manifold and EGR pipe to see if you have any leaks there too...
 

Phwoah2005

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ok so its not an overboost issue, its 10 psi at 3000 rpm. i ran my eye over hoses, manifold etc and cant see any loose hoses or anywhere it would be leaking boost. i had my partner give it a rev while i had my head under the bonnet but only noise i can hear is coming from the turbo and hard to distinguish if its normal turbo whine or boost leak
 

Horatius

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ok so its not an overboost issue, its 10 psi at 3000 rpm. i ran my eye over hoses, manifold etc and cant see any loose hoses or anywhere it would be leaking boost. i had my partner give it a rev while i had my head under the bonnet but only noise i can hear is coming from the turbo and hard to distinguish if its normal turbo whine or boost leak
It sounds like your map sensor is kaput (or hose to it blocked/split/kinked, or wiring /plug faulty). If that happens you'll struggle to get to 10psi boost and it will be quite gutless.

Disconnect the map sensor and take it for a run. If it makes no difference that's likely what the problem is.
 

Horatius

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ok so its not an overboost issue, its 10 psi at 3000 rpm.
In what gear? In 4th gear revving it out to 3000 rpm it should be 13-15 psi (at least mine is). If your map sensor is faulty it will struggle to get up to 10 psi and feel like it has no power at all.
 

Phwoah2005

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It sounds like your map sensor is kaput (or hose to it blocked/split/kinked, or wiring /plug faulty). If that happens you'll struggle to get to 10psi boost and it will be quite gutless.

Disconnect the map sensor and take it for a run. If it makes no difference that's likely what the problem is.
i did swap it out for a second hand map and i replace all hoses to it cause thats where i put the t joint for the boost gauge
 
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Phwoah2005

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a quick thought a couple people have mentioned the wastegate being stuck open or closed now i did swap the actuator out and with the rod coming out of the actuator disconnected it moves freely but with the rod connected i havent got a hope in hell of moving it. does this sound right/normal
 

tweak'e

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ok so its not an overboost issue, its 10 psi at 3000 rpm.
is that at speed in say 3rd or higher gear?
you won't get max boost while sitting in the driveway, you need to put some load on it.
first thing i would do is go unplug the gearbox neutral switch.
 

Phwoah2005

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is that at speed in say 3rd or higher gear?
you won't get max boost while sitting in the driveway, you need to put some load on it.
first thing i would do is go unplug the gearbox neutral switch.
yeah that reading is in the driveway. dont think the nps is playing up as the revs are dropping when going through the gears with it on
 

Horatius

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yeah that reading is in the driveway. dont think the nps is playing up as the revs are dropping when going through the gears with it on
What boost does it get in 3rd or higher at 3000 rpm? If it's getting 13-15 psi that would be about normal.

Sounds like you have ruled out the map sensor. As tweak'e says, it won't hurt to disconnect the nps to see what happens?
 

Phwoah2005

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its out of rego right now until i can get it fixed so dont really want to go driving it to find out
 

bods

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You're not really going to have a lot of choice. Maybe get a temporary movement permit for it? Check with your licensing authority about them, but you can't try and find out what the problem is unless you drive it or have it on a dyno...

Has something changed from previously, or have you only just bought it?
 
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Horatius

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Not sure you should be getting 10psi boost sitting in the driveway but anyway, you won't be able to diagnose it properly unless you can drive it. Equally how will you know if it's fixed unless you drive it? As it seems to be running at least, you might have to get it registered first?
 

tweak'e

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yeah that reading is in the driveway. dont think the nps is playing up as the revs are dropping when going through the gears with it on
that means nothing.
its a common cause of low power issues and its really easy to fix.
you can try the heat switch test method, engine idle should go up with heat switch on and gearbox in neutral. if it doesn't switch is faulty.
however they often go intermittent which is why unplugging the switch and driving it is the best test method.
 

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