Syvecs Forums

I am not a mapper but have an (un) healthy interest in poking about in ecu 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 ecu and opens the Syvecs software 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".

I assume individual cylinder trims would achieve this, but can you trim say 99% of an individual cylinder's fuelling, and how would one safely trim timing or otherwise kill a spark?

Fueling for Cylinder could be done instantly on the fly by just changing the Cylinder Trim Multiplier from 1.000 to 0

Ignition im not sure if setting the dwell time to 0ms would do it but the way to do it properly would be to monitor the coil flyback voltages (Not TTL so would have to be on S8) then you will be able to see which cylinder is lacking compression due to the voltage difference. Obviously more compression the harder the coil has to work!

Thinking more of dead coil or wiring issue than no compression. Can you try the zero coil dwell on some Guinea pig please Ryan? Thanks for the reply.

fuel cylinder trim as Ryan suggests works well..

ie. number 3 makes no difference if I switch it off... therefore cylinder 3 has the issue

Thanks JGM

If you want to use the cylinder trims, you will need to adjust the cylinder trim TPS threshold to be less than the idle TPS, whereas by default it's 100%. Easy to miss and I know I've missed it once or twice.

pavlo wrote:If you want to use the cylinder trims, you will need to adjust the cylinder trim TPS threshold to be less than the idle TPS, whereas by default it's 100%. Easy to miss and I know I've missed it once or twice.

OK, right, noted, thanks for the warning!