[DSG04GT]

What's the size of a 2004 GT stock MAF?

[SWEET2KSTANG]

85mm

[DSG04GT]

Ah thank you, couldn't find it anywhere lol.

[SWEET2KSTANG]

no problem

[04GTAMPA]

I'm sorry, I thought it was 80mm....

[SWEET2KSTANG]

chnged to 85mm in 01

[2000stangGT]

^^ the man is a fonce of endless mustang related information

[BumbleBeeStang04]

No it is still 80mm in 04 it just flows better than the 99-01 80mm MAF

[04GTAMPA]

^^^ that is correct. It is still 80mm... they changed the air sensor position....

[SWEET2KSTANG]

my bad, i was thinking about the 02-04 aftermarket 85mm. i guess i just had my head up my ass.

[04GTAMPA]

or your ass deep in your head? LOL it's good bud!

[SWEET2KSTANG]

hey hey, lets not get to technical. either way, neither my ass or my head was in its correct spot. still going to chiroprator over that!

[CobraR]

is it worth it to upgrade the MAF? and what size would be recommended

[SWEET2KSTANG]

i went with a c&l and i can not say enough about it! car responded great to it, pulled harder through the rpm range all the way to the limiter, looks good, and i highly recommend it! you also have to pay the price for it too, most people wont want to.

[04BorlaBee]

if i do the C&L MAF, how long can i run without changing the tune? it has a dyno tune right now with the stock MAF, will it mess it up upgrading to the C&L 85 mm?

[I8ACMRO]

I still like the 90mm Lightning MAF. Don't have one yet (no need) but Ford Racing Parts and Accessories at great prices has it for like $79

[tbirdscwd]

You need to change the tune if you switch the MAF to anything else but stock. During WOT and open loop conditions, the computer adds fuel based on the MAF transfer rate which tells the computer how much air is actually ingested by the engine based on the 0-5v reading given by the MAF. If the MAF is changed and tune isn't adjusted to compensate, the transfer rate will be off and the computer will add fuel according to the old settings and throw your A/F ratio way off.

The 03-04 also have the IAT sensor integrated into the MAF instead of having a seperate one like previous models.

LMAFs also don't have the integrated IAT

[04BorlaBee]

Originally Posted by tbirdscwd You need to change the tune if you switch the MAF to anything else but stock. During WOT and open loop conditions, the computer adds fuel based on the MAF transfer rate which tells the computer how much air is actually ingested by the engine based on the 0-5v reading given by the MAF. If the MAF is changed and tune isn't adjusted to compensate, the transfer rate will be off and the computer will add fuel according to the old settings and throw your A/F ratio way off. The 03-04 also have the IAT sensor integrated into the MAF instead of having a seperate one like previous models. LMAFs also don't have the integrated IAT

I will have to run it for maybe a week or two with the dyno tune for the 80mm instead of the 85mm, until I can get up to the dyno. As long as I dont run it hard I should be ok right ? Maybe just running rich?

[tbirdscwd]

Originally Posted by 04BorlaBee I will have to run it for maybe a week or two with the dyno tune for the 80mm instead of the 85mm, until I can get up to the dyno. As long as I dont run it hard I should be ok right ? Maybe just running rich?

You will actually run lean. Basically the MAFs on our cars work by electricity heating a wire the sensor. As air passes through the housing, it cools the wire. The PCM must then push more current through the wire to keep the temperature of the wire constant. The more air going through the housing, the more current is required to keep the wire at a constant temp. The circuit is only a 5v circuit which is why you can "peg" the MAF by introducing it to more airflow than 5v can compensate for and bring the wire back to temp. The bigger the housing, them more air is actually entering the engine per volt read by the MAF. That is why you increase the size of the MAF on higher HP applications......

so a MAF reading 3v on a 85mm MAF will actually translate into a lot more air intake than 3v reading from a 80mm MAF. If the tune isn't changed, your engine will be taking in a lot more air than it "thinks" it is and won't add sufficient fuel.

Long, long story short, as long as you don't go into open loop or by wide open throttle, the oxygen sensors will detect it going lean and tell the computer to add more fuel. The problem is that under WOT the oxygen sensors are basically bypasses and the fuel goes strictly off the preset tables in the tune.