I am going to install Vems on Renault 4cyl, 16v engine.

Engine is F4R730, Clio RS 172, year 2000.

MembersPage/Cerozg/Trigger - trigger related subpage

Collect some info (specific engine code, year, ...)

V3.8b (oid11249 v3/11837) has arrived.


I have some doubts about flyback, sck pullup on V3.8b board and main supply.


Can you help me and define which solution is applied when V3.8b is purchased as preassembled with 30V flyback?

I have found two solutions. I am not sure which is right.

1. Only 1K5E30V diode from flyback pad to ec36/pin23.

2. 1K5E30V diode + capacitor (light red one wima mks 4 4.7 uF 100 - 10% which comes with recue kit, probably noise filter but i am not sure) between flyback pad and ground

That is correct:


Is ground reinforcement essential or optional?

Optional. v3.8 has 54um (copper thickness) so unless the IGBT-s or the injectors are stressed to the extreme (>16A simultaneous), the onboard traces suffice without added wires. Good harness is needed in any case.

About SCK pullup on ISP header. Is it optional or essential on V3.8b board? It didnt came soldered on board.

SCK has no effect if the v3 starts up (always on powerup) and communicates. Without SCK pullup (and 47uF or bigger electrolyte capacitor on 5V) it might happen that (say) once in 20 startups it goes into "ISP" mode (not normal running).

Can you check the bottom of the ISP pinheader ? On v3.8b the diagonal resistor not needed, 4k7 near the pinheader. Try to measure with a 100k pulldown resistor applied temporarily to SCK, SCK voltage should be >4V.

Is main supply on V3.8b preassembled? Diode and PTC fuse were soldered on board. It seems nothing else is needed.

Should be preassembled, yes.

OK. Thanks.

Transient suppressor 1k5 / 18V

Between GND and EC36/pin23: it is NOT BY399 but a transient suppressor



Engine bay is too hazardous-very hot and possible leaks from cooling system, moisture... Ventilation bay is populated with battery, air filter, ventilation fan and lots of moisture. The most convenient place i found is under the front passenger seat. But wires will be 3 meters long in one direction!!! Will this be a problem-voltage drop, noise...?

Should be good under the front passenger seat.

I managed to place ecu closer, so wires are about 2 meters long.