Hi everyone , need some advise please , I have a pathfinder 2006 r51 which is having an issue with intermittent boost , I have replaced the boost control solenoid , checked the turbo pressure sensor and traced all the pipes . I have found 2 electric solenoids on the os of the engine block but I can’t find any numbers for them and I know one will be for the turbo but I don’t know what the other is for , thanks in advance
Intermittent boost fault
- Thread starter Djlee
- Start date
Help Support Nissan Navara Forum:
The 2006 R51 will have the same engine as the Navara, which uses a vacuum controlled boost actuator. I'd check that those hoses (3mm rubber vac hose, available from Supercheap Auto and you'll need about 3 metres of it) are not only intact on the outside, but also check that you can't turn the hose easily on each connection (indicates a hardening of the rubber which will easily allow a leak).
Next to check is the turbo itself, and not just the impeller. Look around the exhaust manifold for any sooty emissions from cracks or holes (there shouldn't be any at all). Remove the intake from the turbocharger and wiggle the shaft, play should be non-existent.
Thats not the end of the list, just the more common issues. A failure in the EGR valve may also cause it to seem like it has a sudden lack of power, blocking the EGR is cheap and fairly quick (although doing so is illegal in most countries that require it as an emission control device, it's just really hard to tell if it IS blocked).
Next to check is the turbo itself, and not just the impeller. Look around the exhaust manifold for any sooty emissions from cracks or holes (there shouldn't be any at all). Remove the intake from the turbocharger and wiggle the shaft, play should be non-existent.
Thats not the end of the list, just the more common issues. A failure in the EGR valve may also cause it to seem like it has a sudden lack of power, blocking the EGR is cheap and fairly quick (although doing so is illegal in most countries that require it as an emission control device, it's just really hard to tell if it IS blocked).
Cobez
Member
What exactly is the issue in detail?
I had some boost issues with my 2006 D40 STX. If you are driving and you find it's boosting then it cuts out suddenly, that will be your ECU sensing overboost and cutting the fuel(this happens at 21psi)
If this is the case, i'd be getting a boost gauge fitted to make sure you aren't overboosting too much which can be problematic long term.
If it's not getting enough boost (feels laggy and slow like it's struggling bigtime) as Tony said, first point of call is always the vacuum lines. Check every line from that boost solenoid you replaced. Two of them will cross over the top of the engine manifold to the suction control valve on the battery side of the block. Check for tiny splits (even the smallest crack will cause an issue).
The other problem may be the SCV (suction control valve) itself. Symptoms are generally the same as when you have a split line or similar (laggy, slow, lack of power).
Absolute worst case, your turbo seals might be shot. You will know this though if you get under the car and look around the turbo area you will see oil around the turbo. That's generally not the case though, 8/10 it's to do with vacuum / boost solenoid / SCV.
Also try disconnecting your battery for an hour or so, then reconnect as this will do a hard reset on your ECU, sometimes they go into limp mode for whatever reason. Reset will usually clear that code that has caused the limp mode.
I had some boost issues with my 2006 D40 STX. If you are driving and you find it's boosting then it cuts out suddenly, that will be your ECU sensing overboost and cutting the fuel(this happens at 21psi)
If this is the case, i'd be getting a boost gauge fitted to make sure you aren't overboosting too much which can be problematic long term.
If it's not getting enough boost (feels laggy and slow like it's struggling bigtime) as Tony said, first point of call is always the vacuum lines. Check every line from that boost solenoid you replaced. Two of them will cross over the top of the engine manifold to the suction control valve on the battery side of the block. Check for tiny splits (even the smallest crack will cause an issue).
The other problem may be the SCV (suction control valve) itself. Symptoms are generally the same as when you have a split line or similar (laggy, slow, lack of power).
Absolute worst case, your turbo seals might be shot. You will know this though if you get under the car and look around the turbo area you will see oil around the turbo. That's generally not the case though, 8/10 it's to do with vacuum / boost solenoid / SCV.
Also try disconnecting your battery for an hour or so, then reconnect as this will do a hard reset on your ECU, sometimes they go into limp mode for whatever reason. Reset will usually clear that code that has caused the limp mode.
Thank you for the replies , I have changed the valve below the air box , the pipes across the engine and from the valve to the turbo etc have been changed , egr valve has been blocked off . It’s more like a pulsing of the turbo kinda fault , cheers
Last edited:
Cobez
Member
When it sits at idle, does the actuator arm on the turbo move up and down slowly?
Engine idling, bonnet up, assistant in the driver's seat, you watching the actuator ... if they lightly tap the accelerator to produce about 2,000rpm - does the arm move then? You could have one of the following if it doesn't move:
* Leaking vac hoses (most common). Get 3 metres of 3mm vac hose and replace it all.
* Faulty BCS (somewhat common). Can be replaced (about $240) and this allows the ECU to control boost but is prone to failure again. After mine failed twice I replaced it with a Tillix valve (www.tillix.com.au).
* Faulty actuator (rare). It is just a rubber diaphragm inside but the diaphragm is not individually replaceable. You might get another actuator off a wrecked car rather than a whole new turbo. Test yours by getting a new piece of 3mm hose, attach it to the top, and suck on the other end of the hose. You should be able to make the arm move - if not, the actuator is probably damaged but check the next point too.
* Stuck vanes inside the turbo (really rare). You should be able to move the shaft beneath the actuator up and down yourself (with engine off). If they refuse to move at all, the vanes may have siezed and you might want to look at another turbo. There's a Brisbane company that sells genuine Honeywell Garrett 2056V turbos for around $1500 including postage (price might have risen a little since we got ours). Nissan want over $3K for one, if memory is correct.
* Leaking vac hoses (most common). Get 3 metres of 3mm vac hose and replace it all.
* Faulty BCS (somewhat common). Can be replaced (about $240) and this allows the ECU to control boost but is prone to failure again. After mine failed twice I replaced it with a Tillix valve (www.tillix.com.au).
* Faulty actuator (rare). It is just a rubber diaphragm inside but the diaphragm is not individually replaceable. You might get another actuator off a wrecked car rather than a whole new turbo. Test yours by getting a new piece of 3mm hose, attach it to the top, and suck on the other end of the hose. You should be able to make the arm move - if not, the actuator is probably damaged but check the next point too.
* Stuck vanes inside the turbo (really rare). You should be able to move the shaft beneath the actuator up and down yourself (with engine off). If they refuse to move at all, the vanes may have siezed and you might want to look at another turbo. There's a Brisbane company that sells genuine Honeywell Garrett 2056V turbos for around $1500 including postage (price might have risen a little since we got ours). Nissan want over $3K for one, if memory is correct.
