4AGE Distributor VR sensor compability

[CHB]

guys, i have problems with installing Megasquirt MS2 V3 in one of my mate's AE86. it has big port 4AGE and i get the RPM signal from the distributor 4 tooth VR sensor and fetch it to a electronics Ignitor from 4K engine. so basically it is as such

4 tooth VR sensor ->Electronic Ignitor(to convert AC signal from VR sensor into square wave) -> MS2 V3

this methods works very well on my previous ride on the same MS2 V3. now i just reconnect it exactly the same way into this 4AGE. it does fired up but immediately dies off. checked with every wires connection and absolutely no problem with wiring. i did managed to fired up and run it into very high RPM and i need to keep my foot on the throttle. it will immediately dies of if i put away my foot from the throttle.

now my question is, does VR sensor in a 4AGE compatible with electronics ignitor from 4K engine?

[knightrous]

I've no information on the 4K ignitor, but the standard VAST type ignitor on the AW11 AFM bigport works without an ecu signal. You can start the car and fuel it with a can of start ya bastard and it will run (although it will be locked at 10' of timing). If you can test this, you will soon know if you have spark/ignitor problems or something else.

To my understanding, all VR sensors are the same, they all provide the zero crossing point for the MS to consider a pulse.

[CHB]

yeah i'll try to give that a go and see if it will fire up with "Fuel only" setup.
thanks for your tips.

[knightrous]

yeah i'll try to give that a go and see if it will fire up with "Fuel only" setup.
thanks for your tips.

Save yourself the hassle of changin the MS2 settings/firmware, buy a can of start ya bastard/aero start, unplug the injectors and crank the motor over while spraying the SYB/aero start and it will fire

[metcap]

one question, why do you use a 4k ignitor? I've ran 4age setup before with the 4 point vr sensor feeding into the ms2 and firing a coil using the vb921 no problems.

[Grega]

correct. a 4AGE will run without the computer hooked up - (IIRC bill sherwood did this a million years ago) of course no advance etc will be there.

[CHB]

finally the 4AGE started with "Fuel only" MS2, ignition is controlled by the 4K ignitor running 12* BTDC locked out timing. now i really can see the problem.
the engine is idling smoothly at 800RPM. BUT my MS2 is detecting twice the RPM ~ 1600-1700 RPM.. why is it so? i swap the whole MS2 with wiring from my 3T-C into this 4AGE and running the same RPM pick up (Using 4 tooth via 4K ignitor to square up the pulses) and now it is detecting twice the RPM that the engine actually running.
any one have came across the same problem?

[metcap]

if you need to *square up the pulses* then you must be doing something wrong coz youre doing what the ms2 is suppose to do. And to run fuel only when youve the capability to have full control over spark is a sore waste.The 4age I did idles rock steady at 900rpm and revs hard in excess of 9k rpms no problems.

[knightrous]

The VAST igniters filter the VR sensors pickups into a simple square wave signal that you can connect to the MS2 as a hall/opto input. It's 'suppose' to be simpler to setup and more reliable then the VR sensors which normally need tuned/trimmed to get them to read correctly across the whole rev range.

I basically want to use the VAST igniter because it's the standard unit in my AW11 and I will be able to use the stock wiring and be able to switch back to the standard ECU without any wiring changes.

[CHB]

i am using "Igf" wire to feed the RPM signal from the toyota ignitor into the MS2 and the MS2 send signal to the negative side of the ignition coil thru "IGT" wire. that is how i connect it previously but since i still cannot start the car with MS2 takes control of the ignition, so i disconnect the "Igt" and let the toyota ignitor do the job. do you guys have any idea that why the RPM signal can be double up?

[knightrous]

You should be using the NE signal for RPM. The IGF is just a confirmation signal from the igniter to tell the ECU that the spark was actually fired, it also confirms that the igniter is working (Throws up an error light if it doesn't).

[gearb0x]

I would double check the setup of the MS3 to make sure its not expecting a VR signal it self (the V3 board can be setup for square wave like the Ne signal or direct input from the VR sensor)

[CHB]

btw, the Ne signal is produced according to the 4 tooth or the 24 tooth? the ignitor i am using now is not from VAST ignition. all it does is fire the coil when ever a tooth is passed thru the VR sensor. anyway, i will try to swap the signal fetch to the MS2 by using Ne wire instead of Igf wire and see how things goes.

[gearb0x]

IT will work with either wheel, but i would use the 4 tooth for your purposes

As far as i know, since the IGF is a confirmation signal that the spark fired, it will actually move around in relation to your advance with regards to what degree of rotation it fires. The NE signal will always be what you set the static timing too

[gearb0x]

oh! I just remembered. the 4age dizzy with a 24 tooth wheel has 2 pickups on the single toothed wheel! what you are getting is a signal every 180 degrees hence the double the rpm

EDIT: haha scratch that, you said its 24/4 tooth, I dont have any experience with them not sure how many pickups they have

[Grega]

....shouldn't you be triggering on IGT?

http://www.autoshop101.com/forms/h39.pdf

gearb0x - doesn't it depend on the 4AGE dizzy. the earlys were the 24 / 4 and the laters (ae92) were 24 /1

both will have two pickups - : more http://www.autoshop101.com/forms/h23.pdf

[knightrous]

btw, the Ne signal is produced according to the 4 tooth or the 24 tooth? the ignitor i am using now is not from VAST ignition. all it does is fire the coil when ever a tooth is passed thru the VR sensor. anyway, i will try to swap the signal fetch to the MS2 by using Ne wire instead of Igf wire and see how things goes.

Depends on the 4AGE. The AFM Bigport 4AGE should have 4 teeth on the NE wheel and 1 tooth on the G+ wheel. The Smallport & 20V's should have 24 teeth on the NE wheel and 4 teeth on the G+ wheel (I could be wrong about this last bit)

[metcap]

i am using "Igf" wire to feed the RPM signal from the toyota ignitor into the MS2 and the MS2 send signal to the negative side of the ignition coil thru "IGT" wire. that is how i connect it previously but since i still cannot start the car with MS2 takes control of the ignition, so i disconnect the "Igt" and let the toyota ignitor do the job.

trace the 2 wires from the 4 point vr sensor and feed in into the ms2 vr circuit and use the vb921/bip to fire the ignition coil, you dun need to make use of another external ignitor to control ignition. If you need a working msq I've a copy I can share but you'd need to fine tune for your application.

[CHB]

guys.. i managed to get the car started with both fuel and ignition control today.. which means there is nothing wrong with the wiring/connection. but i still feels like the RPM is not quite there.. the original digital RPM on the dash is dead so i'll connect a external RPM meter and see if it match the RPM in the megatune or not. when i check the ignition timing using a timing gun, i hardly notice there is extra spark event due to the double RPM.