Cheap, simple, non-factory FI solution, parts, etc..., Type IV - This oughta be fun... |
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Cheap, simple, non-factory FI solution, parts, etc..., Type IV - This oughta be fun... |
Gint |
Jun 4 2009, 04:39 PM
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#1
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Mike Ginter Group: Admin Posts: 16,083 Joined: 26-December 02 From: Denver CO. Member No.: 20 Region Association: Rocky Mountains |
I've thought about doing a Megasquirt for a while now to replace my carbs. I have a Mallory that works great, so to keep the initial cost down as well as keep it simple, I want to do fuel only, but have an upgrade path available for ignition later. Ideally if this could be done for under $500 that would be fantastic.
So... What is the easiest, cheapest, most simple solution for induction parts? Throttle bodies, injectors, TPS, etc...? Which MS unit has the flexibility to do fuel now and ignotion later without starting all over again with a different ECU? Engine is a 2056 that is built on a 1.8 case and heads with a 2.0 crank, rods and P/Cs. Currently running dual Weber 40 IDFs. (IMG:style_emoticons/default/idea.gif) (my own note: 40 IDF 70 9A, Italy) |
mightyohm |
Jun 10 2009, 03:16 PM
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#2
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Advanced Member Group: Benefactors Posts: 2,277 Joined: 16-January 03 From: Seattle, WA Member No.: 162 Region Association: Pacific Northwest |
Mark summoned me so here's my $0.02!
As Mark and I found out, MICROsquirt was not made to accept a straight coil trigger signal on the tach input. We ran into a lot of problems with this, including actual physical damage of the Microsquirt due to the high voltage pulses that are present on the "low voltage" side of the coil (the primary). After messing with various resistors, capacitors, and other stuff for a week, we gave up, and that's why Mark is now an advocate of crankfire ignition. MEGAsquirt, on the other hand, supposedly can handle a tach signal directly. However, I don't recommend it for a couple reasons: 1. You are introducing a bunch of electrical noise to the Megasquirt by plumbing a very noisy ignition coil primary wire into the MS box. From reading the MS forums this can be problematic. 2. It is very clear that the MS community in general has moved away from direct coil triggering, probably because of #1. That isn't to say you can't make it work, just that you are going against the technical evolution of the MS FI system. It seems like everyone is using crankfire now. My Megasquirt setup, which has been running flawlessly for over 4 years now, uses a setup that avoids a lot of the problems with direct coil triggering, but without using crankfire. I added an MSD ignition to the car, and I trigger the Megasquirt off of the 12V tach output terminal on the MSD. The MSD tach output signal is very clean and free of a lot of the ignition noise you get by hooking directly to the coil. This allows me to get a good tach signal without resorting to crankfire. I am essentially using the MSD as a buffer for the tach signal, plus I get the benefits of CDI as a side benefit. You could probably use another brand or model CDI style ignition as long as it has a tach output pin like the MSD. That's not to say that we couldn't come up with a circuit that would be cheaper than the MSD and accomplish the same buffering effect, but in my case it was the easiest option since it uses off the shelf parts. Hope this helps... |
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