Toma

Is a 75mm MAF too big for 24 lb. injectors. Just got of the phone with a guy that builds motors -Tha Finnish Line Performance and he said that my car runs too rich because of that. My TB is the stock GT40- 65mm and my fuel pressure is always at 40 lbs. I thought it was the computer dumping a shitload of gas in there, due to the cam( E303), but he said it has nothing to do with the computer. Even a chip would not relieve it, only make it worse



That's it I'm tired of this crap, I'm going carbed!!!

catfish

Is the mass air calibrated for the 24's? You are running an E cam without a custom chip? You are leaving a lot of power on the table without some custom tuning. A good tuner can always work with larger than necessary injectors (well, within reason)

What brand mass air are you running? Is it a C&L? I had nothing but problems with mine. The car idled like crap. When I went with the turbo, I got a ProM 80mm. With the new chip, the idle problems went away.

Get a dyno session set up with Coastal. I spoke with them yesterday and they quoted $60 for three pulls with A/F measurement. Get that info, make a complete list of every mod done to the car, and call Johnson Motorsports in Mobile AL. Chris Johnson can take the dyno info and your set up and burn a custom chip that will solve your problems. The cost of the chip is about $340.

Toma

No that's why I called them, they were recommended as a Superchips vendor.

Toma

No, it's not calibrated and it's ProM. I called there to findout about Superchips and he said they were garbage. He said- " All they'll do is improve performance in an unmodified car. And it will make your car run even richer."

Damn mullets

catfish

I guess I should ask exactly what year Mustang you have. Is it a Cobra? What mods does it currently have? 24 lb injectors were standard on some Cobra models. Did you put the 24's on yourself? What about the E cam? What heads are you using?

Is the mass air calibrated for 19's?

Edit -

I know it's a lot of questions - but here is my reasoning: ( I apologize if this is info you already know)

Your MAS determines the injector duty cycle by measuring how much voltage is required to heat a coil in the intake tract to a known temp. At the ait flows over the element, more voltage is required to heat it. At any given voltage, your car's computer references a fuel table and sends a signal to the injector to open for a certain amount of time. If the mass air is set up for 19lb injectors, the computer cycles the injectors based on 19lbs of flow. So lets say themass air tells the computer that it is taking 1 volt (This is an example) to heat the element to it's set level. The computer goes to the table and finds that at 1 volt, the airflow entering the combustion chamber needs 2cc's of fuel. With the 19lb injectors, it takes .05 seconds (duty cycle) to release that much fuel. Well, with 24 lb injectors, you are getting 4cc's of fuel.

In a mass air calibrated for larger injectors, it creates an artificial environment to make the computer think less air is getting into the combustion chamber than really is.

The beauty of a custom chip is that a good programer can alter the actual fuel tables and make the computer work instead of tricking it into delivering the proper fuel.

catfish

Also, you want a custom chip, not an off the shelf chip. Like I stated above, with A/F ration info, JMS can burn a chip that will fix your problems. But you will need to resolve the mass air.

Toma

It's a '92 Coupe. The cam and injectors are aftermarket. The Mass air was already on the car when I bought it, so I do not know if it's been calibrated. The heads are GT40's, don't know which code Engine mods are MSD 6A (6AL going in soon) ,shorties, h-pipe, cold air, 75mm MAF, GT40 intake, GT40 heads, 24 lbs inj., and E303. Miscelleaneous other stuff like 3:55, subframes, aluminium driveshaft, etc.

catfish

Hell, a 92 coupe. You will never get it running right. They are junk. Sell it to me! (J/K)

I've never forgiven myself for selling my 93 coupe (I bought it new) I would love to have a 92/93 coupe.


Anyway, back to the problem. 24's are fine for that car. You can use every bit of the fuel they deliver. You either have a calibration problem in the mass air or are in need of a custom chip. What kind of timing are you running? Advancing the timing can help burn excess fuel as well.