Rescaling Injectors
Turbo Mini Forums

Evening gents

I posted a little while aqgo about the fuel pressures on my supercharged MPI as they were only 2 bar. Ive upped it today to 3 bar.

Im running an emerald and have rescaled the Injectors using the auto calculator within the ECU software. I think it went from 24mbps to 19.

The car starts and seems to run ok (only had a little blast up my road (private of course) as it wont be taxed till April.

But from the datalogger the AFR does seem a little erratic. Am i being completely too simple by thinking that i can make such an easy adjustment?

Thanks
Andy

You should be able to rescale with no trouble. The change must be sqrt(2/3) = 0.816
Idle may be erratic if injectors are too large. May be pressure was so low for this reason, to have more precision on light loads.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

if the ecu doesnt have an accurate figure for the opening time of the injectors and pulse widths are low at idle and cruise, then the afr's will be skewed non-linearly with the correciton :)

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Cheers fellas, i think its probably to do with the idle as suggested. I does have a tendency to stall now on the run up to junctions etc. Will put it back to 2 bar for now i think, at least untill i can get it back on emeralds rollers.

Most of injectors are specified for at least 3bars, meaning the spray pattern is not in the spec if they run lower pressure. I don't think it's so important on Mini siam ports, it's a crap anyway.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm