Xavier Delcour

Been fighting this issue for the last month and after another day of troubleshooting I'm starting to be frustrated. Hopefully I can be redirected to some good lecture on how CAM and Crank sync works on a BP4W engine or some working scopes with a 36-2 wheel

My track trash-can car it's a 99 nb 1.8 JDM model fair basic. The car it's basically stock on the engine part with a Kakimoto exhaust and home made intake (so far I have dedicated my mods mainly on reliability with coolant reroute, crossflow radiator, xidas suspension, poly bushing and new brakes).

The car has a Motorsport Electronic ECU 442 as I'm preparing the car to get some power upgrades as soon as the driver is not the limiting factor anymore(have a kraken kit sitting at home waiting for winter to start). I did install at the same time a 36-2 trigger wheel and a new fuel pump. The car been working quite well so far and was quite happy trying to improve my times on the local circuits.

Last month suddenly one morning it decided not to start any more while I didn't do any recent change to it. After some troubleshooting and playing with the scope mode I could find that both CAM and Crank weren't being able to sync. I reverted to the original trigger wheel and there surprises the car is able to start.

I checked timing and seems when I set it to - 10 of advance it's alright. When I look at the captures below, I do see that it seems the 34 edge is not on the same rising time as the cam (seems a slight delay on the cam).

I sadly don't have any capture on the scope with the 36-2 when it was working to compare (lessons learned....)

Here a couple of captures with the original and 36-2 trigger wheel and a zip with the scope logs.


Working original trigger wheel.


Not working 36-2 Trigger wheel

Hopefully someone can help me. Thanks

emilio700

iTrader: (3)

OEM NA/NB cam/crank sensor is not a hall, so raw waveform is sinusoidal. ECU filtering converts to a simulated square wave. Old Megasquirt and even OEM had a problem filtering that signal when it degrades with heat. Does your ECU allow you to log raw voltage/wave? Does it provide tools for tuning filters?

Xavier Delcour

Thanks Emilio, been checking today and while the ecu allows to save the raw data for analog inputs it seems the cam and crank trigger aren't part of them. ECU has some filter options (none, low and high). I did try the three of them with the same results.

Is there any documentation on the 36-2 trigger wheel which shows which teeth the cam and crank should be together?