I've read that the only way to advance the timing on our Daks was through the Crank position sensor. The little black thing that fits in the bellhousing and mounts to the block. I'm curious if anyone knows of a product that can adjust the values it puts out to advance the timing. I know of the mod where you remove material to lower/rise it from its resting position to advance it a few degrees. I'm looking to build a circuit that delays the signal for a period of time, and even adjust to the engine speed. If I can get this off the groud, I would love to sell them. If anyone is interested, I could use a few testers as well.

 

Heh.

Suggestion: Do what the turbo 4bangers do; replace the PROM in the SBEC with a EEPROM, copy all the software from the old one into the new one, and tune the SBEC.

My main problem with doing that right now is the lack of a proper definition table and ASM file for a V6 or V8; but I'm fairly certain they're out there somewhere.

Or upgrade to the wiring harness and ECU out of a 1996 (which will be a bit fun; that may also take swapping to a 42RE/44RE transmission, because that's also done that same model year!) where it's just a standard OBDII tuning procedure (Flyin' Ryan has V6 tunes also, it turns out).

Since you really want to do more than just shift the initial timing point on MPFI or SEFI to make the best use of the ECU doing the timing advance, truly.

RwP

 

That would certainly work, but I'm not equipped for that kinda stuff, at least not yet. This is more of a proof of concept.

 

For that, I'm not sure in and out would do; you'd really want to adjust it before/after the current position, it seems to me.

RwP

 

By Lower/Rise I meant relative to the plate, the only advancement mod calls for material to be ground away for the sensor to see the 'holes' early and advance the timing. This 'chip' I want to make will remove the need to grind away from your bellhousing by just delaying the signal to the pcm, creating the same final result.
Here's a writeup for the mod

 

The first message in that thread says what I said - move it relative to the rotational position; in this case, nearer the oil filter (which would advance the timing).

It also does it for the entire range.

Your thought of "delaying" the signal would make the timing delayed; you need to ADVANCE the signal, before the current sensor sees it. Not sure how to do that in a simple chip.

RwP

 

As Ralph noted, trying to advance timing with circuitry (or software) would require "anticipating" the next leading edge pulse from the flywheel, not sure how you would do that. I would approach this by including a modified mount for the crank position sensor that puts it way advanced, then adjust delay from there. I wonder how far you have to move the sensor physically to get a single degree of advance? Given the diameter of the flywheel I would guess its pretty far, like maybe half an inch.

Ralph, have you looked at the Megasquirt for controlling a V8? Its been a while, but its all open source, and I remember seeing files that people had developed for 5.2 and 5.9 engines.

 

Well, the length of an arc is Deg * Radius * Pi / 180

So, 1 Deg and a flywheel radius of 3.88 inches, would give .06768 inches or a little more than 1/16 of an inch. A half inch would give you close to 8 degrees of advance.

 

The Megasquirt is one choice, yes.

I'd rather keep it all original as much as possible *grins* Just a'hankerin' to tune something, and dasn't dare do SWMBO's Cougar until I have a proven record (it's why teh truck will be self-painted first; if I do good, I get to do her car. If I screw up, someone else does her car. I'm not sure which one is the better choice .... *grins* )

RwP

 

I came up with a little less than 7.5 degrees for half an inch, using a quick calculation of the flywheel circumference and dividing that into 360. So either way a significant change is needed in the mounting position of the crank sensor to get a good start point on the "advance" side I'd say.