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Higher boost levels on a ZD30


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For those who wish to try higher boost levels without limp on their ZD30, particularly if you have a blocked EGR where you will see an elevation of MAF voltages (in comparison to unblocked EGR). This is the method I employed, my target being 18psi. I mounted the control box on the dash beside my ECUTalk, using double sided tape, see last pic as to reasons.

Numerous experiments had shown that upon reaching a MAF value of 3.98v under 3000 rpm would send the Troll to limp, I will go into this a little more in the second part. I purchased a Diesel Smart Fuel Cut Defender 2 (FCD2) from Rocket Industries. This device clips and holds the MAF voltage at a set-point to be determined by you, this set-point is what the ECU will see regardless of the voltage the MAF puts out. It was wired in as follows (if you are more electrically inclined than me and don't mind standing on your head under the dash then you may care to take the option of doing this on the loom at the ECU).

Extended the original FCD2 cable and pulled through the firewall, made the power and earth connection to the same points as the lift pump installation I did.

The 2 MAF/ECU remaining cables white and Blue were made to follow the original loom over to the MAF. Being a GU2 the red wire (pin 1) is the variable voltage cable, you will need to test this for yourselves to make sure, pin numbers change on various models, a thin piece of computer cable can be bent around and inserted where the MAF plugs in to check each pin and identify the correct wire by the voltage reading.

I cut the cable well below the MAF plug so as the heat soak of soldering would not travel up the wire and damage the rubber in the MAF plug.

post-91-0-08581200-1338608352_thumb.jpg

The green cable is actually the white extended, could not get white in the size I wanted, so white (green) goes to the MAF side of the cut red wire and the Blue goes to the ECU side. The connections were soldered and double shrunk to maintain the waterproof integrity.

post-91-0-42772100-1338608398_thumb.jpg

Here the wires are folded ready for wrapping.

post-91-0-03598500-1338608105_thumb.jpg

Wrapped and replugged, looks better than original.

post-91-0-42980100-1338608193_thumb.jpg

FCD2 module sitting beside ECUTalk. The plan is to leave it here (double sided taped to dash) while setting up and optimising voltages, then tucking it away under the dash.

post-91-0-31963300-1338608260_thumb.jpg

As mentioned earlier the wiring on my 2000 GUII was checked out and confirmed as follows.

Layout left to right looking at the MAF from the front of the vehicle: Pin 1 Red, Pin 2 White, Pin 3 Black, Pin 4 White, and Pin 5 empty. Remember, later models are different

Voltage testing confirmed Pin 1 Red is the MAF output.

FCD 2 wiring is,

Red to positive ign

Black to earth

White to AFM side cut in (becoming AFM Pin 1 Red in)

Blue to ECU side cut in (becoming AFM Pin 1 Red out)

Initial setting of the FCD2 dials can be carried out as follows.

Clip dial has settings 1 through 10.

Setting 1 = 3v

Setting 10 = 5.5v

Assuming voltage output is linear between setting 1 and 10 then:

Each division is assumed to = .247v

Therefore 3.86v = setting 3.5 for trial start point of clip.

Therefore 4.05v = setting 4.25 for trial start point of unclip.

EDIT: The setting dial calibration is not linear so the .247 I spoke of has no real meaning, you have to set by feel. After several VNT adjustments for spool up (this does have some impact on FCD2 setup), I have returned to my original setting of 1/2 turn down on the grub screw giving me 6psi at 1500 and 12psi at 2000.

So, I have clipped the MAF voltage at 3.88v (setting division 4) which allows me to hit 18psi under 3000rpm. Have now set up the unclip side (very easy to do under load with a small screwdriver) to activate at 3170 rpm in 4th which allows the voltage to climb to 4.27v by 3800rpm (setting division 3), the vehicle feels very good.

Edited by geeyoutoo
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This should be a good article for those with a Di, but I reckon you should also include an intro statement of what the FCD is and how it works (even though it may be in a website), as personal experience is often more valuable than advertising blurb. Also, whether this works in conjunction with dawes etc, or is a replacement for those items.

Cheers

Ray

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The MAF voltage of 3.98v that had sent the Troll to limp were found during many days of testing in 4th gear, trying to keep speed down. When the FCD2 was installed and running I found there was a significant difference between 4th and 5th gear as to this setting, in 5th it was 3.88v which I had to readjust at the FCD2.

Once running the startup FCD dial set points required raising, to achieve 3.88V limit the clip dial was adjusted up to 4.2 and the unclip to 4.6 as a safety precaution.

Further testing showed there was a secondary limp point which had not raised it's ugly head until the gaining of considerably more torque which made me lazy, this was under 2500rpm, to this day this one remains a mystery, I have reduced the MAP boost signal to the ECU and it still happens so MAP is back to original. Readjusting the VNT (total of 3/4 turn down now) to give boost readings of 5 @ 1500, 11 @2000, 15 @ 2500 have greatly reduced the incidence of limp below 2500 but I have to really push it hard under abnormal conditions to make it happen so even though I have not discovered the full reason It won't effect the vehicle. Incidentally 18psi is not achieved until just after 3000 rpm.

Interestingly this secondary limp issue does not appear to affect Auto's, so the ECU sees some difference between the manual and automatic transmission

I have not utilised the unclip function of the FCD2 yet, this allows the ECU to return to seeing higher voltages at a predetermined level, ie, if 4.1v is not seen below 3000rpm this could be used as an unclip point.

Edited by geeyoutoo
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This should be a good article for those with a Di, but I reckon you should also include an intro statement of what the FCD is and how it works (even though it may be in a website), as personal experience is often more valuable than advertising blurb. Also, whether this works in conjunction with dawes etc, or is a replacement for those items.

Cheers

Ray

Off course you are right and I have not finished writing the item up as there were a lot of twists and turns in the saga and the interesting thing is that with the benefit of hindsight this write up will be a little more condensed than on Patrol 4x4.

Edited by geeyoutoo
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As many would know I have a dual Dawes setup, 10psi low and normally 16psi high but now 18psi, I also have a DV06 needle valve which I have not used for some time after initially adjusting the VNT.

When the symptoms of limp under 2500 first occurred I was able to tune it out by adjusting the needle by 1 1/4 turns open, this lead me to believe that it was a function of the MAP that was causing it, hence my artificially reducing the boost reading to the MAP, but that wasn't the case at all................ It appeared there was another unknown, to me anyway, function of the ECU that was taking control, as though there was a timer function saying you should be at this point by this time??????

As an aside, I have noticed no difference in performance after readjusting the VNT to a lower boost ramp (going on the dyno soon, that's why I was chasing the limp so urgently) but my city fuel eco seems to have gotten better. The dual Dawes gives me improved fuel eco when set on low, I am achieving the same numbers now on high, time will tell.

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I'll be watching this with interest as my beast is not fuel friendly with high boost. It just guzzles fuel at higher boost while cruising on the highway so I've scaled it back from 17.5 psi (I had it going to limp mode as well at 100 and accelerating) down to 14 psi. Admittedly I'm using single Dawes/needle valve combo so there is no option to lower the settings for me when cruising at 100 clicks so boost would climb up and sit at 14-16 psi depending on wind load etc. hence the fuel consumption. I might have to reconsider installing another Dawes valve and dual stage solenoid to economize a bit.

I'm not sold on fiddling with VNT actuator adjustment trying to control the max spool rate and peak boost.

Cheers

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I'll be watching this with interest as my beast is not fuel friendly with high boost. It just guzzles fuel at higher boost while cruising on the highway so I've scaled it back from 17.5 psi (I had it going to limp mode as well at 100 and accelerating) down to 14 psi. Admittedly I'm using single Dawes/needle valve combo so there is no option to lower the settings for me when cruising at 100 clicks so boost would climb up and sit at 14-16 psi depending on wind load etc. hence the fuel consumption. I might have to reconsider installing another Dawes valve and dual stage solenoid to economize a bit.

I'm not sold on fiddling with VNT actuator adjustment trying to control the max spool rate and peak boost.

Cheers

It's actually quite easy, have done it 4 times now and can do it in less than 30 minutes on a cold engine and that's where I think the fuel eco in high boost mode is coming from, less aggresive spoolup with no loss of performance. As I said time will tell.

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I get a bit lost with the boost/fuel usage thing. I thought if you raised the boost you were putting in less fuel?

When i drop the boost via the needle valve the egts rise way up which i thought meant more fuel?

If i drop the boost i also lose power too.

On the highway at around 110kph my egts are around 320.

Could someone help me answer this.

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The easiest way to understand what happens when getting power out of a diesel is to start with a normally aspirated (NA) diesel engine ie non-turbo. First off, diesel engines do not have a throttle like petrol engines and with an NA diesel, air is not sucked into an engine, but is forced in by air pressure. At sea level, that air pressure is 14.7 PSI (atmospheric pressure). Diesels tend to ingest more air (oxygen) than they can burn and so to get more power, you inject more fuel, as you have excess oxygen to burn. Eventually, you will reach a point where you exceed the ability to burn more fuel and you start to produce smoke. Adding more fuel will create higher EGTs, but there is usually a reasonable safe balance.

With a turbo engine, you are able to increase the air density ie get more oxygen into the cylinder, so where you started to run out of oxygen in the NA diesel, you can keep increasing the amount of fuel being injected and get more power. But eventually, you will again reach a point where safe operating parameters will be exceeded. But where the oddity lies is that turbo diesels won't necessarily run at highest boost under full load, and can drop down a fair amount in order not to lean out the mix too much (depending on how high a boost your engine is allowed to reach). Diesels generally tend to run lean and, when cruising, will often have faily high boost and fuel/air ratios down to 1:150 (but usually not so low), which is where you get that diesel economy. That's why at cruising speeds ie low load, EGTs will usually be at their lowest.

It's a lot more complex than that, as there are many other factors involved, but that to me is the simplest way to understand what is happening with diesel combustion processes.

Cheers

Ray

Edited by Ray!
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I get a bit lost with the boost/fuel usage thing. I thought if you raised the boost you were putting in less fuel?

When i drop the boost via the needle valve the egts rise way up which i thought meant more fuel?

If i drop the boost i also lose power too.

On the highway at around 110kph my egts are around 320.

Could someone help me answer this.

This is where you need to strike a balance, aggressive spoolup, high boost all add to lower fuel eco. If I'm on a good stretch of road, coasting, I can go to low boost and marginally save fuel with EGT very slightly up, if I start to strike hills I need to go to high boost for the extra power and to keep the EGT low.

320C at 110 is very good, I run around the same maybe a little less, but with my VNT wound down my spoolup is not aggressive at all and as said appears to have impacted positively on eco.

EDIT: Just read Rays response to your question which is quite correct, the main confusing part to many people is trying to do a comparison between diesel and petrol and there is no real comparison, not sure what AFR is now for EFI petrol engines but years ago when I was building cars and racing carbureted engines we were aiming for an AFR of around 12.5 to 1 on the other hand, as Ray intimates diesels can run anywhere between 10 and 200 to 1 depending on the conditions and still manage to stay operational.

Rich on a petrol engine is cool, lean is hot the circumstances for diesel are reversed and not as critical.

Edited by geeyoutoo
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In the simplest form I always thought that more boost = more fuel = more power not to mentioned these things are directly related so less boost = less fuel = less power on the opposite side of the spectrum.

Cheers

That's the thing with diesels, it doesn't work that way. :)

Cheers

Ray

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  • 3 weeks later...

Thanks guys, that helps a bit.

I just tend to leave my needle valve on max all the time which must mean my turbo spools up pretty quick to a max of 16 pound.

It's been like this for about 4-5 years, I wonder if it is damaging my motor?

All seems good so far, it always seems to go pretty hard too especially straight off the bat.

Cheers

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  • 2 years later...

I think my troll has the MAF voltage problem as mr.nissan dealer tells me the throttle positioning sensor is faulty. Tried different pedal assembly and of course same problem. After $125 to diagnose the issue, they have no answer and are referring to mr nissan proper.

After two months of replacements of filters,cleaning EGR, adjusting dawes valve, need/seat, blocking this and that, i still limp at 3000rpm @ 12 psi up hills and overtaking. Not good when cool but much better when warm. I think is time to visit Jaycar because mr dealer says it is a ECU fault that's telling the TPS sensor is faulty when it is not!

Engine light comes on when limp mode happens.

256000 kms, 2000 model, auto, and re-built injection pump 18 months ago. EGR blanked, dawes v set @ 15psi , needle/seat, new intercooler, Swirl accuator disabled, vacuum reservoir removed.

Input welcome please!

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Unless you see those MAF voltages you're guessing but correctly as on yours boost doesn't affect the limp. Go on disconnect the boost sensor and it will still limp.

There are set points observed for limp based on RPMs, 1,950, 2,700 and 3,400. Example MAF voltages over 3.98V bellow 3,000 RPM will trigger limp. 3.65v bellow 2,000 RPM will limp.....

JDVM will allow you to tune those voltages to within 0.25 Volts at set points as required

The other way is to retard the spool up but the performance will suffer a little.

Regards

Edited by Rumcajs
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It is a very fiddly procedure and generally not recommended unless you are very desperate.

 

What you basically do is to change the adjustment of the stop screw to limit how far the vanes open. Get it wrong (reduce the length and vanes will scrape against the housing)

 

 

Some people even go that far as to change/adjust the length of the VNT actuator but I strongly caution against that because if you get it wrong you'll ruin the turbo charger. According to Garret (turbo maker) this adjustment are done on their specially calibrated bench and once disturbed can't be set correctly again. Indeed these turbos are not re-buildable because that as no one has that bench but Garret.

 

There are even Youtube videos how to do this (not on Patrol though)

 

Some people use fishing line to attach it to the "Jesus" clip on the actuator (because it has to be disconnected in order to access the stop bolt)so they don't loose it as space/access is very tight and it is easily lost.

 

Regards

 

post-9-0-74746500-1426325718_thumb.jpg

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  • 1 year later...
On June 1, 2012 at 10:48 PM, geeyoutoo said:

For those who wish to try higher boost levels without limp on their ZD30, particularly if you have a blocked EGR where you will see an elevation of MAF voltages (in comparison to unblocked EGR). This is the method I employed, my target being 18psi. I mounted the control box on the dash beside my ECUTalk, using double sided tape, see last pic as to reasons.

 

Numerous experiments had shown that upon reaching a MAF value of 3.98v under 3000 rpm would send the Troll to limp, I will go into this a little more in the second part. I purchased a Diesel Smart Fuel Cut Defender 2 (FCD2) from Rocket Industries. This device clips and holds the MAF voltage at a set-point to be determined by you, this set-point is what the ECU will see regardless of the voltage the MAF puts out. It was wired in as follows (if you are more electrically inclined than me and don't mind standing on your head under the dash then you may care to take the option of doing this on the loom at the ECU).

 

Extended the original FCD2 cable and pulled through the firewall, made the power and earth connection to the same points as the lift pump installation I did.

The 2 MAF/ECU remaining cables white and Blue were made to follow the original loom over to the MAF. Being a GU2 the red wire (pin 1) is the variable voltage cable, you will need to test this for yourselves to make sure, pin numbers change on various models, a thin piece of computer cable can be bent around and inserted where the MAF plugs in to check each pin and identify the correct wire by the voltage reading.

I cut the cable well below the MAF plug so as the heat soak of soldering would not travel up the wire and damage the rubber in the MAF plug.

 

Red Wire signal to ECU.JPG

 

The green cable is actually the white extended, could not get white in the size I wanted, so white (green) goes to the MAF side of the cut red wire and the Blue goes to the ECU side. The connections were soldered and double shrunk to maintain the waterproof integrity.

 

P1020865.JPG

 

Here the wires are folded ready for wrapping.

 

P1020866.JPG

 

Wrapped and replugged, looks better than original.

 

P1020869.JPG

 

FCD2 module sitting beside ECUTalk. The plan is to leave it here (double sided taped to dash) while setting up and optimising voltages, then tucking it away under the dash.

 

P1020872.JPG

 

As mentioned earlier the wiring on my 2000 GUII was checked out and confirmed as follows.

 

Layout left to right looking at the MAF from the front of the vehicle: Pin 1 Red, Pin 2 White, Pin 3 Black, Pin 4 White, and Pin 5 empty. Remember, later models are different

 

Voltage testing confirmed Pin 1 Red is the MAF output.

 

FCD 2 wiring is,

Red to positive ign

Black to earth

White to AFM side cut in (becoming AFM Pin 1 Red in)

Blue to ECU side cut in (becoming AFM Pin 1 Red out)

 

Initial setting of the FCD2 dials can be carried out as follows.

Clip dial has settings 1 through 10.

Setting 1 = 3v

Setting 10 = 5.5v

Assuming voltage output is linear between setting 1 and 10 then:

Each division is assumed to = .247v

Therefore 3.86v = setting 3.5 for trial start point of clip.

Therefore 4.05v = setting 4.25 for trial start point of unclip.

 

EDIT: The setting dial calibration is not linear so the .247 I spoke of has no real meaning, you have to set by feel. After several VNT adjustments for spool up (this does have some impact on FCD2 setup), I have returned to my original setting of 1/2 turn down on the grub screw giving me 6psi at 1500 and 12psi at 2000.

 

So, I have clipped the MAF voltage at 3.88v (setting division 4) which allows me to hit 18psi under 3000rpm. Have now set up the unclip side (very easy to do under load with a small screwdriver) to activate at 3170 rpm in 4th which allows the voltage to climb to 4.27v by 3800rpm (setting division 3), the vehicle feels very good.

Has anyone try the FCD-2 from turbo smart and confirm this device acctualy clamps the maf sensor voltage to eliminate the limp mode due to higher voltage? 

My limp mode is at 120 km 3,000 rpm and we strongly believe is the maf voltage is going higher 3.98 v so anyone can confirm the fcd-2 is the path to follow and confirm if this eliminate the limp mode?

also do i need a fcd-1 for the map or with the fcd-2 for the maf is ok?

my dawes vale are at 15 psi and my car enter in limp mode at 120 km between 2,500 and 3,000 rpm.

im just looking concirmatio before puchase the fcd-2 from turbo smart.

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Hi Mate, PM sent with email address, I don't use this system anymore I work with another system which gives me good step-less limp control, After a few mods I finished up with 3 limp zones of which the FCD could only control 1, now I can control all limp zones plus add fuel to other areas, it has worked very well for quite a few years now and I have built well over 20 of them for guy's in Australia, various parts of Europe and South America.

Cheers
Rosco
 

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