Megasquirt question.

[90TurboVan]

That won't work. It almost works in 8-2, but the missing pulses would be at the wrong places. Didn't really think that through, I guess. PM sent, Jeremy.

[UnaClocker]

I think if you were to give the signal information of both distributor signals to James & Ken in the MSExtra forums, they could very easily make the MS2 support it and fire a coilpack. Might even be able to do it with just the HEP output that catches the window.

[rfb6435]

Has anyone played around with decoding the turbo HEP in megasuirt similar to how they do the Neon and NGC crank triggers yet?

I am thinking Megasquirt now and would have to pickup a TBI distributor if this isn't done.

-Rich

[UnaClocker]

You don't have to use a TBI distributor. The turbo has two HEP's. One of them is the funky signal for the turbo computer, the other is the same signal that the TBI engine sees. You simply have to figure out which is which.

[rfb6435]

Quote:

Originally Posted by UnaClocker You don't have to use a TBI distributor. The turbo has two HEP's. One of them is the funky signal for the turbo computer, the other is the same signal that the TBI engine sees. You simply have to figure out which is which.

The turbo HEPs will work on the TBI but the shutter flap has a window in it on the turbo distributor. This makes the signal different for turbo models. From what I have read it is not compatible with Megasquirt without a special decoder. If we had the turbo HEP decoder that would be great since it would be an improvement over the TBI signal.

I think that the turbo distributor just uses the double HEP in order to get a more precise timing measurement. It can use the window and the second HEP to have a much more accurate timing window than the TBI distributor can. There are pictures of the Turbo HEP outputs in the electronic distributor adapter thread.

I am not sure how much it matters though since our cars don't have a high RPM power band anyway but there must have been a reason that they added the extra output and decoding since it wouldn't have been cheap.

-Rich

[90TurboVan]

Turbo HEP outputs.

TBI output is just a square wave, doesn't have the "missing" part of the teeth like the turbo outputs do. The ECU uses that to determine which cylinder is going to be at TDC in order to fire the injectors in the right order/bank. You can use a TBI distributor with MS as long as you don't want to fire two coilpacks in wasted spark or do COP, MS doesn't fire its banks of injectors with any respect to what cylinder is at TDC. It only helps idle quality/low load emissions anyway.

Wouldn't be hard to get MSnS-e or MS-II to decode the turbo HEP's, someone just has to write the code.

[UnaClocker]

You don't even have to write the code with MS2Extra, you just have to give them the angles of what happens when, and put them into the lookup table in the code. MS2E uses a "generic" wheel decoder that makes it easy to add new wheels.
Guess I had read some misinformation about how the pickup in the turbo distributor works. Seems like I had read that one HEP picked up the window, and the other was mounted higher so it missed the window. Now I see that info was wrong. Thanks.