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NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
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Discussion Starter · #581 · (Edited)
Works beautifully.
I love electronics and software when they assist in getting the most out of mechanical components.

Here is what I now get when I unplug my MAF and switch Dip-switch 4 to 'ON'. ( Don't do that on your MB as you don't have the new firmware. But you can try to unplug your MAF and check how your Patrol drives with no MAF, with the current firmware).

MB reads something like the TPS value out of MAF_in "in the air". So the ECU will not notice. No MIL code, better than what the ECU does (security mode), but since the TPS voltage is on average less than what you can get out of a working MAF when your turbo map is well tuned, I can't say it is a perfect "work-around" for when you MAF is down. But it "sort of works". Just bear in mind that the more you press the throttle, the more MB ( and your ECU) will read a higher "MAF" voltage. However, when idling, the voltage will remain low ( 0.5V instead of 1.6V to 2.0V). Better than nothing. But far from perfect.

I have now tested a true "MAF failure mode" function. My Patrol almost drive the same, as the MB "estimate" of the MAF voltage is very close to what a working MAF would deliver.

With an unplugged MAF, below is (dark blue - bottom graph) the MAF_in data ( almost identical to TPS - beware of the different Y scales), and in light blue the "MB-estimated MAF' provided to my ECU. I did not think it would be that good, and almost unoticeable when I drive.

Nature Slope Infrastructure Purple Rectangle


Of course this suppose that your turbo map is well tuned. And MB continues to take care of any limp since I have no remap, hence the MAF voltage which is above the limp thresholds when pushing gears.
 

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NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
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1,532 Posts
Discussion Starter · #582 · (Edited)
More info on our Patrols for MB owners.
Something many do not realize, is that the Solenoid ( and therefore the VNT as a consequence) is quite sensitive to the battery + alternator voltage.

All MB owners know that the Solenoid is controlled by a "pwm" signal which allows to digitally generate a variable voltage to control the solenoid and therefore the vanes aperture.

In fact the "pwm control" acts a bit like a "pourcentage".

If your battery + alternator voltage varies, so will the voltage applied to your solenoid and therefore the vanes aperture for a given pwm value.

I replaced my alternator recently from the stock Hitachi, to a different one. Whilst I had before a steady 14.4V power supply all the time, once my motor was ON, I am now get something between 14.1 and 14.4V, depending upon the battery load (less voltage when battery is fully loaded).

No need to say that, for example, 48% x 14.4 = 6,91V is >> 48% x 14.1 = 6,77V.
It means that if you set your map for a 14.4V voltage, your 48% applied to a lower 14.1V is equivalent to a 47% applied to 14.4V or 1% less. It is significant enough to require attention.

Similarly, @trev zd30 reported an issue he had with his dual battery set and coupler, with the voltage varying significantly over time. In fact, I had a look at what a coupler like Citrix does, and it appears that first it loads the main battery at start-up, then, when the main battery is loaded, it waits for a delay of 10' before loading the auxiliary. That in itself leads to a varying voltage over an extended period of time, which impacts the solenoid, therefore your VNT, therefore the airflow, therefore the power your Patrol delivers.

In that case, you can introduce a step-up step-down power supply regulator on the +12V / Gnd lines of your MB ( and select the 13.8V version, not the 12V, to minimize the mods you will need to apply to your turbo map).

A stable 13.8V will remove any voltage "variability" due to alternator or coupler, and provide a constant turbo performance as defined by your turbo map.

@Richie-Rich is in the process of tuning its map to better drive his Eclipse-fitted and remapped CRD, and experiencing the same issue. So if you do have a coupler, make sure your alternator delivers a steady voltage after a few minutes of warming up.

Rgds all.
 

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I can shed some further light on this. No idea why but since I have replaced the alternator I too have suffered wandering voltage. 13.5-14.2 is the operating range these days.

Could not for the life of me work out why my car would feel so different at times. Thought I was going mad. Thanks to Trev and Phil and the awesome Mb software we were able to work out what was happening. The voltage regulator is now on its way.

Whist I am writing I might as well state that this is by far the best mod I have done to my Patrol. It can be a bit daunting and certainly without Phil and Trev to point me in the right direction it could have been a bit frustrating, but the Patrol has never been as enjoyable to drive. The Eclipse turbo is finally working how it should. There is zero lag, it just pulls. The EGT’s are under control and finally it is back to being frugal. Absolutely loving it.
 

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NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
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1,532 Posts
Discussion Starter · #584 · (Edited)
Further to Rich's post, I'll add another info of interest to MB owners making use of cruise control :

When cruise control is 'ON', the "load" is managed by your ECU ( for the stock cruise control function only). As a result, the TPS voltage is meaningless to MB.

As you know, MB is fitted with a turbo surge avoidance function, opening vanes shortly when changing gear. If you see any "pumping effect" when using cruise control, it can be easily fixed by simply raising the absolute MAP_T value from its factory value ( between 21 and 22 psi absolute) to around 29 psi.

To do so, use the special keys indicated below.
'Y' & 'V' which increase or decrease the MAP_T Threshold value.
 
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