MAP Info Needed

[pontiacgp]

My GP seems to be running great but I want to know why it is and if I have it set up correctly. With the Fast EFI it has a MAP sensor on the body of the unit. The MSD AL6-2 also has a MAP sensor. I have been reading about what MAP sensors do but I can't find info relating to my set up. I'm curious about the vacuum advance that I can factor in with the ignition box. With the MAP on the fuel injection adjusting the fuel according to what the engine needs does the ignition box upset the EFI's function with adjusting the vacuum advance according to the engine's needs. I read that vacuum advance is more critical to a carburated engine but they are comparing that to an engine with an ECU controlling the timing and fuel. I can sorta get my head around each system but I would like to know how each system affects the other so I can tweak each system if necessary so they play nice with each other...

thanks for any help but please do not confuse me by using big words...

 

[Turbo Zach]

Does your EFI unit have veritable timing capabilities? If so why would you need such a fancy ignition box? The MAP sensor in the ignition box is more for boost retard setups. I don't really understand what your problem is?

 

[64nailhead]

I have to admit that I'm not really as familiar with Fast EFI as I am with other system (MS and Holley), but you have a 2 dimensional table correct? Assuming ye, then tune your timing the same way you would as if you had a dizzy with base timing, springs (mechanical advance) and vacuum canister for vacuum advance. Manifold absolute pressure is a number that is easily converted to inches of HG.

If you have two systems running the same motor, then you have to tune each separately. But each follows the same concepts as if it were on a carb and dizzy.

Maybe I missed something in your question though. The joy of EFI systems is the tuning in a moments notice via a change in a 2D table rather than pulling your dizzy to limit mechanical advance or changing jets in your carb.

 

[pontiacgp]

Does your EFI unit have veritable timing capabilities? If so why would you need such a fancy ignition box? The MAP sensor in the ignition box is more for boost retard setups. I don't really understand what your problem is?

The EFI system does not affect the timing. The ignition box sets up the run curves and the vacuum advance curve. What I am curious is the MAP in the EFI controls the fuel and tjhe MAP in the ignition box control the vacuum advance. Under part load conditions the engine requires less fuel and that would be controlled by the EFI. What I want to make sure I'm not confusing the EFI system under part load with the vacuum advance settings.

 

[pontiacgp]

I have to admit that I'm not really as familiar with Fast EFI as I am with other system (MS and Holley), but you have a 2 dimensional table correct? Assuming ye, then tune your timing the same way you would as if you had a dizzy with base timing, springs (mechanical advance) and vacuum canister for vacuum advance. Manifold absolute pressure is a number that is easily converted to inches of HG.

If you have two systems running the same motor, then you have to tune each separately. But each follows the same concepts as if it were on a carb and dizzy.

Maybe I missed something in your question though. The joy of EFI systems is the tuning in a moments notice via a change in a 2D table rather than pulling your dizzy to limit mechanical advance or changing jets in your carb.

I have each system tuned but once in a while I like to over think things... ...

 

[fleming442]

supercalifragilisticexpiailidocious. b*tch!

So, the Fast EFI doesn't have the 2 pin plug for the 6AL_2? Even FI Tech has that! Here's my take on it: The MSD is basically a "dumb" system. Yes, you can program the curve based on vacuum, BUT it doesn't see other things that the EFI does like TPS, AFR, intake air and coolant temp. I would rather have the EFI run the ignition, than 2 separate systems.

 

[pontiacgp]

calling my MSD dumb......

 

[fleming442]

Yours is smarter than mine; it's digital and programmable. I'm still rockin' the analog.

 

[pontiacgp]

One of the things I liked about the Fast is that I could use any distributor with it, the MSD box I have came as an after thought, the price of the box wouldn't let me walk away empty handed...

 

[fleming442]

What model of the FAST EFI do you have? Which distributor?