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GUII ZD30DI Wgn
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Hi Ross,
Very sorry to hear that. I hope you will recover soon. There is no hurry.
Looking forward to hear from you.
Thanks mate. Something I had noticed and mentioned to a fellow DI owner with this turbo, with heat switch on and engine running at 1200rpm the boost gauge shows 2psi, have asked him to check his numbers.
 

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NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
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If the vanes are very closed when Idle (too much closed in fact), it is possible that boost builds up even at such low revs. In my case, below is what I get
  • when switching the heat 'ON', and
  • when pressing the pedal up to different Revs when stopped.
514042


At 2000RPM (second peak) I get 250mbar roughly, and you can see that the vanes are already slightly open.

514043


The arrangement with one Needle only and one Dawes maintain the vanes closed at their maximum authorized by the unique Needle until Boost builds up enough to open the Dawes. No actuator dancing before then, and back-pressure building-up. This is the reason I made my Dawes to open much earlier, and placed a second Needle behind the Dawes to regulate the flow, and get a 'gentle' & continuous opening of the vanes, killing that back-pressure and maximizing the flow of air instead.
Pressure is not flow, and what our motor needs is qty of air more than high pressures.

I do the same with my electronics, and see up to 4.5V MAF at 3000RPM (which I cap at 3.95V), with only +1.2bar max of boost, which is the limit I have set.

Now that I understand the VNT of this 3.0 Di Patrol much better , and read an article showing that the best efficiency of the VNT turbo is when the vanes are half-open (or half closed), I believe I have reached the best I can do to maximize the quantity of air ( the MAF in fact) at all times. And I can tell that my opening of the vanes is continuous but not "linear" whilst boost builds-up.

The last point, if I had the time and courage, would be to develop a second electronic to intercept the orders sent by the ECU to the IP, and increase the fueling only in the little zones where I had to cap the MAF until the REVs would reach the next LIMP value up, as I know there is more air than what the ECU sees. However, with the speed limits we have, and the way my old lady already drives by now, I see this as absolutely useless. as even driving up the hills, at any speed, I use very little TPS, and have plenty of spare power to use if need be.
 

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nissan patrol
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Thanks mate. Something I had noticed and mentioned to a fellow DI owner with this turbo, with heat switch on and engine running at 1200rpm the boost gauge shows 2psi, have asked him to check his numbers.
I have a standard turbo with one of those stupid positive pressure actuators. Once the engine is warm without the button on my car make 1psi pressure. I thought something was wrong with the gauge as it’s only a cheap item.


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NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
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So do I. And my chinese pressure gauge is wrong by 200mbar ( shows +1000 mbar when in fact I have +1200 mbar - and it goes <0 if ambient pressure is below 1013 mbar, which is nice though). This is why I am using the PATROL pressure sensor ( which is absolute, quite accurate and shows pressure properly even at 3000m altitude ) + an accurate barometer to manage my VNT whatever the ambient pressure is like.

MAP data is shown in green with Volts converted to mbar on the graph above. Barometer is only displayed on top of my graph. I update it every 30s, as I don't drive fast enough to make the variations of any importance in between.
 

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GUII ZD30DI Wgn
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Discussion Starter #1,745
If the vanes are very closed when Idle (too much closed in fact), it is possible that boost builds up even at such low revs.
Hi Phil, your opening line above seems to indicate my turbo is adjusted incorrectly, I beg to differ, it is spot on for my driving style, the turbo itself and conditions under which I drive.
 

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Hi Phil, your opening line above seems to indicate my turbo is adjusted incorrectly, I beg to differ, it is spot on for my driving style, the turbo itself and conditions under which I drive.
Hi Ross,
I am not saying your turbo is not adjusted properly. I don't and can't know.

I was just trying to explain to the other guys above that building too much pressure at low Revs can be due to vanes being too closed. Not that is is correct to do so. In my case, I see around 200mbar at 2000tr/mn, which I have been told is the sort of pressure I should have, and ensure the vanes management is fine in that zone and there is no back pressure. I do get 500mbar at 3000RPM and MAF 4.0V with no load, as shown on the graph, with vanes half open ( 45% pwm for MAP value, -5% for the MAP' value = 40% pwm applied to the Solenoid).

I also indicated that having just one Dawes and one needle is not sufficient to get a proper continuous opening of the vanes, (and actuatior dancing). This arrangement is NOT optimizing the airflow which is the only thing which matters as it it builds up backpressure by keeping the vanes closed until the Dawes opens. This is why you were getting a better result with the ECU and the dawes suppressing the boost peaks than with a unique Dawes+Needle arrangement. ECU opens the vanes from 300mbar on. But again, not optimum as the ECU assumes there is an EGR, and there is not, so the boost does not build up continuously as the ECU plays with the pwm signal sent to the solenoid to compensate for the opening and closing of the EGR, and to regulate the flow/the MAF value.

Certainly Digibooster brought lots of improvement to you compared to the latter, but one size can't fit all, and the setting available not sufficient to get an optimum VNT management. Setting only the min aperture of the vanes in only 4 different steps, whilst we know that 1/3rd of a turn on the limiting screw makes heaps of change to the spool-up, ( same with touching the length of the rod), is certainly better than anything else, but not optimum either. Same applies to the max aperture steps, although the value can be altered by the potentiometer. On top, the boost management strategy used in between those limits is of paramount importance, and depends upon your Patrol configuration. I have no idea of what is being used, and it is only by drawing the pwm values sent by DGBS vs boost, and the MAF value obtained that you would know. But the strategy is unique, and canno't therefore accomodate any specific configuration.

It is why I asked you some data to do this analysis, and see how much air your new turbo + DGBS are bringing compared to what I got out of the stock turbo. I am interested in all your projects, and by all safe improvements which can be brought to our beasts.

Rgds.
 

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Thanks mate. Something I had noticed and mentioned to a fellow DI owner with this turbo, with heat switch on and engine running at 1200rpm the boost gauge shows 2psi, have asked him to check his numbers.
1.3psi as per ECU readout to scangauge.

I think I may need to work on my inlet a bit more.
 

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You should compare what MAF tension you get in Neutral position at different REVs to what I get from my stock Inlet and Turbo at 2000, 2500 and 3000 (>4V) as shown on the graph above. Only air flow matters (volume of air passing through), not pressure.
It is common error I did myself in the past to believe that high pressure is nice. High volume of air, leading to ECU calculating and adding the right volume of fuel is what gives you power.
 

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2003 ZD30 Di Patrol (The rare Gold one)
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You should compare what MAF tension you get in Neutral position at different REVs to what I get from my stock Inlet and Turbo at 2000, 2500 and 3000 (>4V) as shown on the graph above. Only air flow matters (volume of air passing through), not pressure.
It is common error I did myself in the past to believe that high pressure is nice. High volume of air, leading to ECU calculating and adding the right volume of fuel is what gives you power.
Unless you change the ECU mapping so most fueling is taken care of by the MAP sensor.

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Unless you change the ECU mapping so most fueling is taken care of by the MAP sensor.

Sent from my SM-G930F using Tapatalk
For what I have understood, the ECU does not make any use of the MAP sensor to compute fueling orders to the IP, but the MAF sensor, which is why the latter is so important to our PATROL, and has to be an original one. That said, as soon as you have the VNT properly managed, the vanes accurately opened, and you do not build-up excessive back pressure, the MAF tension is homothetical to the MAP tension. That's why any of the two can be used to manage boost and the VNT.

What is really annoying with this PATROL, are the LIMP modes, again due to the ECU controlling the MAF tension vs RPM ( and by the way, MAF tension is quite proportional to RPM as can be seen on the graphs). Overcoming those by controling the MAF value at all times vs RPM as I do leads to less fuel being injected by the IP under only some driving conditions, unless, you are right, you go for a Remap.
 

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For what I have understood, the ECU does not make any use of the MAP sensor to compute fueling orders to the IP, but the MAF sensor, which is why the latter is so important to our PATROL, and has to be an original one. That said, as soon as you have the VNT properly managed, the vanes accurately opened, and you do not build-up excessive back pressure, the MAF tension is homothetical to the MAP tension. That's why any of the two can be used to manage boost and the VNT.

What is really annoying with this PATROL, are the LIMP modes, again due to the ECU controlling the MAF tension vs RPM ( and by the way, MAF tension is quite proportional to RPM as can be seen on the graphs). Overcoming those by controling the MAF value at all times vs RPM as I do leads to less fuel being injected by the IP under only some driving conditions, unless, you are right, you go for a Remap.
Yes the MAF is very important on Di engines. I spent a lot of time adjusting MAF voltages to suit my mods and driving style before remaps were available. Limp mode is dead simple to tune out on a remap by raising the expected MAF voltage in the MAF voltage/RPM map
My tune goes a bit further and applies a greater value to the MAP sensor. MAF voltage still has a part to play but it is only a small percentage. I can still easily cruise at 100kph with a dead MAF. Just need to clear the occasional code from the MAF using the ECUtalk.

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Excellent.
Having no possiblity myself to get a remap done down here, I suppressed the ECU control to the VNT, and did it with my own hw and sw, maximising the airflow at all times. And yes, I had to cap the MAF value using the RPM data letting it go up , but stay below the known limits until RPM had reached the next level up , to suppress Limp.
But still maximising fueling as MAF is otherwise reflecting the 'reality' of airflow.
And my PATROL runs like a rocket, with great fuel economy.
I also have a spare MAF on-board, so never stopped nor annoyed.
 

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GUII ZD30DI Wgn
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Discussion Starter #1,753
Be aware Phil that there is considerable difference between the early DI's and the 2003 and later MAP/ECU relationship, on my 2000 I can disconnect the MAP and the ECU doesn't care.
 

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Thank you Ross. same with mine 2000.
I did not know the 2003+ ECUs were making use of the MAP.
Talking about MAP, the nice thing is that it is an absolute sensor which provides an accurate reading even in altitude (ie negative pressure vs sea-level 1013mbar). And it runs ok until almost 22psi ( almost 1.5V output ).
That's why I used the stock sensor to manage boost.
 

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Thank you Ross. same with mine 2000.
I did not know the 2003+ ECUs were making use of the MAP.
Talking about MAP, the nice thing is that it is an absolute sensor which provides an accurate reading even in altitude (ie negative pressure vs sea-level 1013mbar). And it runs ok until almost 22psi ( almost 1.5V output ).
That's why I used the stock sensor to manage boost.
The 2003+ don't normally use the MAP. That was a extra bit of trickery to improve fuel delivery.

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ah. clear now. I was surprised the 2003 ECU would be different from the 2000. From what I know, some 3.0Di's PATROL have been produced aroind 2005 with a slightly different ECU software, displaying 160HP instead of the previous 158HP, before the CRD was introduced.
 

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GUII ZD30DI Wgn
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Discussion Starter #1,758 (Edited)
Thank you Ross. same with mine 2000.
I did not know the 2003+ ECUs were making use of the MAP.
Talking about MAP, the nice thing is that it is an absolute sensor which provides an accurate reading even in altitude (ie negative pressure vs sea-level 1013mbar). And it runs ok until almost 22psi ( almost 1.5V output ).
That's why I used the stock sensor to manage boost.
Lol, our old ECU's didn't do much more than poorly manage fuel, maybe an even worse job on EGR and boost in 'standard' condition ;).
Overall there is just no comparrison between how mine performs now and when I bought it 19 years ago, the transformation was long and hard fought for until the advent of the remap and later the new turbo, which saw a massive leap forward.
 

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if and when I have time, I will get a graph out of the DGBS I still have in a drawer somewhere, showing its pwm % vs MAP value, by connecting it in parallel to my own electronics/sw to acquire its pwm signal, and compare both behaviours on the Patrol itself. That would be of interest I guess.
 

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I read everywhere on all sites people focusing on pressure and PSI although what matters is just the volume of air and therefore to maximise the MAF value. I strongly encourage everybody to only look at this. Our original MAF sensor is quite accurate. I have two, and both give the same tension at 0.05V accuracy. so the reading is accurate.

At 2300RPM in third gear, my MAF exceeds 4V, and the boost is no more than 17psi. ( and since I have no remap, I keep the MAF tension seen by the ECU at 3.75V. ( and 3.9V below 3000RPM).

The pressure builds up continuously and gently vs RPM, and MAF goes up quick and nice too.

To achieve that, I get the actuator to "dance the rock" (purple line). The best non-electronic solution (i.e pneumatic) to match this uses three valves ( One Needle, one Dawes set to open very very early : +300mbar, followed by a second needle to regulate the quantity of pressure going through to the vacuum hose). Unlike the Dawes-Needle arrangement which keeps the vanes closed up unitl the dawes opens. In between you see pressure, but much less air ! and on top you build back-pressure).

514151
 
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