Miss-fire below 3000rpm at light load

[mackei23b]

Hi there

Well my last real challenge is to get rid of a miss-fire below 3000rpm.

So far I've changed the injectors, plugs, ignition leads and coil to rule these out, but the miss-fire remains. After 3000rpm the engine runs clean and pulls like a train....! The miss-fire is only at light load, as soon as I open the throttle the miss-fire clears, though it does not stay below 3000rpm for long....I've played about with the fueling and ignition curves and it has not cured it.

The engine is a ford 2l duratec running on jenvey 45mm throttle bodies and a dead head fuel rail (I'm thinking about changing the fuel rail to a more conventional one with an inlet and outlet) in my Caterham. I've attached the data log (in the zip file, as suggested, thank you) with has some reasonably consistent running below 3000rpm and the msq file as well . The voltage is lower than I'd expect as I'm seeing around 13 volts, I've got a small denso alternator and a varley red top 20 battery.

So..what have I missed.....?

Many thanks in advance for your help.

Best regards

Ian

[grom_e30]

You can use win zip to compress the file and reduce its size for posting