Additional capacity for early L-Jetronic

Charles cmorris at ix.netcom.com
Sun Apr 14 13:55:02 GMT 1996


Hello everyone... I'm new to this list, so I hope this isn't off-topic.
 I am modifying my '81 BMW 745i (factory intercooled turbo, L-Jetronic 
injection without an 02 sensor). Stock was 252 hp with the original 3.2 
liter 6 cyl, and 7 psi boost. Injectors are 273 cc/min. Now I'm running 
15 psi boost on a 3.5 liter engine, with a rising-rate (mechanical) 
fuel pressure regulator.
 Problem is, it takes 90-100 psi fuel pressure to support this much 
boost, and the injectors are not operating reliably. So - I would like 
to put bigger injectors on; readily available at about $50 each.
 From what I've read, though, the _minimum_ pulsewidth (idle) will 
become a limitation. If I put much larger injectors on, and stiffen the 
airflow meter spring, the ECU can't shorten the pulses enough at idle 
to avoid running rich. Any comments?
 The other solution is, additional injectors. Does anyone know of a 
reasonably priced injector controller? I'm about to make my own (30 
psig pressure sensor from Omega, 8748 or PIC16xx microprocessor, LM1949 
or CS452/3 injector driver chip) if I can't buy one first.
-Charles
cmorris at ix.netcom.com 



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