MAF Question

Kiljosh · **MAF Question**

When I was talking to rpm getting my cam spec I asked about my injectors and if I'd be ok with the 14's. He said I was right on the edge so it wouldnt hurt to pick up a set of 19's for cheap.

Well I recently picked up a set of 19lb injectors for a measly 30 bucks off of ebay. They are off of a 93 GT I believe and was told by my uncle that they should fit in my car. If I want to install these I need a MAS calibrated for 19#'ers right?

Can I pickup a stock one and have it fit on my car(not worried about splicing, im not scared of wires) or will I need to find a new one for my year and have it calibrated.

Reason being I just lost my job and I'm running low on funds for my install, dont really have 300 to drop on mass air. I still need a new timing cover, power steering pump pulley, plugs, fluids, AC recharge, tune, Corey's powdercoating(

), and some bolts need replacing.

slvr2000stang · 06-30-2005, 07:50 AM

There is no "Calibrated MAF"

You need to have a chip or flash that sets the injector values in the EEC correctly.

Even if you were to put on a different MAF the transfer function in the EEC would have to be changed.

97Stallion · 06-30-2005, 10:29 AM


Quote: Originally Posted by Kiljosh When I was talking to rpm getting my cam spec I asked about my injectors and if I'd be ok with the 14's. He said I was right on the edge so it wouldnt hurt to pick up a set of 19's for cheap. Well I recently picked up a set of 19lb injectors for a measly 30 bucks off of ebay. They are off of a 93 GT I believe and was told by my uncle that they should fit in my car. If I want to install these I need a MAS calibrated for 19#'ers right? Can I pickup a stock one and have it fit on my car(not worried about splicing, im not scared of wires) or will I need to find a new one for my year and have it calibrated. Reason being I just lost my job and I'm running low on funds for my install, dont really have 300 to drop on mass air. I still need a new timing cover, power steering pump pulley, plugs, fluids, AC recharge, tune, Corey's powdercoating( ), and some bolts need replacing.

what are you cam spec? lift, duration, lobe seperation??? And what else major do you have done? What is your estimated hp that you THINK you'll be making?

Kiljosh · 06-30-2005, 04:33 PM

Mik told me to maybe expect 160 to 180, he specced me a pretty aggressive cam, 216/216 with 1.8 RR so I can get full potential from the .545 springs.

Full exhaust, shorty headers, ported upper/lower, BV Heads, that cam, sct chip, cai, UDP, 3.73, and jmodded tranny. Others too but I am in a hurry.

Im going to get my chip reflashed when I'm done, maybe even get a new SCT progger so Justin can work on the shift points through email with me. Think he can change it through the chip. I don't see why not.

And silverstang, what aboput the C&L meters I saw in 50resto. You can get a new sample tube for them to work with diff injectors.

Kiljosh · 07-02-2005, 07:30 PM

OK so just to be sure, I can use my stock MAF as long as I get the values changed in my computer when I reburn my chip right?

**SpectorV** · 07-02-2005, 07:35 PM

I would assume a maf from any year mustang that ran 19s would work... but I dont think gt mafs work on v6s (at least the 99 ups) and they have 19s for some years... hmmmm im sure someone will jump in here in a min and tell ya.

You may can just get a 99 up maf from a v6 for dirt cheap.

Kiljosh · 07-02-2005, 07:37 PM

"You may can just get a 99 up maf from a v6 for dirt cheap."

Thats what I'm hoping for cause I see no reason for a aftermarket MAF, especially since they are like 300 bucks.

**SpectorV** · 07-02-2005, 07:44 PM

clean those 19s up with some desiel fuel good (i belive you can use that... hmm)

Ponycarman · 07-02-2005, 11:16 PM

What's a MAF measure?

AIRFLOW

Changing out the MAF will do nothing for accounting for the injector flow. Like it's been said you have to reprogram the computer to properly pulse the injectors. Unless you are flowing more air than the MAF can properly read then you do not need a new MAF.

Steve

tedness · 07-02-2005, 11:27 PM

mmmm xcalibrator 2....orgasmic.

damn my engine was dirty...

Kiljosh · 07-02-2005, 11:40 PM


Quote: Originally Posted by Ponycarman What's a MAF measure? AIRFLOW Changing out the MAF will do nothing for accounting for the injector flow. Like it's been said you have to reprogram the computer to properly pulse the injectors. Unless you are flowing more air than the MAF can properly read then you do not need a new MAF. Steve

Thank you, I understand now. I always thought a MAF measured airflow and told the computer how much fuel to give the engine, thus changing injector size would fuck everything up. But I believe that the o2 sensors handle fuel delivery right?

Ponycarman · 07-03-2005, 11:04 AM

A little story on how EFI woks.

The computer controls the fuel. Nothing else does. How the computer decides what amount of fuel to inject is based on readings from many sensors. They are, in our Mustangs (other years/cars/brands may be and are different):

MAF - which measures the amount of air going into the engine.

TPS - throttle position sensor, measures how much foot you got into the engine.

ECT - engine coolant temperature sensor, tells the puter how hot the coolant is.

IAT - intake air temperature sensor, tells the puter how hot the incoming air is.

O2 - how rich/lean the exhaust is

Crank position sensor/ cam position sensor - tells the computer where the pistons are. So it know when to fire the injectors and plugs.

Knock sensor - tells the puter when it's knocking.

Speed and distance sensor - tells the puter how fast you are going (in the trans).

Now how the puter uses all this stuff is somewhat complicated but it's simple to explain and understand the basics of. The computer has tables that are programmed by the tuner, either Ford, the aftermarket or you. It'll have a basic table it refers to that tells it if the engine is warmed up (ECT) and at idle then inject X amount of fuel.

From that point, X amount of fuel, it gets modified based on sensor input. Increase the throttle (TPS) and the computer adds more fuel, how much is based on the load. Load is determined by air in (MAF) and throttle position.

IAT is used to determine density of the air, in conjunction with the MAF input. Hotter air is less dense at the same velocity so you need to compensate in the amount of fuel. Hotter air is also more detonation prone.

ECT tells the computer how hot the engine is, cold engines need a richer mix.

Fine tuning of the amount of fuel is based on O2 sensor input, this is a feedback to the computer.

All of those sensor adjustments to the initial fuel supplied are all specified by the tuner.

So, the MAF merely tells the computer "hey this much air is going into the engine". The computer looks at that, the RPM, the TPS, and all the other sensors and says we need this much fuel, based on the assumption you have the injectors it expects to have. Add 19 lb/hr injectors in place of the 14 lb/hr injectors the computer thinks is there and you will be injection more fuel per pulse than the computer expects. The O2 sensors will see this as rich and teh computer may be able to adjust somewhat. But it'll probably throiw a code and go into limp home mode, which is not what you want.

Limp home mode is essentially when the computer sees something it doesn't expect, like sensor readings that are way off and it doesn;t trust them. So it defaults to a program that is designed to get the car home or to a shop without added problems, so it's usually richer than optimal and the timing is backed off. It'll get you engine home safely, but it isn't optimal by a long shot.

Steve

WhiteStang99 · 07-03-2005, 12:14 PM

^Great information.