BMW E30 323 with M20B25 Turbo
The engine
- Inline 6 cylinder BMW M20B25, 2.5 litres, ignition order 153624.
- Wastefire ignition with Ford EDIS wasted spark coils (stock 60-2 trigger wheel)
- Sequential fuel injection with no cam sensor and low-Z 720 cc/min injectors
- Custom engine harness
The turbo system
- PPF turbo manifold (pulse-split)
- External wastegate 50 mm from Boström Turbo Teknik
- 3.5" downpipe and exhaust system out through the (no muffler)
- Dump valve by Simon Marmander
- Custom large intercooler
- Holset HX50 turbo
The config and tables will be updated on this page, and documented properly given some free time. Here they are: [config.txt] and [tables.txt]
Bear in mind that fuel has not been set properly, including afterstart and other enrichments.
Changes from 2005
Ignition coils
Above 6000 rpm and some boost this engine ran into a problem with the ignition dwell. The Ford EDIS coils need 4 ms dwell but that was simply not possible since the method used in firmware at the time did not make it possible to use overlapping dwell. At 7000 rpm one revolution of the engine takes 8.57 ms and there are three ignition events. The time between each ignition event is 2.86 ms on a 6 cyl engine, and there is currently 400 us "coil off time" which means an effective 2.46 ms dwell on coils that need 4 ms. The problem would be more serious on a 8 cylinder engine.
The coil dwell limitation had not been resolved by spring 2006 when the car was on the road again. The [high power ignition coils] from Swedish company "Biltema" were chosen and driven in "dual out" mode, which means wasted spark. This has worked well, we have not found their limit yet.
Injector FETs
We have established that poor quality fuse holders caused 2 injector drivers to break. These holders were replaced with more reliable holders with spade connectors that attach directly to the fuse.
I have still not replaced the damaged FETs
The injector FETs can open if I work them manually (mdh..) (even with appr. 1A load ?) but give no measureable amount of fuel through the injector if used.
- My fear is that the remaining 6 FETs have been affected as well even though we seem to have no problem with the engine at higher load.
- If you can measure the voltage across injectors (preferrably at idle, with DVM in 20V DC mode), that will reveal if the pulsewidths are different. IMHO if FETs are measured to be able to drive 1A load, it's unlikely they will output different pulsewidths because of slow FET-opening or something.
Injector Flyback
The GenBoard/Manual/PowerFlyback has been installed and made a tremendous difference with the injectors. We have found a setting for the injector characteristics that work, more tuning will probably change this but it runs well at idle and the map seems properly flat and uninteresting in this area.\n
injopen = 0 injocfuel = 400 usec