L-jet to Motronic on '81 B32?

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Charlesm3
Posts: 43
Joined: Wed Jun 29, 2016 6:42 am
Location: Atlanta, Ga

L-jet to Motronic on '81 B32?

Post by Charlesm3 »

I'm transplanting a great running Metric Mechanic Hiflow Sport ST 3500 into my '81. Someone told me recently that I should dump the Jetronic and do a full Motronic conversion now. This seems daunting. Is it doable? Worth it?
Advice will be well received.
Thanks in advance.
Charles Calhoun
'81 528i/535i Ascotgrau/Red, Euro hotrod
'89 e30 M3, Diamondschwartz/Black
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Mike W.
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Post by Mike W. »

The current school of thought seems to be to go to Motronic 1.1/1.3 off an E34 era car if you're going that route. The advantages are a better idle, better economy, cleaner emissions and the ability to do it anytime, no special flywheel is required. The disadvantage is a (slightly) custom wiring harness is required.

The advantage of Motronic 1.0a off an E28 535 over L jet is better idle control, better economy and cleaner emissions. A stock E28 motronic harness will work. Disadvantage is the need for a motronic flywheel.

If it was my car I'd just do the engine now, see if I liked it and was satisfied and go from there without any engine management upgrade now.
Mike W.



02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
Charlesm3
Posts: 43
Joined: Wed Jun 29, 2016 6:42 am
Location: Atlanta, Ga

Post by Charlesm3 »

Thanks Mike. Just the info I needed. I'm leaning towards your suggestion to stay put for a while after I swap the motor. I've got a long list of changes/upgrades so if it's easiest enough to do later I'll keep it as a down the road consideration.
Charles Calhoun
'81 528i/535i Ascotgrau/Red, Euro hotrod
'89 e30 M3, Diamondschwartz/Black
User avatar
Mike W.
Posts: 2889
Joined: Wed Aug 30, 2006 12:12 am
Location: Sonoma County

Post by Mike W. »

Almost forgot, that engine may have a motronic cam and need the adapter/repair nut to use a conventional distributor, no big deal, about $35 the last I knew.
Mike W.



02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
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