Patrol 4x4 - Nissan Patrol Forum banner

1 - 20 of 32 Posts

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #1 (Edited)
Hi all,
please correct me if I am wrong.

The comp-map I found for the GT 2052 garett turbo is not the right one apparently for our GT2052V (?), nevertheless, I will base my reasoning on it.

I have added my comments on the flow diagram below, which explains how and why you can get LESS airflow with MORE boost if you are not carefull :

516242


The right limit on this kind of diagram shows, no matter what you do to increase boost ( like keeping the vanes closed ... see my post one Dawes - two needles), there is an inherent limit which can't be overcome, due to the comp wheel size and design. On this particular turbo, the maximum flow of air is obtained at 1.25 bar boost ( if I read the diagram well, as "pressure ratio" is apparently the ratio between the absolute boost measured divided by the ambiant pressure (1000bar at sea level). If you go higher, it is just additional wear and tear for your turbo. No more.

The best efficiency is by the way obtained when you stay within the light blue area (77% here) I have drawn on the graph.
So the turbo vanes opening/closing should be managed to remain as much as possible in that zone, with therefore a steady an continuous increase of airflow with boost (and Revs...).
There is no need to build too much boost, as it will not increase airflow, nor to build it up too quickly, as you loose efficiency.

Most probably, if you have a stock turbo, and if you have 18 psi at, say, 1700- rpm, you may NOT be in the best efficiency area. You will see high boost on your gauge, but you might not have the highest MAF value.

That said, if you can get the same MAF value with less boost, ... why would you push the speed of the comp wheel of your turbo up, and get hotter air in your motor, knowing that it will not help you much and have no, or even negative, effect on your MAF voltage ?

Now, you can make the same reasoning with any other turbo, providing you get the manufacturer data, and try and maximize your airflow (MAF value). Be carefull though the stock MAF saturates at 4.5V maximum, and the stock turbo can get enough air in to get the stok MAF close to that maximum.

You will therefore need a larger range one with a new and modern turbo, or you won't be able to use it at its best.
 

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #2
I extracted MAP vs MAF voltage from the data I have collected. I'll have to capture both MAF and MAP accelerating on each gear to capture complete graphs, but what I get is interesting on my Garett turbo :
Nice line, with 2.9V at 0.2 bar boost and 4.3 V at 1.2bar boost (17psi roughly). It would fit nicely on the curve above.
What I don't know though is how to translate the stock MAF voltage into lbs/min.
If you have the info, please tell me.

I like this.

516243
 

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #3
Down low, this is what I get with my stock turbo and stock inlet. I have added the RPM data at 3 points.

You will notice that my MAF exceeds 3.55V well below 2000RPM (1640RPM precisely here), with a small 3 psi boost. Just getting the vanes to open early, at an 'optimum' setting.

So again, with the stock turbo, no need to get high boost at low revs. You won't get more air, just less. Get a good spool-up to help the turbo spin, and just make you vanes to open very soon, as soon as some boost starts to build-up.

You have a bigger turbo, and/or bigger inlet ? Look for the best setting : open your vanes a the 'right moment', and never too late, get more air in, and your MAF to the roof !

516270
 

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #4
Some of you might want ot learn a bit more about their turbo and their ECU.

If you have a cable, and ECUTALK running on a PC, you might be able to acquire RPM, MAF, and VNTurbo SV1 vs time, and then import the data in an Excel spreadsheet. Unfortunately, you cannot import MAP, as this sensor is not available on the interface. So you need a specific hw and sw to do so.

Do not tick other boxes, as the interface only runs at 9600bits/s, and the sample rate decreases as the number of sensors requested increases.

I found an old file from the time when I was trying to understand how the ECU manages the VNT through the solenoid.
This is it, accelerating from 1800 RPM to 2700 RPM in gear 4 (manual T), after a change of gear from 3 to 4.
TPS is less than 2V ( so 'medium' pressure on the pedal). The line on the curve is TPS (Volts) x 20, as I only have two Y scales available. Right scale is used for RPMs. Left for Solenoid pwm control command in %. (green line).

The pwm control command sent by the ECU to the Solenoid ( even if you use valves, the ECU still computes as it is not aware of any of you mods), is 55.9% pwm at sea level ( this corresponds to the % of the time the 'minus' wire of the Solenoid is grounded , and therefore the Solenoid is power-supplied) for vanes fully closed, and 20% pwm, for vanes fully opened.

Guess what, the pwm control command is between 33% and 38% all the time, so around mid-aperture ( or closure) of the vanes. as explained above.

When theory, and reality, meet... hands-on experience.

516320


If you have modified your PATROL, and/or your Inlet, exhaust, or replaced your turbo, you can have a look at your RPM and MAF voltage vs time data, with a special zoom down low, as this is where the difference can be made.
 

·
Registered
CRD Wagon
Joined
·
849 Posts
Some of you might want ot learn a bit more about their turbo and their ECU.

If you have a cable, and ECUTALK running on a PC, you might be able to acquire RPM, MAF, and VNTurbo SV1 vs time, and then import the data in an Excel spreadsheet. Unfortunately, you cannot import MAP, as this sensor is not available on the interface. So you need a specific hw and sw to do so.

Do not tick other boxes, as the interface only runs at 9600bits/s, and the sample rate decreases as the number of sensors requested increases.

I found an old file from the time when I was trying to understand how the ECU manages the VNT through the solenoid.
This is it, accelerating from 1800 RPM to 2700 RPM in gear 4 (manual T), after a change of gear from 3 to 4.
TPS is less than 2V ( so 'medium' pressure on the pedal). The line on the curve is TPS (Volts) x 20, as I only have two Y scales available. Right scale is used for RPMs. Left for Solenoid pwm control command in %. (green line).

The pwm control command sent by the ECU to the Solenoid ( even if you use valves, the ECU still computes as it is not aware of any of you mods), is 55.9% pwm at sea level ( this corresponds to the % of the time the 'minus' wire of the Solenoid is grounded , and therefore the Solenoid is power-supplied) for vanes fully closed, and 20% pwm, for vanes fully opened.

Guess what, the pwm control command is between 33% and 38% all the time, so around mid-aperture ( or closure) of the vanes. as explained above.

When theory, and reality, meet... hands-on experience.

View attachment 516320

If you have modified your PATROL, and/or your Inlet, exhaust, or replaced your turbo, you can have a look at your RPM and MAF voltage vs time data, with a special zoom down low, as this is where the difference can be made.
Interesting findings. I was just discussing with another member around 2 weeks ago when your original thread was going that this would be interesting to know what logic the ECU uses to drive the vac sol.

Further it would also be interesting to model this at low TPS vs WOT TPS.
 

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #6 (Edited)
With ECUTalk and consult cable you can acquire TPS, RPM and vacsol pwm control from ECU to analyse what you want mate.
Edit :
Be aware though that since your ECU does not know your EGR is blocked, it keeps on opening and closing the vanes when opening and closing the swirl valve to compensate for the additional (or decrease) of flow. That is very visible on the data. So don't be misled.

ECU also opens quite wide the vanes when releasing the pedal depending upon the TPS value, to avoid surge.

All that is lost when you use valves. But not an issue at all if you use Dawes/Tillix + 2 Needles, even if, as I have reported, it is not THE optimum.

Last but not least, the logic is simple : get the best efficiency/ Airflow to your motor at all times, as per the turbo MAP.
 

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #7
Addition to this thread.

I am in the process of modifying my acquisition software to be able to modify my VNT management 'map' in real time whilst driving. What a luxury !

If only I could do the same with fueling and timing on my old lady, I would be in full control. That will take me some more time, but I am thinking of it since remap is not available close to where I live.

I was running up to now 18 psi max boost, and investigated the effect of opening slightly more the vanes a bit earlier. Guess what : a bit less boost, but more air still ! I get 4.38V as early as 3186RPM, with 16.4 psi max. Great.

Forget once for all about building huge boost. Just keep in mind what your cylinders need is as simple as "AIR + DIESEL".

516990


In addition, I have put back my vanes opening for 300ms when changing gear to suppress any surge, which can happen when the vanes close too quickly ( at "pedal-up" ) , as described by @OldMav. ( you can hear that high frequency sort of 'overboost noise' ... ).

I still had a bit of it when driving up-hills in the mountains as my spool-up was quite agressive (in MAF value increase, not in boost... same story) .

I hope my explanations are clear enough.

End of thread.
 

·
Registered
'14 Y61 ZD30 CRD M/T ST
Joined
·
1,704 Posts
I'm probably going to create more confusion than anything else, but I had a little play and thought I'd put some results here.

I did a few runs yesterday with my CRD for comparison. Third gear, full throttle from around idle up to max rpm on a flat road. Data sampled at 10ms, but I could probably open this up a bit as it seems like not much changes in a 150ms period.

Engine is stock. No EGR block, no needle valve(s), no ECU reflash, std exhaust, std turbo. Car has about 13,000km on the ODO. Only change to the drivetrain is a set of 33" tyres, which I think is irrelevant in this case.

First graph shows MAP [kPa] & MAF [mg/st] against Engine Speed [r/min] and Time [ms]. The most interesting part for me is the very similar shape of the curves, which makes me think the factory ECU manages boost fairly well, at least in a steady state condition.
517038


Second graph shows the same MAP data vs. Turbo Charger Variable Nozzle Control Valve Position [%]. Don't really know what to make of this... o_O
517039


@Phdv61 if you're interested in more data for a CRD, or want to "teach me" what I'm measuring and how to interpret it, let me know. Unfortunately, like you, I don't know what the relationship is between MAF [voltage], [lbs/min] or [mg/st]. I presume mg/st is miligrams per stroke...? If so, would "stroke" be inlet strokes? I.e. for a 4-cyl, 4-stroke engine, is that 2 inlet strokes per engine revolution?

I tried to replicate the MAP vs MAF graph, but I get some weird results. This graph, shows MAP vs MAF up to the point where the MAP peaks (~1,800r/min).
517043


Beyond this boost peak (up to max rpm), things get a bit all over the place...
517044
 

·
Administrator
GUII ZD30DI Wgn
Joined
·
44,008 Posts
I don't understand all the graphs myself either but, it is recognised from experience that the CRD manages boost and just about everything else far better than the old DI, especially the models Phil and I own, we went to all sorts of lengths here years ago to improve how the ECU handles just about everything on them.
 

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #10
Hi @AndrieK
Thank you so much for this set of data. If you could post the .csv file and your excel file, it would be great, and I will be able to explain further.

I doubt you can get one sample every 10ms through your OBD2 interface. Did you check the time in ms between two samples ?
As you can see on your graphs, data seem not to change several samples in a raw. So maybe 10ms is beyond what the ECU may be able to refresh on the interface. To be checked. Not a big deal though.

Interesting thing is that the max boost is reached at 1820RPM with VACSOL at 36%pwm. That is coherent with what I do. However, the square signal you get on your graph for VACSOL is wrong for reasons I need to understand. It might be due to the way the interface is managed by the ECU. but there is no reason to vary the pwm command to the vacsol that way. I hope it is not what the VACSOL receives... even if on average it is correct.

As a reminder, on the Patrol 55.9% pwm ( x 14V) to the stock vacsol gets the vanes closed to the maximum allowed by the limiting screw. 20% pwm is vanes fully opened. so 40% is around mi-aperture.

From 820 to 1600 roughly, the vanes are opened very slowly, then much more rapidly to contain the increase of boost, until it reaches the 1.1 bar boost (roughly). At that point, the vanes opening is around 38%. ( 50% opening as I have ecplained elsewhere : the best turbo efficiency zone). Then, the VNT map is such that the ECU is trying to maintain that level of boost by acting on the pwm command to the vacsol. So it starts by opening the vanes little by little again... In fact, it is exactly what I am doing on my ZD30. Funny... but not surprising to me.

Beyond 3000RPM the boost and MAF tend to decrease, and the vanes are closed a bit more little by little as MAF/MAP decrease. Not unusual on a fully stock engine. and on all Diiesel.

So no confusion whatsoever. All the opposite. As @geeyoutoo said, our ZD30 is different from the CRD, and I am glad to see this curve and be able to compare. what clever engineers have done, and what a beginner like me discovered through hands-on testing.

What is strange though, is that I do not see the swirl opening, and the EGR effect on the VACSOL graph, nor the MAF one. What gear were you on ? what conditions ? ( flat road, wind ?).

Your acquisition shows 700 mg of air/stroke. 1 liter of air is roughly 1290 mg at ambiant pressure. So you get at 820 RPM 1290mg / 700mg Liter of air per stroke which is ... 1.8 Liter. so a bit more than the 1.5 Liter at idle.

At idle, a 3L motor with no boost, ambiant pressure gets around 3.2lbs/mn of air :
750 RPM = 12,5Hz. Air weight is 1.29g/L. - 6.25 x 3L = 18.7 x 1,29g / s = 24g/s or 3.21 lbs/mn
You can now convert the units on your graph if you wish.
 

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #11
One last comment before I forget.
If my reading of your curve is correct, the MAP vs MAF is built using the data from 750 to 1820 RPM, RPM at which the MAF reaches its max value. mg/stroke is twice as much than what you have at idle.
but RPM is 1820, so, per second, the quantity ( volume) of air you get per second is x 2 x 1820/750 = 4.85 tims more.
That is to say 4,85 x 3,21 = 15,6 lbs/min. You can see where you stand on the Garrett turbo MAP which is posted elsewhere. That is less than what I get on my ZD30, but I have an EGR blocked and a 3" exhaust, and a different vanes management. But all data are really coherent. That is great.

So again thank you for this valuable input helping me to progress further my understanding of our ladies.
 

·
Registered
'14 Y61 ZD30 CRD M/T ST
Joined
·
1,704 Posts
Phil, I am glad the data makes sense to you and thank you for giving your interpretation. I'd have to spend a bit of time to digest it all. I will send you the raw data via PM.

As I mentioned earlier, the run was done in 3rd gear (M/T) on a flat road at full throttle. I basically drove at around 20-30km/h, selected 3rd and coasted (zero throtttle) until engine rpm drops to around idle. I would then trigger the log and immediately apply full throttle. Then keep it there until the red line, release the throttle and coast down (still in 3rd) until back down to around idle.

Luckily not far from where I live, there is a perfectly flat, straight piece of road with very little traffic. Ideal for this type of testing.

The data in the graphs DO NOT represent the coast down from max rpm to idle. Only the acceleration portion.But the csv files contain all the data.

If anyone else wants the raw data, let me know and I'll post it here.
 

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #13 (Edited)
Hi again @AndrieK,
here are the two extreme points drawn on the garrett turbo Map.
Nissan engineers worked well on the CRD apparently, even if there is still some power left-over.

On your MAP vs MAF curve, beyond 1820RPM, you say the data comes all over the place.
If you change unit and go to mg/s or lbs/min, it will not as RPM will be taken into account ( you have more stroke/s as RPM goes up... easy to do with Excel.
You'll then be able to superimpose all your data on the Garrett turbo MAP, for all RPMs.

Note : with all that done, you will see that you can push a bit more air in... and get a bit more power
 

Attachments

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #15
Hi again @AndrieK,
This is the MAP ( boost converted to bar) vs MAF ( converted into lbs/min) for your town driving file you sent me.
All point are drawn, so accelerating of decelerating.

517066
 

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #16
And this is the graph for the file from which you extracted your own graphs, with all data converted and drawn.
Quite nice.

I took 1000mbar for ambiant pressure to convert absolute in relative, but in fact, it was a bit less ( can be seen on lowest MAP values at idle in your file)

517067
 

·
Registered
Was known as JT54_Y61 GU IV 08CRD Wag ST
Joined
·
147 Posts
@Phdv61 The gauged boost pressure (bar) vs MAF(lbs/min) (post #16) graph you presented from data as supplied @AndrieK, are you able to provide the mean X-Y coordinates with associated RPM, so that I can compare against my raw data for CRD fitted h/f turbo and upgrade induction. Raw data that I have been recording is MAP (absolute_kPa) and MAF(g/s) at specific RPM (1000-2000 in 100RPM increments and 2500, 3000, 3500RPMs.

I can convert from what you can provide. Thanks, John
 

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #19 (Edited)
I did this for you, but it took me an hour to edit by hand the Excel spreadsheet.

@AndrieK ,
RPM data only changes every 150ms in your acquired file. No need to get a quicker flow. I have suppressed all data in between as they were meaningless. That indirectly taught me that the ECU may not execute its limp control quicker than every 150ms. Interesting.

@Bidja ,
Here is what you requested. please note that the Patrol in question is full stock.
But it provides a comparison. I hope I did not do any mistake in the units conversion.
But 20g/s seems right at a RPM close to 'idle'.

The VNT on this 2014 CRD Patrol seems to be managed the same way it is on most "modern cars". I'd like to know though the boost level at a constant speed of 80km/h and 110km/h GPS on a flat road with no wind to keep a reference from a stock CRD.


517071


Here are the data it is coming from, and as provided by @AndrieK , 3rd gear, full throttle from 828 to 4130 RPM continuous increase ( although the RPM as measured by the ECU is a bit erratic/noisy vs time). Pwm value shown, even if correct on average, is weird. ( there may be a problem in the ECU software itself and/or the sampling of these, as this constant 'wave' is abnormal).

517072


Enjoy !

EDIT : I think I have understood why I don't see the swirl solenoid / EGR opening on the graphs above : at full throttle, most probably the ECU does not open the EGR to allow max power.
 

·
Registered
NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
Joined
·
489 Posts
Discussion Starter #20 (Edited)
I have 'averaged' the pwm value over 8 samples to get a graph which can be read.
It is interesting to see how the vanes are managed vs RPM, boost and MAF value. Very similar ( but not identical since my configuration is non stock, and different) to what I do with my electronics. Per the book and theory, not surprisingly. It can be 'copied' with valves though, as explained elsewhere in my posts, for those who have a blocked EGR and modified exhausts/ turbos.... But it will never be as "perfect' as what electronics and sw can provide.

Even if some dislike it or strongly believe otherwise, this is the (real) way a VNT must be managed to provide efficiency and air : vanes must be open slightly from ... boost zero ! Design engineers are not (always) stupid.

A simple needle, quite closed, connected to the boost line one one side, and to the actuator on the other can do that. And then, you set your dawes or Tillix to open as early as 300mbar ( or 400 or 500 depending upon your configuration- see below on the graph how the CRD works...) followed by a Needle to limit the quantity of positive flow injected in the vacuum, therefore providing a more continuous opening of the vanes with boost and RPM. Simple.

517074
 
1 - 20 of 32 Posts
Top