MoTeC Global Forum

I am not a mapper but have an (un) healthy interest in poking about in my Motec software. If the following scenario occurred what would be a fast way to diagnose what was the probable cause of the dead cylinder?

Car enters pits in a test environment. Driver complains of lack of power. Engine audibly not on all cylinders. Vital signs of oil pressure, and oil and water temperatures, all look healthy. The time to remove the rear bodywork to access the engine is lengthy. Someone connects a laptop to the *00 series ecu and opens ECU Manager to do some electronic diagnosis in the meantime.

What's the best and fastest procedure to electrically kill individual injectors or coils, assuming sequential injector firing, individual coil on plugs ignition? I have seen my mapper do this very quickly indeed and report, say, dead ignition activity cylinder 5 in firing order, physical cylinder X.

Thanks, I would like to add this knowledge to my "diagnostic toolbox".

Go into Adjust, Fuel/Ignition, Individual Cylinder trims. and then trim each cylinder separately by -99
If this kills another cylinder that cylinder is working, if it makes no difference you know this is the cylinder that is not running.

Thanks IDP, I have had a quick look in ECU Manager and whilst I understand why -99% would kill an injector's fuel spray, I am unsure how the ignition timing trim would work. my set up has ignition in degrees, so what would occur setting one cylinder's ignition in degrees to -99? Would it not still try to fire, albeit at the wrong time?

Yes, for sure it will still try to fire but, only if it is firing anyway.

So if -99 makes an audible difference to engine note the engine is firing on that cylinder.

Cutting fuel would be the best option though.

Altering timing like that, especially if it's a wasted spark setup might cause other issues as there will also be a spark firing elsewhere.

And really you'd probably only need to fire say 50-60deg earlier or later than normal to make it a non event for that cylinder.

Best using fuel only though.