Let's talk computers for a minute

[Stang_ROTY]

Capri306,

Thanks a lot for explaining that to a "rookie" like myself. I need all the help and advice I can get. First, let me say that almost every part I've bought has a EO or CARB # issued. This goes for the heads, EFI upper and lower, MSD distributor, headers & h-pipe, etc. the only thing that doesn't have an EO number is the bigger fuel rails I bought from Cartech to match the fuel system that came with the car and possibly the 30lb. injectors(which is an emissions issue). Virtually everything else Secondly,
Let me ask a question about the reference you made to "custom" chips. Superchips sent me a spec. sheet asking everything from my combustion ratio to injector size to my quarter mile times (which, of course..I don't have yet). Is this a "custom" chip they are going to program specifically for me (since I give them all the parameters that need be changed) and do you include Superchips in the category of "junk"????? And also, what would you do if you were in my shoes as far as modifying the CPU?

Thanks again for the help.

Originally posted by Capri306:
Stang_ROTY: what you're asking for is a completely customized electronic engine control computer. If you have all of the resources of Ford Motor Company at your disposal, by all means go for it. The computer Saleen offers appear to be the best so far, and they're the only ones making a totally aftermarket computer control box.

Getting back to reality, you're not fooling or tricking your computer into anything. Your stock MAF unit is calibrated to 19 pounders already. Substituting a 73mm calibrated for 30 pound injectors and installing 30 lb/hr injectors, as long as they are matched to the demands of the engine and to each other, will do the same job. The only thing the computer is doing is proportioning the weight of fuel to the weight of air entering the engine, and then making fine adjustments to that. The computer isn't fooled by any means, and it only interprets the signals it gets from sensors anyway. To modify the actual innards of an EEC-IV unit is a big no-no, as the chips are all soldered to the 'board.

When keen said the modded MAF lowers the output, he's right, it has to! 30 lb/hr is the MAXIMUM flow rate for those injectors. If you didn't trim the flow rate, especially at idle and cruising (95% of your driving conditions), you'd be blowing raw gasoline out the tailpipe. Think about the flow rating as WOT conditions only. The rest of the time, the computer is trying to keep your a/f ratio stoichiometric (14.7:1 by weight) and still carry out its functions to control emissions. When you go to WOT, the computer shuts down all emission control functions and goes into what I like to call "kick-azz mode". EGO signal is ignored, timing lookup tables shift, and so on.

On the emissions side, anything more than stock 19 pounders (other than a factory original Cobra Mustang setup with its factory 24 lb/hr system) is not going to pass emissions sinply because everything you add on to the engine control system (injectors, MAF, computer) has to be granted a CARB E.O. or have a 49-state certificate if you're not in Cali. In this case, a bigger MAF calibrated for 19 pounders (with an E.O.) and an adjustable fuel pressure regulator are your best options. A C4 transmission wouldn't cause the computer to throw a fit, it'd just act like an AOD in 3rd gear. I'm not sure what the legality issues are attached to this though. Guess you could tell them, "my tranny won't shift into overdrive." Hehehehe

On a final note, chips are absolutely the biggest waste of money and pieces of junk on the market today, and actually cause a loss of fuel economy, higher emissions (in most cases), and problems with driveability on the low or high end. Unless you can have one custom burned by someone with a full-blown dyno setup and the resouces to make sense of the info he gathers, steer clear of chips.