Patrol 4x4 - Nissan Patrol Forum banner

1 - 17 of 17 Posts

·
Registered
Joined
·
518 Posts
Discussion Starter #1
Hi

Haven't posted in a while buy have a quick Q, re over-boosting.

2003 DX, ZD30.

EGR blocked at 40,000, turbo wound back a little to keep boost within rec range, catch can fitted. Filters, fluids maintained, egr temp and boost gauges fitted, temp range unchanged forom normal/ history, 3 inch exhaust fitted.

Now 165,000 and suddenly started chronic over boosting, can get to 25 psi in any gear at any time.

I'll clean the MAF this weekend, but any other ideas? What would happen if the EGR blocking plate had burnt through? Could it?

Thanks
 

·
Administrator
Y2KGUII ZD Wgn
Joined
·
48,215 Posts
You don't mention any boost control, so I can only assume you are still running on the vacuum solenoid controlled by the ECU, these were always potentially problematic, hence their usual bypass by other means.

If this is incorrect we can start again.
 

·
Registered
Joined
·
518 Posts
Discussion Starter #3
You don't mention any boost control, so I can only assume you are still running on the vacuum solenoid controlled by the ECU, these were always potentially problematic, hence their usual bypass by other means.

If this is incorrect we can start again.
Yeah no Dawes or any other boost control. Just out of the blue starting pushing up to 25 psi in any gear with at best 3/4 right boot. used to not really go past 15 ish unless I tried to over boost by easing up from around 100-110. Temps always been good not really over 450 (sensor post turbo) unless pushing hard up hill.
 

·
Administrator
Y2KGUII ZD Wgn
Joined
·
48,215 Posts
Yeah no Dawes or any other boost control. Just out of the blue starting pushing up to 25 psi in any gear with at best 3/4 right boot. used to not really go past 15 ish unless I tried to over boost by easing up from around 100-110. Temps always been good not really over 450 (sensor post turbo) unless pushing hard up hill.
The higher the boost the better the EGT (to a point) so you will not see any increase in EGT through higher boost. It really does sound like you have a problem with the vacuum solenoid, if you were losing vacuum through a split/damaged line etc you would be seeing lower boost as a result.

The solenoid internally takes filtered air from the resonator to blend it with vacuum to control boost. Maybe you can remove the solenoid and give it a clean and check for blockages. You could also check the VNT arm operates through its range smoothly.

Are you sure the boost gauge is OK, do you have a method of checking the accuracy of the gauge?
 

·
Registered
Joined
·
518 Posts
Discussion Starter #5
Ta, can you point me toward the solenoid?

Re the boost gauge, I do have faith in it as she goes into limp mode every drive if I don't back-off, makes it a bugger to keep up with the traffic form the lights.

What would happen if the egr was to remain open/ closed all the time, (i.e. not functioning properly)?
 

·
Administrator
Y2KGUII ZD Wgn
Joined
·
48,215 Posts
Ta, can you point me toward the solenoid?

Re the boost gauge, I do have faith in it as she goes into limp mode every drive if I don't back-off, makes it a bugger to keep up with the traffic form the lights.

What would happen if the egr was to remain open/ closed all the time, (i.e. not functioning properly)?
If you have the EGR blocked it really doesn't matter whether the valve itself is open or closed.

This is the solenoid.


Solenoid.jpg
 

·
Registered
Joined
·
518 Posts
Discussion Starter #7
meh, new boost solenoid, new MAF. Still over boosting with ease in every gear, 2000 rpm in second easily hits 25 psi. Can't climb hills, overtake or move of from the lights without going into limp. what next?
 

·
Registered
nissan patrol gu6
Joined
·
1,601 Posts
Does the turbo actuator arm move freely or is it jammed GU2 asked but i see no answer.

Sent from my SM-G925I using Tapatalk
 

·
Rogue
nissan gu patrol
Joined
·
20,220 Posts
Whats wrong with a DI boosting to 25psi peak in any gear when accelerating? What pressure is the boost settling to when cruising? Accelerating with 3/4 foot down, I'd always see over 18-20psi

Did you ever adjust the VNT actuator?
 

·
Registered
Joined
·
518 Posts
Discussion Starter #11
only adjustment was to wind back a bit ages ago when I first blocked the egr. never had any problem up until recently, when started massive over boost nearly all the time. Limp mode non stop any speed, any gear. Hold almost any half decent level of acceleration in any gear and into limp she goes.
 

·
Rogue
nissan gu patrol
Joined
·
20,220 Posts
Only other thing I could think of is your MAP is dirty or stuffed. If it's not seeing the boost it needs it might be pulling more, but I'm not confident that the MAP contributes to limp with the DIs unless it causes the MAFv to exceed limits.
 

·
Registered
Joined
·
518 Posts
Discussion Starter #13
I did clean it and from what I understand (not much) the MAF has little to do with boost pressure. I'll check the actuator this arvo and hopefully its stuck. should I be able to move it through movement range by hand?
 

·
Registered
nissan patrol gu6
Joined
·
1,601 Posts
I did clean it and from what I understand (not much) the MAF has little to do with boost pressure. I'll check the actuator this arvo and hopefully its stuck. should I be able to move it through movement range by hand?
Not by hand.
You should be able to move it buy sucking on the hose that runs to the actuator.

Sent from my SM-G925I using Tapatalk
 

·
Rogue
nissan gu patrol
Joined
·
20,220 Posts
I did clean it and from what I understand (not much) the MAF has little to do with boost pressure. I'll check the actuator this arvo and hopefully its stuck. should I be able to move it through movement range by hand?
Not the MAF, the MAP (Manifold Absolute Pressure) sensor. It's the little black box with two bolts on the front of the intercooler.
 

·
Premium Member
nissan patrol
Joined
·
3,946 Posts
Cleaning the MAP will do nothing. It has a membrane diaphragm inside.
If that is blocked or punctured it will not read.

You need to get a multi meter out and test its voltage.
Should be about 2.2v at idle, 3+ when giving it a rev.

If you have the hoses routed the wrong way on the solenoid it will not function and cause the boost to skyrocket.

Why not just knick it all off and fit a needle and vnt control valve?
 
1 - 17 of 17 Posts
Top