Possible MAF mod
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Reducing the MAF value seen by the ECU reduces the Fuel injection, and therefore reduces power. So it has to be done with care as I am sure you do.
Unless you do a remapping removing the ECU limp modes values ( not easy to find remappers taking the risk to unsolder/remove the PROMs from the ECU in my country), the best way is to have electronics acquiring both MAF voltage AND RPM, and modifying the MAF value sent to the ECU, keeping the voltage under the maximum allowed by the ECU for a given RPM.
3.55V maximum under 2000RPM, 3,88V under 2500RPM, 3.98V under 3000RPM, and 4.2V under 3500RPM.
![519403]()
of course more power would be available if fueling would be increased, without getting any smoke, in the zones where much more air is available than what the ECU effectively sees. A chip could provide that if remapping is not available.
Unless you do a remapping removing the ECU limp modes values ( not easy to find remappers taking the risk to unsolder/remove the PROMs from the ECU in my country), the best way is to have electronics acquiring both MAF voltage AND RPM, and modifying the MAF value sent to the ECU, keeping the voltage under the maximum allowed by the ECU for a given RPM.
3.55V maximum under 2000RPM, 3,88V under 2500RPM, 3.98V under 3000RPM, and 4.2V under 3500RPM.
of course more power would be available if fueling would be increased, without getting any smoke, in the zones where much more air is available than what the ECU effectively sees. A chip could provide that if remapping is not available.
these are my testimonies at the factory MAF, at the parking lot.
excellent fuel consumption and traction, 35-inch wheels, 4.88 pairs
![519406]()
made some measurements in motion, in high gear under load uphill
temperature overboard +25
speed - 2000
speed-100km \ h
MAF-3.06
rpm-2500
speed-120km \ h
MAF-3.46
rpm-3000
MAF-3.68
temperature -91gr
temperature of exhaust gases 600 gr.
excellent fuel consumption and traction, 35-inch wheels, 4.88 pairs
made some measurements in motion, in high gear under load uphill
temperature overboard +25
speed - 2000
speed-100km \ h
MAF-3.06
rpm-2500
speed-120km \ h
MAF-3.46
rpm-3000
MAF-3.68
temperature -91gr
temperature of exhaust gases 600 gr.
Attachments
Hi Nikolai,
with such low MAF values, it is normal to have an excellent fuel consumption, but you certainly leave a lot of power 'on the table'.
Initially, when I bumped into limp mode, I had to put three schottky diodes in serie on the MAF signal before it enters the ECU to decrease its value by 0.35V roughly, and stay all the time below the limp modes 'thresholds' given above.
With my new arangement, and a better electronic MAF-RPM control, it does not compare with what I had before.
If your electronics allow you to increase the MAF value vs RPM, you should try and increase it, staying under the limp modes threshold, to recover the power you have lost.
My fuel ECO when driving in Corsica ( from mountains down to the sea, and vice-versa) stays under 9L/100km.
with such low MAF values, it is normal to have an excellent fuel consumption, but you certainly leave a lot of power 'on the table'.
Initially, when I bumped into limp mode, I had to put three schottky diodes in serie on the MAF signal before it enters the ECU to decrease its value by 0.35V roughly, and stay all the time below the limp modes 'thresholds' given above.
With my new arangement, and a better electronic MAF-RPM control, it does not compare with what I had before.
If your electronics allow you to increase the MAF value vs RPM, you should try and increase it, staying under the limp modes threshold, to recover the power you have lost.
My fuel ECO when driving in Corsica ( from mountains down to the sea, and vice-versa) stays under 9L/100km.
This is my Arduino piece of code to keep the MAF value under control vs RPM, in idle mode and above (sorry for the french comments)
//****//
{ //* M A F_in analyse et traitement des mises en sécurité ECU *//
//***//
moteur_arrete = false;
if (RPM <= 600 ) valeur = MAF_Memory_in; // pas de signal RPM -> MAF_out = MAF_in
else
{
if (MAF_Voltage_int <= 2.20) valeur = 1.80; // on force la sortie MAF à 1.80V fixe et stable;
// De 2.20V on passera à 1.80V soit - 0.40 V au ralenti
// jusque 2,80 Volts en input, on rejoint linéairement la courbe MAF_in :
else if (MAF_Voltage_int < 2.80) valeur = 1.80 + (MAF_Voltage_int - 2.20) * 1.66667 ;
else valeur = MAF_Voltage_int;
/* Traitement des mises en sécurité */
/* il faut vérifier que la tension MAF n'est pas */
/* - au dessus de 3.55V en dessous de 2000tr/mn */
/* - au dessus de 3.78V en dessous de 2500tr/mn */
/* - au dessus de 3.98V en dessous de 3000tr/mn */
/* - au dessus de 4.20V en dessous de 3500tr/mn */
if (RPM <= 2010.0) { if (valeur > 3.53) valeur = 3.53;}
else if (RPM <= 2510.0) { if (valeur > 3.86) valeur = 3.86;}
else if (RPM <= 3010.0) { if (valeur > 3.96) valeur = 3.96;}
else if (RPM <= 3510.0) { if (valeur > 4.18) valeur = 4.18;}
}
}
- "RPM" contains RPM value,
- "MAF_Memory" in contains 60ms square-averaged values of MAF voltage data,
- "MAF_Voltage_int" contains 120ms square-averaged values of MAF volttage data
- "valeur" contains the MAF_out voltage value to be sent to the ECU.
//****//
{ //* M A F_in analyse et traitement des mises en sécurité ECU *//
//***//
moteur_arrete = false;
if (RPM <= 600 ) valeur = MAF_Memory_in; // pas de signal RPM -> MAF_out = MAF_in
else
{
if (MAF_Voltage_int <= 2.20) valeur = 1.80; // on force la sortie MAF à 1.80V fixe et stable;
// De 2.20V on passera à 1.80V soit - 0.40 V au ralenti
// jusque 2,80 Volts en input, on rejoint linéairement la courbe MAF_in :
else if (MAF_Voltage_int < 2.80) valeur = 1.80 + (MAF_Voltage_int - 2.20) * 1.66667 ;
else valeur = MAF_Voltage_int;
/* Traitement des mises en sécurité */
/* il faut vérifier que la tension MAF n'est pas */
/* - au dessus de 3.55V en dessous de 2000tr/mn */
/* - au dessus de 3.78V en dessous de 2500tr/mn */
/* - au dessus de 3.98V en dessous de 3000tr/mn */
/* - au dessus de 4.20V en dessous de 3500tr/mn */
if (RPM <= 2010.0) { if (valeur > 3.53) valeur = 3.53;}
else if (RPM <= 2510.0) { if (valeur > 3.86) valeur = 3.86;}
else if (RPM <= 3010.0) { if (valeur > 3.96) valeur = 3.96;}
else if (RPM <= 3510.0) { if (valeur > 4.18) valeur = 4.18;}
}
}
engine control and MAF are different, on machines of 2004 onwards, if my MAF shows 3.8-4 volts for 10 seconds, the control unit will block the fuel supply
we very rarely have problems with the Restayl car from 2004, but there are a lot of problems with the cars until 2004, so we rearrange the MAF and the control unit from Restayl and the problem with power loss goes away
we very rarely have problems with the Restayl car from 2004, but there are a lot of problems with the cars until 2004, so we rearrange the MAF and the control unit from Restayl and the problem with power loss goes away
No, They are not different between 2000 and 2004 included.
if you have a problem at 3.8 - 4V, it is just due to the MAF voltage exceeding 3.88V whilst you are under 2500RPM, and/or or 3.98V whilst you are still below 3000RPM.
And I can ensure you that 4.4V above 3500RPM is not at all an issue.
Hence the way MAF control is to be done 'ideally' when you cannot access REMAP, using the 'Arduino' trick I was mentioning earlier. Arduino + some electronic components+ software.
if you have a problem at 3.8 - 4V, it is just due to the MAF voltage exceeding 3.88V whilst you are under 2500RPM, and/or or 3.98V whilst you are still below 3000RPM.
And I can ensure you that 4.4V above 3500RPM is not at all an issue.
Hence the way MAF control is to be done 'ideally' when you cannot access REMAP, using the 'Arduino' trick I was mentioning earlier. Arduino + some electronic components+ software.
If I remember well, some 3.0 Di PATROLs until 2006 have 4 contacts MAF, but from 2004 onwards some also have 5 contacts MAF with an additional temp sensor . So the ECU software is necessarily different to take air temp (ie density) into account.
But I believe limp modes management ( MAF voltage allowed vs RPM ) remains similar.
Record MAF vs RPM if you can, and you will see the exact RPM-MAF couple at which you get your limp.
ex : some get limp at 2400 RPM under load as their MAF exceed 3.88V at that moment, others get limp at 2750 RPM as their MAF exceeds 3.98V at that moment. The RPM at which you get limp depends upon the load, as the more you press the throttle, the more fuel is injected, the more the turbo spins, and the more air gets in.
But I believe limp modes management ( MAF voltage allowed vs RPM ) remains similar.
Record MAF vs RPM if you can, and you will see the exact RPM-MAF couple at which you get your limp.
ex : some get limp at 2400 RPM under load as their MAF exceed 3.88V at that moment, others get limp at 2750 RPM as their MAF exceeds 3.98V at that moment. The RPM at which you get limp depends upon the load, as the more you press the throttle, the more fuel is injected, the more the turbo spins, and the more air gets in.
no, since 2004 all cars in europe have other nozzles, fuel injection pumps and laf.
The MAF is different in mounting and is similar to the MAF with pit finder, x-trail, patol 62, but the main thing is the other control unit, for Russia, for sure, cars from 2004 practically do not suffer from the problem of increased voltage
The MAF is different in mounting and is similar to the MAF with pit finder, x-trail, patol 62, but the main thing is the other control unit, for Russia, for sure, cars from 2004 practically do not suffer from the problem of increased voltage
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3 Posts
Greetings everyone, thank you for the interesting topic. Does some one have 5 pin MAF on pre 2004 vehicle, are they good to use. Quality brands offered in my country are mostly 5 pin versions and 4 pins are mostly cheap ones that I don't want to spend money on. Thanks.
buy a genuine Nissan MAF if you don’t want to bump into problems.
cheapest is from Amayama in Japon. comes in 10 days. 90 Euros. buy from their web site. you might need to pay taxes on arrival in your country.
it looks like MAF voltage vs quantity of air is quite different from earlier Di (4 pins) to CRD (5 pins). the 5pins has one more to accommodate a temp sensor, used by the CRD ÉCM but not by the Di ÉCM.
a 4 pins Nissan Maxima MAF may work on the Di but delivers a bit more voltage. ( and therefore fueling from IP). ok for a stock Patrol.
cheapest is from Amayama in Japon. comes in 10 days. 90 Euros. buy from their web site. you might need to pay taxes on arrival in your country.
it looks like MAF voltage vs quantity of air is quite different from earlier Di (4 pins) to CRD (5 pins). the 5pins has one more to accommodate a temp sensor, used by the CRD ÉCM but not by the Di ÉCM.
a 4 pins Nissan Maxima MAF may work on the Di but delivers a bit more voltage. ( and therefore fueling from IP). ok for a stock Patrol.
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3 Posts
Yes that was my intention. Unfortunately genuine MAFs start from 389 USD wich is crazy, no idea why early models are so expensive. Reference numbers are 22680AD200 and 22680AD201. If someone knows where I can find those at a reasonable price i would appreciate.
Mine shows the following stationary
1.95v > idle
2.7v at 2000 rpm
3.11v at 3000 rpm
3.17v at 4000 rpm.
So I think it goes out of spec above 3000 rpm.
Mine shows the following stationary
1.95v > idle
2.7v at 2000 rpm
3.11v at 3000 rpm
3.17v at 4000 rpm.
So I think it goes out of spec above 3000 rpm.
Easy
Direct from JAPON
AMAYAMA, the cheapest around you may find.
just google it and search for your MAF ref. around 100USD.
Your MAF values look very low to me.
small MAF value = small fueling from IP = little power.
Direct from JAPON
AMAYAMA, the cheapest around you may find.
just google it and search for your MAF ref. around 100USD.
Your MAF values look very low to me.
small MAF value = small fueling from IP = little power.
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