Motronic FAQ Clarification

[tacocat]

I read these.

http://firstfives.org/faq/e28_wiring_co ... rsion.html

http://firstfives.org/motronic.html

http://www.mye28.com/viewtopic.php?t=60306

Questions, what are the best parts cars and which version of Motronic is best? Sounds like 1.3 is ideal. Is it unreasonably difficult to adapt to an E12?

Edit: To be clear, I would like to adapt 1.3 fuel/ignition to my current M30B28, perhaps with E34 or E32 electronics.

[Falkenberg]

Just the FI, or a whole engine?
There is more information on this forum, the search function could help here, I suppose.

[Pierre]

You do not want to adapt a 1.3 motronic to a 1980 motor. The ignition system is integrated in the motronic which can not control the older distributor type on the ealy M30s. There are numerous other sensors, connectors and valves that diid to be added or rewired or bypasses.
If you want to retain your engine and improve the system, you may want to consider a Megasquirt unit. I have not done but spoken to many who have and I am planning to do so on my E12. It takes some tinkering but it could be rewarding.
Or you can drop a complete motor from a 90-92 E34. Earlier E28 motors are also very good but the E34s are even better. They are not very expensive and the swap is not very hard.

[tacocat]

Just the FI, or a whole engine?
There is more information on this forum, the search function could help here, I suppose.

FI and ignition. See edit in first post.

Good suggestion. I have searched around a bit and find little definite information. This link helped me onto 1.3:

http://www.firstfives.org/bboard/viewto ... t=motronic

The ignition system is integrated in the motronic which can not control the older distributor type on the ealy M30s.

Correct, so wouldn't you swap it out? The second link in my first post seems to suggest removing the distributor/timing cover and replacing with the distributor used on the Motronic system of choice.

B35 conversion would be awesome, but is a bit outside the scope of my current intentions. I'm just trying to ditch L-Jet and get better than 17mpg

[Pierre]

I guess you could, but it sure looks like a lots of parts, bits and pieces.
The bigger concern is that the Motronic 1.3 ECU is set up (injection and ignition) for a 3.5, including cam timing, compression ratio, and motronic is not externally adjustable. It will somewhat adapt within a range based on the sensors' inputs. Will the motronic curve work on the 2.8? Even your TPS and AFM signals assume a certain displacement that is burnt in the ECU chip. And even if it does, does it work such that you get better economy and/or better mileage?
I find that anecdotal evidence when people claim a significant improvement after a conversion, that they compare a car that was running poorly due to undiagnosed issues, when in reality, the car just needed some work done on its system. If you car is running well, I am afraid you will be disappointed with a 1.3 swap.
Now, if you have a donor vehicle or have all the parts already and have the desire to play, then by all means, experiment But be prepared to maybe put it all back.
But as I mentioned in my previous post, a megasquirt will yield significant improvements over a well running L-jet. But it's not a simple bolt-on or plug and play.

[Falkenberg]

Didn't catch the later edit, sorry.

I think you can actually keep the old distributor, you just don't use the advance mechanism anymore. The coil and spark timing would be controlled by the motronic, the old distributor only distributes the high voltage to the correct cylinder.

You need to think of a way to mount the ignition timing sensor on the timing chain cover on the exact right spot, swap the front flywheel, put the temperature sensor for the motronic on the front water distributor. Fuel rail, injectors, intake (tps!), air flow meter. Not sure if the ports between head and intake match though. I think 3.5 motronic could have bigger ports.

Member Blaise did actually a motronic (as far as I recall) conversion (including injectors) while keeping the old banana intake. Very nice. But he then either swapped or re-chipped the ecu to get things to run smooth.