DIY_EFI Digest V1 #246

[talltom]

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>
>From: "John Faubion" <jfaubion at beaches.net>
>Date: Sun, 25 Aug 1996 10:43:03 -0500
>Subject: Re: EFI musings
>
>> -> Well Dave with some prudent shopping you could have done it cheaper
>> -> too. I picked up a GM #730 ECM, harness and most of the sensors from
>> ...
>> -> especially if you can adapt factory parts. Ford and GM already spent
>> -> the money to make them reliable, why not use them?
>> 
>>  What do you intend to do about reprogramming the ECM?
>>                                                                          
>                                            
>Actually very little. The programming for the '90-'92 F-bodies is a speed
>density system. By sizing the injectors correctly you can adjust for the
>size difference between the engines. For example, the factory 5.7L used a
>Lucas #5207011 injector that flows 20.73 lb./hr at 44 psi of fuel pressure.
>My 427 is 427/350 = 1.22 or 22% larger. If I maintain the same RPM range of
>idle-5000 RPM that the factory used, then I would need to use an injector
>that flows 22% more fuel to maintain the same injector pulse width. So my
>injectors need to be 20.73 x 1.22 = 25.29 lb./hr. in this case I could use
>the injectors from a Nissan 300ZX (Lucas #5206004) and adjust the fuel
>pressure. These flow 24.73 lb./hr at 37psi. To get 25.29 lb./hr I need to
>use 25.29/24.73 = 1.02 x 37 = 37.84 psi of fuel pressure. By sizing the
>injectors this way and maintaining the same injector pulse width, the ECM
>fuel maps should be close. With the learning ability built into this ECM,
>it should be able to compensate for the small variances. 
>
>If you are using a V8 that had the same type injection you want to use,
>(i.e. your going to TPI and running a 350 small block) then your
>programming is easy. Even if you have modified the engine with aftermarket
>pieces such as a cam, headers, better heads etc., just contact someone that
>already programs PROMs for these. Get information from them about their
>chips on a version that would be close to what you have already built. If
>like me you are building something the factory never even considered like
>port EFI on a 427 big block, this could still be an option. You only need a
>chip that will support the gear ratios, rear axle ratio, approximent
>weight, type of injection (TPI, MPI, TBI) and most importantly RPM range.
>Since I will probably not maintain the same RPM range (my 427 is built for
>1500-6500 RPM) I would need a stage 3 or 4 chip from Hypertech. This will
>also require an increase in the size of my injectors to support the
>horsepower level of this engine. Even if I buy an aftermarket chip, I'll
>still be under $400 for my total project.
>
>The factory systems are much easier to adapt than to build your own
>controller. I like to idea of building my own but I just don't have the
>money to sink into the project. I'm also trying to decode the factory ROM
>as well. I have access to the hardware to do this but as I'm sure everyone
>knows, this is not a simple undertaking. Until then though, there are
>several options open.
>
>John Faubion
>jfaubion at beaches.net
>

Well that's all fine but what does this system do when MP>29.9"?
   You all can say I'm halucinating, but I say something that looks like it
would really have some potential. It was an electro-mechanical gadget that
sensed MAP and regulated fuel supply pressure as a derivative of MAP. Now
if we could come up with a good o2 sensor reasonable this thing could 
provide enrichment as a function of MAP and o2 sensor that would allow
one to use stock injectors on artificially insemenated engs.(oops, I meant
aspirated.) Seemed cheap, easy, programable, and most importantly universal.
With this the programing of the ecu wouldn't play much of a role, would have
the limp mode, and be monopoly proof!