Megajolt spark cut using afr oupt to prevent damage to engine?
Turbo Mini Forums

Just a thought that popped into my head whilst walking home from work, is there a possibility that you can use the output from the wideband controller 0-5v to trigger something on the megajolt unit that will cut the spark/retard timing etc when the engine starts running lean? Just thinking it could be a useful safety feature I could add to Shauna's mini whilst I'm in the wiring phase of things, if that's even possible? The megajolt unit is a v3.
Cheers.

possible but youll need to code the ecu to do it conditionally, i.e. lean on cruise/over-run is desirable but you dont want it spark cutting then, best do it with a pressure threshold. also engines will occationally missfire or do an incomplete burn this could trigger your safety thing needlessly.

I am assuming ofcourse Bowling &Grippo still let you play with the code. i have in my head the code may be closed/semi closed source these days.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

K.I.S.S.

They don't die, they just get faster!

Yeah, it would be nice if something like this could possibly be a built in feature using the map and the afr input, then as you say it would only do it conditionally. Just a passing thought i had on the walk home haha.

doesnt mjlj have the facility to pull timing based on a temperature input?
i know i have modified a few to use the 0-5v input and i know john uses this to datalog afr on mjlj,

im thinking you could setup an afr v timing map

im trying to install the software to edit a map for a friend but having trouble on this laptop

you could always set up an external circuit using a voltage comparator to cut the coil power when it goes past a certain afr ( the same way the mjlj hard cut works)
but the problem i can see straight away with this with out including a tps or maybe map signal it will cause the coils to cut on over run, it will probably cut the coil on a hard gear change and the SU leans slightly as you open the throttle quickly, it may cut in there too

Yes i moved to the darkside

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just had another look over this, now i have my mapping laptop out it looks like this could be fairly easy to achieve

you can use the 0-5v analog input to data log the afrs i know ive done this on johns and bennys
BUT the outputs can also be triggered by this 0-5 input, so there is nothing stopping you from setting up one of the 4 outputs up to go +ve under a lean condition exactly when can be tweeked in the software
this output can be connected into the hardcut module, it looks like this activates ( cuts spark ) on a +ve signal
a couple diodes bit of wire and 10 mins soldering cold sort this

edit, however i still think this would cause issues when on over run and just in general as Denis suggests

edit 2 you could use 2 outputs, one based on map one based on afr and some logic chips but i guess Tom has this one covered
how far do you want to go to use an electronic fail safe to correct a mechanical problem
( no substitute for a properly setup needle and carb )_

Edited by Brett on 15th Sep, 2014.

Yes i moved to the darkside

Instagram @jdm_brett