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A 1983 320i should have either an 0280 001 301 or 309 ECU, and yes they are analogue L-Jetronic.
You can only chip the later 1988-on Motronic ECUs, and to fit one you will need to convert the loom and injectors, as per this article:
http://www.e30zone.net/e30zonewiki/inde ... tronic_1.3
A tip to make an L-Jet 320i a bit more perky is to:
a) Ensure the ignition timing is correct - advance it as far as you can to cope with modern fuel by loosening the distributor clamp and turning it a few degrees until it just doesn't pink (pre-detonate) when going up a hill or when accelerating in a high gear.
b) Remove the centrifugal rev limiter from the underside of the rotor arm; it brutally cuts the power at 6,000rpm, and is unnecessary since the ECU has a built-in 'soft-cut' limiter set at 6,250rpm.
