flyback direction for HIGH-Z injectors ????

[rossi46numberone]

Hi everybody,
I'm running high Z injectors for about one year without Ts diode.
I was wondering if working that way(without ts)can make some electric noise??
Can I get some improvement at idle for example?
Does this picture represent the right direction diode?
I'm asking because this allow the anode flow to the cathode,i'm a little bit confused.....
 
Can anybody explain to me with a little schematic or picture how do I have to wired it?
I planning to use a IN5402 diode ,is it good ?

It will be very helpfull,I don't want to kill ly ECU

Michele.

[rob@vems.co.uk]

You wont kill the ECU by getting the diode round the wrong way - you just wont get the advantage of the high voltage flyback.
Most people are using Transient suppresion diodes http://shop.vems.hu/catalog/throughole-diode-p-93.html

30V transient diode for high-voltage flyback for extremely fast injector closing (either inside controller case or in loom). Important: with high voltage flyback you MUST disable injector PWM (injpwm peak time=25.5msec, duty=100%) : prefer highZ injectors (so no series resistors needed). If you insist on lowZ injectors (under 5.2 Ohm), you will need to use series power resistors (usually 6.8 Ohm 50W see "output drivers" category). Unidir: striped-marked cathode towards the controller mainboard. Anode toward the injector common +12V. (the direction of the bidir does not matter so the bidir has no stripe. The unidir is said to work slightly better)."

http://uk.farnell.com/stmicroelectronics/1-5ke33a/diode-tvs-33v-1500w/dp/9801138

[mattias]

And you're certain that there isn't one already inside the ECU case?

[rossi46numberone]

Yes there is no TS diode.....

I also have in my spart component a 1.5KE30A(IN6282A)do you think it would be better than the IN5402 for my Siemens 630 cc High Z?
Do I have to wire it externaly to be able to test some different value ?
Is it 30v enough ?
I know that is a lot of questions but it's the first attempt and i don't want to do bad things....
I will post a picture of my board showing the way I have mounted the diode.

Michele

[rossi46numberone]

here is some pic's of my engine bay:




As you seen I use the EC18 unused pin 3 for flyback.
Do the diode in the right direction?

Michele

[jrussell]

That's the correct orientation for the flyback diode, but I can't figure out for the life of me why you wouldn't put it on the standard and well accepted ec36 pin 23 location. I predict that ECU is going to get fried if it's ever removed from that particular car.

[rossi46numberone]

Thanks for your reply.
In fact the 23 pin is already used as an output ground.
The board is internally grounded to make harness as light as possible...

Michele.

[Kamuto]

most important I think to cut that pin from board if you are using for flyback.

[rossi46numberone]

yes for sure that's the first thing I've done before soldering.....
Thanks for the interest

Does the flyback will help on little RPM oscillation at idle?

[boostd audi]

what all are you trying to run out of the ecu that your worried about harness size. 

i fit a plug and play into an mk4 and moutned ecu in the car and harness was pretty small i thought. was not drive by wire though.

is this not a dailly driven car?

[rossi46numberone]

In fact I kept the original ECU in place to control some stuff like :electronique throttle body,sterring switch,A/C switch,speedo-meter,etc...
I only use VEMS to control the Fuel and ignition.
Working that way I achieved to get the engine running like an OEM ( cold start,sterring rpm,A/C control rpm),and keep the OBD fonctionnal.
For me it's necessary because I use my car every days
And the most important for me is to keep the original ecu working in case of vems crash( by wrong manipulation ).
I'm still a newbie .
Talking about the harness why don't they use a different connector with a bigger ground pin section(mm²)  able to drive more current and work with only one wire ground input.
And that's what I've done on my board.
I run my car with Vems for more than one year now without flyback diode and it seems to be good.But I have some electric noise(bad craks) in my audio system that  and I can't fix.
and also some issue with my laptop connection.
Tha's why I would like to put this diode hoping for some improvement....