All Maf'd Out...

[Rezlo]

So after my S14 RB25 maxing out a Q45 then Z32 i eventualy swapped the pfc to a R33 GTR D-jetro PFC,, that solved my problem,,,

My S13 has a MAF PFC as well and was maxing the Q45 at 1.3bar with the GT35... so i tried something a little different before ditching that for a D-jetro.

100mm intake with hacked Q45...

64mm center tube the sensor sits in to prevent turbulance that plauges these things

Finnished... well almost, still needs to be polished and to epoxy the sensor into place...

Now at 1.6bar im only at 4.6volts, should be able to get to my boost target now by 5volts, even better than this is that there is no usual part throttle surge or voltage movement which usualy happens.

Just a cheap upgrade option for those guys maxing MAF's

[Adriano]

And you dont have to use a Q45 sensor, just do the sums, and any nissan AFM sensor can be used, just need to get the pipe size right to suit. Mine is a stock gtr sensor in a 4.75in internal diameter pipe, should be 5v at 500rwkw

[The Dan]

I don't see how the sensor can now accurately measure correct airflow? You are only measuring one small part of it.

[heller44]

Think about how a hot wire air flow meter works, it is only measuring the air going past the element itself, which is just a portion of the total airflow. This would just make it a different percentage, may not be perfectly linear response but should be able to be mapped against.

[VB-]

I don't see how the sensor can now accurately measure correct airflow? You are only measuring one small part of it.

just change the load scale to suit. as long as the flow through the AFM is CONSISTANT in its ratio with the air going around, there will be no problem. which, unless there is turbulance through the pipe, wont be a problem.

now, that internal pipe may protect against, or make the problem worse (only my opinion). very interested to see results.

[Rezlo]

And you dont have to use a Q45 sensor, just do the sums, and any nissan AFM sensor can be used, just need to get the pipe size right to suit. Mine is a stock gtr sensor in a 4.75in internal diameter pipe, should be 5v at 500rwkw

Just so happens i have about 10 Q45's laying around from cars ive changed to D-jetro.

It works perfectly, I have done it without a center pipe before and it always picked up a cruize hesitation and usualy a .2 to .3v movement @80 - 120kph in the afm voltage from the air hitting the filter (which you can realy feel in an SR20), i now have thin, clean and smooth line when I use the oscilloscope. The center tube runs the length of the lower outer section, which means i have roughly 100mm of tube before and after the sensor itself to help the air smooth out slightly to stop turbo and air filter interference.

All i did to get it going nice was to rescale the AFM (over 35% at higher flow rates), still need to do a full tune obviously to see full benefit due to the added boost I can now run.

Edited August 31, 2008 by Rezlo

[STATUS]

yeah its a good trick, i usually go a ford lightning afm if i run out of scope but if the customer is happy with a quick fix it does wrk.. not perfect but fairly damn good.