Classic BMWs

[SiC]

E28’s used LE Jetronic. Similar but different in a few ways.

BMW were the first to use digital engine management in 1979 with Motronic (DME or digital motor electronics).

I noticed that some mentions of LE Jetronic elsewhere. Wiki says there are 3 versions LE1, LE2, LE3. LE2 appears to do away with the cold start injector? LE3 from 1989 integrated into the airflow unit - called L3-Jetronic in that Bosch tech publication. Presumably a '85 E28 will be LE2?

[nebuchenezer]

Weld it, make it run and enjoy. Do not mgb it please

[Warren t claim]

I remember my E30 used to eat fuel pumps. Not that hard to replace once I'd removed the rear seat but the pump had to be taken out and replaced in two parts. Electrics were bomb proof though, I remember having to rescue someone from Chester with a fried alternator on his Belmont CDi and we used my E30 as a mobile charging system to get him home.

All ended well though because after getting him safely home I nipped back to the Shell garage he was stranded at just in time before it closed and banged Anita, the girl behind the counter, after a couple of drinks in a pub called The Watergate.

[The Reverend Bluejeans]

E28’s used LE Jetronic. Similar but different in a few ways.

BMW were the first to use digital engine management in 1979 with Motronic (DME or digital motor electronics).

I noticed that some mentions of LE Jetronic elsewhere. Wiki says there are 3 versions LE1, LE2, LE3. LE2 appears to do away with the cold start injector? LE3 from 1989 integrated into the airflow unit - called L3-Jetronic in that Bosch tech publication. Presumably a '85 E28 will be LE2?

Yours won’t have a cold start injector as it’s a facelift car with the deeper front apron.

[SiC]

Useful to know. So presumably LE2.

I won't deny it, the injection system holds as much interest to me as the whole car.

[The Reverend Bluejeans]

It’s a good system. The main failure point is the tall black fuel pump relay next to the fuse box. Sadly it is prone to clueless DIY fixes such as raising the idle speed on the throttle body. Never do this because it upsets the position of the throttle position switch and you’ll get savage mpg. If you have to adjust the idle speed do it on the air speed screw.

[SiC]

The idle mixture adjusting screw on the AFM? Presumably screwing this in to close the bypass will cause the AFM flap to open more and thus richen the mixture as it thinks more air is flowing? Therefore unscrewing to open up the bypass will cause the AFM flap to close up and thus thinking less air is flowing and thus weaken the mix.

[SiC]

What's the auxiliary air device like for reliability? Looks like it's something that can cause a whole manor of problems when it ages and stays closed because it's gone sticky from muck/carbon build-up. I'm surprised Bosch didn't go for an electronically controlled solenoid rather than relying on a heating element/engine heat to determine position.

Presumably it's a more analogue/mechanical version of an idle control valve solenoid that most later cabled Throttle Bodies got?

[The Reverend Bluejeans]

The idle mixture adjusting screw on the AFM

No. The air speed screw.

This is a tinkers paradise as you’re about to discover.

[The Reverend Bluejeans]

The aux air thing is water heated and it gums up with crystallised coolant. It starts out open and closes up as the engine warms up. NLA IIRC.