The maf sensor signal varies from 0 to 5v and from what I read is exponential in relation to the actual Air Flow. Does anyone have specific information on the MAF Voltage vs. Air Flow relation?

I plan on logging data using my UTEC to ultimately calculate the VE vs. RPM.

 

Any ideas where I might be able to find this information?

 

I think most people go the MAP route if they're trying circumvent the MAF...

 

Supply voltage Battery voltage (11 - 14)V

Output voltage at idle 1.1 - 1.5*V

Mass air flow (Using CONSULT-II or GST) 2.0 - 6.0 g.m/sec at idle*

7.0 - 20.0 g.m/sec at 2,500 rpm*

*: Engine is warmed up to normal operating temperature and running under no-load.

Also use this as reference/conversion table. Hope that helps.
http://www.stealth316.com/2-air-fuel-flow.htm

 

A mass air flow sensor is basicly a thermal measuring device. It has a pin or heated grid that air flows over. The computer measures how much voltage is required to keep that grid at a certain temperature. More air flowing over the grid more current is generated.

 

Unfortunately the device creates an exponential [nonlinear] voltage vs flow curve.

The equation is roughly X raised to the 2.5-2.7 power. Which means you must accurately measure using a flow bench to define the offset constant.

Important to use oem duct fore and aft as standing waves [at different rpms] can create errors.

Someone must bite the bullet and pay for an accurate flow vs voltage test using at least 3-5 to average out the errors [accuracy may only be 3-5%]

http://www.geocities.com/tech4tdi/pages/maf.html

 

Thank you for the helpful information Q45tech.

 

At WOT the ecu uses a excessively rich A/F to protect cats from melting and to cool combustion chamber [to not overload cooling system and work with low quality premium US pump gasoline] so MAF voltage accuracy may be immaterial unless it is so inaccurate as to LEAN the A/F too much and melt things.

The WOT at HP peak may be 10.5 A/F so whether 10.0AF or 11.025 A/F [+-5%] isn't very important unless you are trying to squeeze out every HP at the expense of durability [cats, exhaust valve seals]

The important thing is to measure the air flow restriction.....[a Q45 MAF creates a 6"-7" WC [H2O] or <1/4 psi restriction at redline] I would expect the same or a little less on a 3.5 MAF

 

I believe running rich causes catalytic converters to heat up actually. So while it does run rich at WOT, this has nothing to do with the cats...

To the OP: you may get the data you want by contacting the folks at UpRev (the developers of the Cipher).

 

Measure the EGT with varing A/F you'll see how cool it gets richer than 12:1.

The cats cannot convert anything without oxygen

 

Actually reduction of nitrogen oxides to nitrogen and oxygen will produce oxygen - and is one of the three reactions that occur in modern catalytic converters. The oxygen produced can be utilized for the other two reactions.

And again, pretty sure I don't need to test this as it's well established that running rich will heat up, and potentially destroy a converter. Here's a quick google link with reference and quote from http://www.catalyticconverter.org/care/index.htm:

The exhaust gas temperature may decrease due to the cooling effects of excess fuel vapor, but this pre-cat temperature reduction is misleading, and the subsequent chemical reactions in the cat downstream may well destroy them from overheating...

 

So is it possible that running 12-14psi with a vortech will send to much voltage to the MAF and harm it?

 

Yes. We have new Modified Nissan MAF sensors to allow keeping stock ECU and wiring while supporting up to 600hp. Please contact us via e-mail. We should have pricing on Monday/Tuesday for this part.

 

What injectors are you guys using in with the greddy kit?