Type of RPM signal from a smallport 4a

**Cuzzo** · 17-02-2006, 05:41 PM

What type of rpm signal does the igniter(is it?) produce?

Is it a hall effect, Variable, or something else?
Thanx heaps,
Adam
(rep will be in it for ya all)

**ViPeR_NiPPleX** · 17-02-2006, 05:56 PM

uhhh... ignitors are usually triggered by a signal rather than producing one... however assuming its transistor based, you would say it would output a squarewave.... yeerrrr

**timbosaurus** · 17-02-2006, 06:09 PM

Originally Posted by cuzzo

What type of rpm signal does the igniter(is it?) produce?

Is it a hall effect, Variable, or something else?
Thanx heaps,
Adam
(rep will be in it for ya all)

There's a sensor in or on ur distributor/cam/crank that produces ur timing pulse. That sensor can be a hall effect, reluctor etc.

To put it simply it is that signal that is sent to a transistor based ignition module (of which an ignitor is one form) which amplifies the current and sends it to the coil. On newer cars (i say newer as mine is nearly 30 years old

) that signal is routed through the engine management system for (amongst many other things) advancing/retarding THEN sent to the ignitor to drive the coils.

So i guess it depends on which signal you mean?

I dont know 4a's at all, but someone might be able to let you know what type of sensor you have, and whether it is routed through an EMS. The signal coming from the ignitor is the same for most cars though... A 3-20ms pulse which finishes when the engine is expected to spark!

I know this isn't entirely accurate, like i said, a simplification.

Choice,
T.

**ViPeR_NiPPleX** · 17-02-2006, 06:14 PM

4ages typically have variable reluctance type CAS. there is the VAST and EDIS(??) types. Both have two wheels, one of them has a 1-4 type, the other a 4-24?? top of my head... check www.autoshop101.com for more info.

**Cuzzo** · 18-02-2006, 08:09 AM

So is the RPM signal an impulse one.(Into a ae82 if that makes a difference)

**gearb0x** · 18-02-2006, 03:21 PM

are you looking for a trigger for your tacho? Small ports use a Dizzy and single coil so you can trigger off the negative of the coil

Smallports use 2 toothed wheels in the dizzy, one a 24 tooth, and 1 single tooth which has 2 sensors on it. They are variable reluctance and go to the ECU, which then triggers the ignitor.