Having a few problems with setting up the engine at idle sub 1500 and 2500 to 3000 rpm for SVA. have a busa engine in an MNR vortex with a car exhaust and a car type intake system (all runners equal length and no air box). Fitted a cat exhaust and startered a fire nearly due to misfire in the cylinders. Hooked up an Horiba Mexa 5 gas analyser to each exhaust pipe and measured the cylinder emissions with the throttle balanced and found cyl 3 and 1 to be running so lean they where not firing (20% o2 and zero CO, 1500 PPM hexane C6 equivalent) Cylinders 4 and 2 running at 10 % CO and at 7 % CO% respectively.

high performance engines have poor idle combustion stability due to low air motion (tumble and swirl) and as such suffer from freqent misfire if not rich enough. In my engine the air flow is balanced, the injectors have been flowed and checked but the rich AFR cylinders follow the injector lead (if i move the injector lead from 4 to 3 the lean AFR follows the move) so its the lead. measure the resistance of all wires to injectors, all 0.2 ohm and 11.8 v being supplied to all 4 injectors.

Have put a scope on it and the pulses are all very similar.

am running 4 in to 1 MNR exhaust

Added power commander and adjusted the individual cylinder by +55% on cylinder 3 and +25% on cylinder 1, - 15 on cyl 4 and 2. Engine runs great but on opening throttle to go to 2500 rpm , misfire again.

anyone seen this also ? any cures suggestion of issues with loom which is a suzuki loom spliced to am MNR loom ?

No direct experience of BEC but you want around 14 volts arriving at each of the injectors. Nice plan to give them each their own ignition live supply rather than have them share. 11.8 is very poor. Voltage across the battery terminals with the engine running should be the same 14v ish.

[Hi thanks for the advice, i will actually run 4 wires from the +ve battery[ to each injector as they are switched by the earth and will see what happens. Ran the car tonight and on the oscilliscope the injector voltage was 6.2 volt max, that could be a response thing rather than a supply think , not big on electrics so not sure]Originally posted by Dusty
No direct experience of BEC but you want around 14 volts arriving at each of the injectors. Nice plan to give them each their own ignition live supply rather than have them share. 11.8 is very poor. Voltage across the battery terminals with the engine running should be the same 14v ish.