HI.
Any one know how, using weber marelli L6/L8 ecu, how to run a distributor less
ignition, i know you add another amp but not quite sure how to
wire it in to the loom and ecu, and are any ecu modifications needed.

 

you will need to run P8 if your gonna use just the ecu to run DIS , theres a mod in the chip , speak to kenny at MSD numbers below !!

 

THANKS.

 

you do not need to run a P8 ecu at all. that may be the easiest way, but it's certainly not the only way, or probably the cheaper way.

all you need is another amp (or replace the single one with a twin) to run in wasted spark mode (i.e. 2 plugs get a spark at the same time, but only one cylinder is ready for firing). you then need some way for the pulse from the ecu to the original amp to be split into 2 and sent to the correct amp for firing of the right pair of cylinders. this can be done with a microcontroller sensing the pulses from both the crank position sensor ad the phase sensor, but they need somesignal conditioning first.

 

And after all that you then need to then get an output back to how it was to drive the rev counter again...

Its not simple chaps

However, im quite hopefull that these will do what we all want them to do:
https://passionford.com/forum/viewtopic.php?t=95706

 

ok so you can still tell me you dont need P8 to run coilpack on weber -

i didnt think so , all youve done is list a possibility what a crock , if its that easy why dont you build the unit your on a bout and sell it ?



like i said m8 to run it with no probs you will need the coil pack adapter that stu is trying to sort ( would be good if it happens _ havnt read the post yet ) but it can be done with P8 with just a chip mod and a bit of wiring and another amp ( or a dual amp) . the only problem you will have using P8 is driving the rev counter as stu says

i know all this because we ( me and MSD) looked into all the possibilities last year , and found that the best most reliable was to use the factory system !!

 

i was just saying that there are other ways to do it rather than changing ecu. just because you don't fully understand them, doesn't mean they aren't as good. you even say on the other post that 'this is one of the best conversions you can do with your car"

to some people (e.g. Simon SECS and others) they're not that difficult to design and build. i could do it myself and sell them, but really can't be arsed. especially as there is already such a thing on the market that doesn't cost much so there's not enough profit in it for me to invest in the necessary equipment to make them professionally.

it's really not difficult, it's just logic and electronics. and it's not even expensive if you already have all of the gear to program microcontrollers. an external one is slightly more difficult than an internal to the ecu one, as the signals will need conditioning that's already done in the ecu.

 

bit like this

 

exactly like that rich. a microcontroller and a few components on a bit of breadboard is not rocket science is it?

 

not rocket science Nick, no, but a tad more tricky than may first appear, to deal with all eventualities.. the "easy" way of rerouting the 2 ignition signals also has the limitation of coil on-time of the standard distributor setup. Extending the coil on-time to take full advantage of the DIS coilpack is a bit more involved..
An interesting point is, if you trace out the circuit, there is unused component positions on L8 that correspond to a second amplifier drive output.. .. work continues

 

This reminds me of a chat we never got round to Rich.. i must update you at some point as to what is happening!

 

OK Stu, yeah please do.. I kinda assumed that you were sorted...

 

Drop me a PM with your number and a time i can call you as ive bloody lost it pal

 

what are you saying is the "easy" rich?

I would do it by utilising the fact that the phase sensor has 2 pulses per revolution of the distributor shaft at 90 degrees apart, and the crankshaft has 4. from that, you know which pair to fire. am i missing something and oversimplifying it?

the other development sounds interesting. did none of the other marelli equipped factory cars use dizzyless (anything from the fiat group?)

 

that is it in a nutshell Nick, and just split up the original amplifier trigger signal pulse train into 2 alternating signals, obviously synchronised with the phase sensor.
This does mean that there is a limited coil on-time at high rpm (same limitation as the standard system has) - yes it will drive 2 amplifers and a distributorless coilpack, but part of the benefit of DIS ignition (ie large spark energy independent of rpm) is not realised.
There are some sideline issues to deal with regarding synchronisation at startup, since you don't know what position you are starting from. The logical way is to wait until you see a full cycle of signals to establish where you are, but that could mean 2 full revolutions of cranking before the engine starts... there are a number of points in the cycle where you can infer the engine position earlier, but it does add complication.
Increasing coil dwell adds more complication, as you can only do that by pre-empting the coil turn onpoint, the turn-off point cannot be moved as that determines the firing point ignition timing. It becomes rpm dependent and no longer can be treated as a straight logic function.

I suspect that some application or other incorporated DIS ignition drive, like I said before, the L8 pcb has unpopulated components positions corresponding to a secong ignition drive channel, but it comes from a processor port line which obviously needs to be driven by the main program to be any use.. I have'nt been able to find another application using L8 and DIS yet.. Any Lancia Integrale versions DIS?

 

i didnt want to discuss your work rich on the bb, we did discuss this little mod on my car before we decided to use the factory setup , but due to the limitations mentioned by rich above was the reason we didnt 'just' use this mod

easier and less complicated or even cost effective - ? - nah didnt think so , if it was I would have done it !!




godd work rich m8 , keep it up !!

 

good work rich

easier and less complicated - probably not, but maybe challenging and interesting to some people.

cost effective - to some people yes, a microcontroller and a few components and some time costs far less than a P8 ecu.

i can understand your decision based on reliability given your vehicle use though

 

 

Clever chap is our Rich

 

HI ALL,

I've started something hereTOPIC, i had seen RICH'S website and saw his way
of using a l8 to go dizzy less, but thoght there may be another way.

Regards Dave R.

 

Jesus You techno whizzkids give me a headache !
I just bought P8 and was done with it , rev counter fires off one amp , job done . What an improvement over a dizzy too , much better , no fluffing through the rev range , solid pull up to redline , wish i'd done it earlier .
Cheers

 

i'll second all that !!