# 60-2 wheel, VR sensor and bosch 139 on megasquirt 2



## iZOTOPE (Jul 2, 2006)

Done some changes to my board recently, i've switched from hall input to VR input (preparing the car for distributorless and wasted spark with bosch ignition modules), installed a 3 wire VR sensor from a vr6 engine, and tried to start the car, the logs show a clean signal and i get spark, but it pops out in the exhaust. 

VRIN is jumpered to TACHSELECT, VROUT is jumpered to TSEL, and i have a 1k pull-up resistor from TACHSELECT to +5v on proto area, and the two pots are set fully CCW. 

Also did some measurements on the sensor: between pin 1 and pin 3 there is continuity, between pin 1 and pin 2 i get ~900 ohm, between pin 2 and pin 3 i get ~900ohm, so pin 2 is the signal and the other two are grounds/shield . 

i'm a little confused about the settings in megatune: 

spark mode: toothed wheel 
skip pulses: 3 
ignition input capture: rising edge 
spark output: going high(inverted) (it was going low(normal) when i used the hall input) - i'm not sure about this one if i set it up correctly, the ms2 sends a signal to the bosch 139 igniter who fires the coil. 

trigger wheel settings: 

single wheel with missing tooth 
trigger wheel teeth: 60 
missing teeth: 2 
tooth #1 : 78 (deg BTDC) - VW wheel from AGG motor 2.0 8v (ABA equivalent). 
wheel speed: crank wheel


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## Prof315 (Jan 5, 2009)

pin 1 should be VR - pin2 VR + and pin 3 shield ( needs to be grounded on the block) 

since you are not direct firing the coil I would leave the spark output going low that part shouldn't change with the switch to VR


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## iZOTOPE (Jul 2, 2006)

thanks very much prof315! 

i'll do the changes in megatune and try again to start the car  

one question that is on my mind, on msextra.com forums i've posted about wasted spark using bosch 139 modules, what i'm asking if it is possible to fire 2 modules from sparkA and 2 modules from sparkB, i know that i must do the ground switching circuits from d14 and d16 to drive the igniters. 


thanks again!


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## need_a_VR6 (May 19, 1999)

Also I never use a pullup on the input circuit using that sensor. I think I use VROUTINV with falling edge, so your settings and jumpers should be fine there. 

All ignition modules I've tried can run off the LED circuit with a 1k pullup, and you should have no problem firing multiple units from one output transistor. Make sure you're set to NON INVERTED as well!


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## iZOTOPE (Jul 2, 2006)

ok, i'll set the input capture to rising edge and output to : going low (normal) and go from there, with hall sensor the car runs and idles like a charm hope it will come back to life with vr sensor as well. 

i've put the 1k pull-up on TACHSELECT because if i want to switch back to hall sensor i only move some jumpers and load the proper msq file  (the resistor was there in the first place  ) 

then go to junkyard and pick some igniters and some old school coils  

also as i've read in the manual trigger angle is not used if input is from a toothed wheel. 

thanks guys ! 
:beer::beer::beer::beer::beer::beer:


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## iZOTOPE (Jul 2, 2006)

car started after i removed the pull-up resistor from +5v to tachselect and after i wired the vr sensor as prof315 told me, the idle was screwed a little but nothing to worry, reved the car a little bit and no sync losses and no miss fires. 

the input capture is set to rising edge, and spark output is set to going low(normal) 

also with toohed wheel selected the middle led option was grayed out, and the led doesn't do anything, if i revert to hall sensor the led works as expected, indicating when spark occurs. 
is this normal or did i screwed up something when i played with the resistor? 

10x to all 
:beer:


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## need_a_VR6 (May 19, 1999)

If you want the middle led to do something you have to set it up using the output port settings... where it is in the menus depends on your code version. Just enable it and set up the parameters to something that you can easily vary (rpm, tps, etc) and see if you can get it to light up again. I don't know why it was doing something in distro mode as the ctr led is usually set up for warmup indication.


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## iZOTOPE (Jul 2, 2006)

in trigger return mode it lights up if spark occures and on more ignition settings i can set the middle led to off or ignition trigger indicator, in toothed wheel mode the middle led indicator option is grayed out, i'm using 3.1.0 firmware, also in 2.1.0p same thing happened. 
probably that is how it is programmed, when i switch my ignition to on all the three led blink once so there is no problem in the led circuit.


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## need_a_VR6 (May 19, 1999)

In wheel mode your probably just locked in to using the ctr led for a gpo and not an indicator.


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