Anyone knowledgeable on why the VG has 2 different MAF sensors? One has a 4 pin connection, the other has a 5 pin connection! Possibly hot film and hot wire? But the harness has 5 pins......

 

fwiw courtesyparts only shows 1 PN for all VG and VE 3rd gens

 

Yes all seem to have the same P/n but I'm not sure what the lower label 3 means

 

well if there's only one PN available from the OEM supplier then that can only mean that regardless of apparent physical differences, they are all identical in function.

 

Not sure why you are asking, but I have some thoughts.

I may be reaching too far back in my memory here, so help me out guys. I know that many junk yards indicate that the Infiniti J30 MAF is interchangeable. I remember looking at one and I know for a fact the plug is different (and different part # if I recall). I want to say that there was an extra pin at the end on the J30 MAF as well, but would have no function if wired into the Max.

So, are you talking with a J/Y that is telling you they are interchangeable? I've rewired a MAF on my car twice and I would not assume the hassle of wiring in a J30 plug into a Maxima just to have a J30 MAF. Assuming that's what is going on in your case.

 

absolutely no functional difference on them.

 

No "functional" difference.....agreed. Internally I recall they are the same. But the plug is different. Internet, do you recall if there is actually an extra pin on the J30? You got some in stock to compare (cosmetically...plug and pins)?

 

All the chassis harness plugs I found in the junkyard as well as mine
have 5 wires, but presently installed MAF has 4 pins!!! My alternate MAF sensor has 5 pins and I'll try it out to see how it runs and responds!

 

don't keep them in stock. a better comparison would be if someone could get the schematic for the 2 or even better the OE 5 pin vs the OE 4 pin sensor.

 

what models have a "4 pin" connector? I haven't taken the time to look at my 89, or 91 maximas, but my 91 FSM appears to have the same diagram for the MAF as the 94 VG.
94 VE has a 4-pin, but I am too lazy to trace wires in an e-foldout.

 

i was referring to internal schematic

 

ah... I can't seem to find one in the fsm... am i possibly missing it?

 

I'm going to go out on a limb and assume if there is an extra pin on certain 3rd gen MAF (simply never seen...nothing more), then it may be an extra ground point.
Having re-wired my MAF a couple of times, I remember specifically there is a ground sheild circling the MAF Harness wires its full length. Perhaps the 5 pin MAF connects to the other end of the ground shield wire?

But, I'm going to shut up until someone untangles this mystery. I'll do my part and check my FSM references for 1989 Max, 1993 Max, and 300zx.

 

having personal rewired this plug on my 91 Se i simply tapped in to the ground running the sensor and tied it to the ground running to the ignition and the response was nothing short of amazing by the way the five pin senor was on the 89 GXE models with the adjust suspen and I have an extra 5- pin sensor also. remeber they r calibrated to the flow rates of stock injectors.

 

No they are not - they are not "calibrated" at all (open the flow meter's brain box and you will find nothing in there to "tune" in order to effect "calibration"). Its simply a bunch of electronics that gets soldered together and that outputs a voltage signal proportional to the air mass flow rate through the tube. The choice of sensor and other components as well as the physical location of the sensor in the throat at the time of design and assembly simply define the response characteristics of the flow meter and the voltage signal it outputs.

The AFM knows nothing about injectors etc etc - it simply measures air mass flow rate accurately while compensating for density and temperature, and the ECU uses that signal (when in closed loop anyway) in combination with lots of other parameters to determine mixture requirements and therefore injector control.

 

The one I found the 5 pin MAF was possible out of the electronic suspension model! I'll call JWT and ask him tomorrow...but I think you're correct! I'm curious what that extra pin is for!!!! I've got some really good schematics but they don't show the internals of the MAF just relays and switches.

 

Here in South Africa we run A36 000 N61 MAFs (5 pin jobs). When I replaced mine with a US sourced A36 000 N60 unit (also 5 pin), I had a look in the brains of my original 5 pin unit and the 5th pin is connected to nothing on my original unit.

 

Makes sense. Good information. Never had a Max with the sonar suspension. Good to know all this talk and in the end, all this means nothing...as I think we all suspected! LOL!

Lvr: Although you are correct about specifically the 3rd gen Maxima MAF (an I think most/all newer MAF's) not being calibrated there are some older MAF's that are calibrated (maybe wrong "word" but bare with me). There was a write up I'll have to try and find, it was from the z31 forums if I recall. The write up showed how either on an early Infiniti J30 or z31 MAF (can't recall off hand) there is a specific place you can drill into the sensor box which exposes an adjustor ("potentiometer"?). This can be adjusted for tuning purposes and I recall the write up indicating this was an option instead of running the more costly z32 MAF.

I never pursued it because I ended up being able to run my stock Max MAF. But, out of curiousity....when starting my build YEARS ago, I did drill into my MAF....no adjuster. I hope I still have that write up...I'll link it.

 

Yeah - sure there will be MAFs that are "calibrated" via some pot or by eg mechanically cutting into a capacitor to change its value, but as you say the 3rd gen's are fixed at the time of production.

Sure would be interesting to see that writeup if you do bump into it - my guess is that the ability to "calibrate" any given MAF serves little to no purpose as long as the ultimate decision maker (ECU) bases its mixture control on the O2 during closed loop operation. Open loop may be a different story depending on how the ECU treats the TPS.

We here in South Africa are "blessed" with 3rd gen ECU designs running with no O2 .................. and if one could "calibrate" the MAF it sure would be a easy way to screw with the ECU's idea of a proper mixture

 

I will do my best to find my friend!

 

Found it on the z31 forums. The old link could not be found, however, what I have found does refer to exactly what I'm talking about. I would need more time to find information. But, I think from this point, anyone else on here can do the same as well.

http://z31.com/forum/viewtopic.php?t...maf+adjustment

http://z31.com/forum/viewtopic.php?t...fm+calibration

http://z31.com/forum/viewtopic.php?t...fm+calibration

Hope this helps you LvR. Sorry I couldn't find the images and write-up itself!

 

OK thanks, but looking at those links and also following a few other cross referenced, I get the distinct impression that the AFMs with "calibration" screws are actually the older "flapper" or vane type where the relative mechanical movement of a flap or vane in the air stream is transmitted to a potentiometer arm governed by a fixed rate spring (spring never getting stretched to a plastic state) to define the flow response, and on those kind of setups its rather easy to achieve simple mixture adjustment (in the absence of O2 only during closed loop) by simply changing the spring tension with a screw - iow you move the whole mapping system up a notch or 2 to the side you want.

What it all comes down to is that if you want proper throttle response and optimum fuel economy and drivability, its often best not to bugger around with engine mapping parameters governed by bits of electronics for which there are no detail response curves or circuit diagrams.

 

AMEN!

 

Yeah, I spoke to ben @ JWT and He stated that only 4 wires/pins are doing something and not to worry about the 5th pin....N60 are all the same 2 grounds, (1) 12v and (1) 5v reference to the ecu.....

 

Small correction - 2 ground wires, one +12V battery voltage and the varying flow signal wire going to the ECM - there is no 5V going to the MAF at all.

 

I never said anything about a 5 volt going to the MAF...I stated it as a 5V reference to the ecu (yes it varys and with airflow, density, humidity, altitude)....thanks for your $.01......

 

really then why do we have stand alone units tha do just that but way better than the factory electronics could have done?

 

Its not about the Mass Air Flow Sensor knowing the size of the injectors but rather simply the capacity or volume of air that sensor is physically cable of reading or reporting back to the ECU in order for it make adjustments in accordance to the density of the air measured. That being said thats why the Z32 MAF and injectors are such a good match to our engines. The injectors would provde fuel for way more airflow then what we'd see with our MAF (350WHP) and the Z32 (550WHP)!! Do u even know how they work?

 

If you want to pick an argument do it properly and stop arguing semantics. There also exist no "reference 5V" going to the ECU from the MAF - if the signal varies with airflow volume/mass then its no reference - by definition

 

Yep thats right - make stupid statements and then crap on me for posting facts ........................

Lets mess up the whole thread with people posting and defending crap arguments based on semantics then:

Did you or did you not make that statement numb-nuts? ............. and is that not exactly what I responded to ?................ so why go and change your story now and then pick a fight with me for correctly stating obvious facts?

Replacing our stock MAF and injectors with units able to measure bigger volumes and injecting bigger volumes will serve a purpose only if you intend running in open loop ECU mode and when you are trying to extract the maximum amount of power from the motor - as soon as your ECU goes closed loop your modification achieves little to nothing positive because the ECU will permanently be busy trying to negate the mismatch with pre-programmed maps you have just created - iow you will have poorer fuel consumption and your drivability will suffer in closed loop mode .................. but then I guess you obviously knew that eh?

The simple fact is that the std ECU expects a certain flow range associated to the varying voltage signal range that the MAF generates from its flow measurements - no matter what you do ito replacing the MAF, the ECU still interprets that incoming signal to to cover the same flow range even if you were to fit a blower and force double the air flow through a MAF pipe 1 foot in diameter - the MAF may be able to allow (at the same pressure differential across the MAF) and "measure" higher flow rates, but your std ECU couldn't give a damn about that - the ECU simply generates pulses of varying duration to feed the injectors in order to control mixture properties.

Your ability to fart around and replace arbitrarily choses components because of their potential and application in bigger motors, does not guarantee you eternal bliss unless your goal is to guarantee sub-optimum drivability and fuel economy.

I can but repeat what I said earlier "What it all comes down to is that if you want proper throttle response and optimum fuel economy and drivability, its often best not to bugger around with engine mapping parameters governed by bits of electronics for which there are no detail response curves or circuit diagrams" ....................... and unless you have detail response curves for the std and whatever other MAF you care to mention in order to compare properly and prove me wrong, I would suggest its actually you that don't know how these things work.

Ahem - because there are people out there that want the absolute best out of the beast and are prepared to spend both the time and money on such a venture - time and money the factory deemed unworthy because there is a limit to the amount of sensible tuning one can affect in a volume production environment? ..................... just my ignorant and uninformed guess but luckily you are sure to give me the real reason now eh?


How about we get back to the actual purpose of the thread then?

 

Cause it varies between 0-5volt depending on the air mass density,temperture, humiidity, etc and feeds that to the ecu...I'm not saying you're wrong, I'm just stating the samething you're saying in a different method....so chill...it's not a life or death situation...or is it?

 

I am in need of a MAF Sensor, bought 1 and has 4 pins and not 5 as the original.

Based on your comment here I am ok using it, but I will need to buy the connector also then.

Anyone sees a problem or would like to share an advise on what to pay attention to?

Thanks

 

Where did you get the MAF?
Regardless, I'll just say this, DO NOT bother with replacing the harness just to use this MAF you have. If it doesn't plug in, it's not for your car. Please go and buy the one for your car.

Try www.nissanpartsasap.com and CALL them. They are open Saturday till about noon. Good luck!

 

Couldn't have put it better myself.