more pictures:

schematic of the stock wiring

I have installed a genboard v3.2 in my car by modifying the motronic m2.8 ECU.

m2.8 has a 55pin connector.

It has:


Camtrig(Hall type) and Crank(Vr)

4injectors(running fully sequencial)

1dual WS coil with external ignitionmodule. the module want 5v to trig and the stock dwell at idle is 7ms.


pulseair(fuel ventilation)

Q: how to configure the output to pulseair??

Main relay and Fuel relay

PWM idle valve


I have connected all sensors and actuators from the stock connector to the genboard.

Besides the stock sensors my plans are to use egt, wbo2 and boostcontroller.

The first start attempt went really well. And the engine idles really nice. But when I tried to rev up the engine it looses sync around 3000rpm(and the Wxx parameter on the lcd starts to count up rapidly).

My first thought was that c30 was to big.

-But the schematic says 1nF and MembersPage/EmilLarsson confirms that the value is correct for multitooth setup.

I have soldered SJ6 and i have left SJ3 unsoldered

So I then checked doublechecked all components around the lm1815 and everything is correct.

Next test was to test the circuit with a functiongenerator, and it works perfectly all the way up to (atleast)10000hz with a signal amplitude of 60mv up to (atleast)10v

I have checked the RC-circuits around pin 7 and 14. and the waveforms seems correct.

So I tried to short one of the 10kohm resistors. The effect of this was that the "new" threshold before the engine starts to loose sync is 1500rpm.

So my conclution is that the problems must be because of noise. Which is strange because the sensor is connected with ground connected to JP6, signal to JP7 and the shield is connected to GND(not gnd5). One problem might be of the wiring, the schematic indicates that there is a shield on the wiring, but I don't know for sure.

I think the 1nf cap connected to pin 3 will not be to good of supressing noise when the voltage is higher, since the lm1815 will limit the voltage on pin3 to +-0.5v. so the noise might charge the peak detector cap at pin 7.

I will try to put a 10nf in place of d14 to see if that helps.

this will result 1600ohm impendance at 10000rpm. should not be to bad since of the higher output voltage at high rpm. And the phase error can not be more than 1.5deg.

I have also measured the dc resistance of the sensor and it is 630ohm. And when cranking I get an output voltage of about 0.2V ac rms.(measured with a DVM).

Q: Is there anyone else having similar problems?

A: I have the exakt problem, check my history [My page]

I dont know what to do. Changing wheel from 60-2 to 36-1 is left to try but i don´t think that is the problem.

Q: Have you tried to look at the signal with a scope?

A: (From Samuel) No, but i have recorded the signal into my audioprogram. [When it cuts]

I have not solderd any filters, maybe that helps but i´m new to electronics so I don´t know much, and i´m not much help either. But maybe whe can solve it together.

I think it´s something with the missing tooth, thats why i will try another triggerwheel with another type of missing tooth. What type of wheel do you use? Picture? (He is using the stock motronic trigger wheel, hopefully this is another problem than Samuel's //Emil)



I found the problem, check the graph.

description and solution at:


I will upload schematics and some pictures.

I have also added support for the extra main relay. I connected the Key to a free input(scl) to add support for a "turbo timer" so that the engine is allowed to run for a while after the ignition is turned off.

Q: Is there any documentation of what all the parameters are in LCD_MENU_MMM? By just looking at the code is not so obvious!

A: Check the bottom of the page there is a link pointing to the refcard (as the name says, a reference card for menu textual commands) - DB

A: Yes, I have found the refcard, but the refcard doesn't show what all parameters that are shown on the lcd are.

Q: And why does not mxo and mxp work?

I first tried with the latest CVS, but with that version the genboard resets whenever I get input from the triggers.

So now I use 2004-11-24. Later a saw that the newest versions are to instable to use. but a better varning would have saved me from a lot of extra work.

Could you please upload your config.txt and tables.txt and link them here?

Could someone comment on the parts related to:

-dwell, Dwell looks a bit high, Might be a problem/bug related to the dwell getting close to ignition firing, Try to lower the dwell to 3ms or something just to check.. Also try moving the trigger back a bit by modifying the trigger_tooth setting (of course, raise tdcdelay.

I measured the dwell time with the stock ECU connected and it is 7ms on idle. -- This can be correct, but the coil will work at lower dwell settings too, check this just to see if there is a bug related to this.. //Emil

-knock, I have found a datasheet for the c20let and it says that the stock ecu only looks for knock at 15khz. But all configs I have seen are looking at knock around 5-8khz. BTW, how wide is the bandpass center frequency?

-ve learn with nbo2


I am in need for bigger injectors. currently I am using injectors from 850 t5 approx: 340cc/min at 4.5bar.

I would need atleast 500cc/min, since I plan on using ethanol e85. If someone know of a good source I, or has a couple of injectors for sale, then please write here!

Did you tune your engine? I have c20let in opel kadet D with vems 3.1. It started nice and I am just starting to tune it. Maybe you can let me have your tables.txt file for my starting point. Did you find right knock frequency for this engine? -MembersPage/TonciLoncar