Converting to Motronic 1.3

Motronic 1.3 was introduced to E30s 1988 when the facelift cars were launched, and was the final version of the engine management system used on these cars. For those with older vehicles, it can be worthwhile stripping out your older system to fit Motronic 1.3. Here's why and how it's done.

Benefits

The main thing anyone is going to want to know is why upgrade to M1.3 from the earlier systems. If your car is running fine as it is and you are happy with keeping it original, both in terms of performance and function then there probably isn't that much point in going to the effort. However if you are looking to increase performance or you are having running issues then it might be a good option, some may say necessity on the performance side of things.

• Improved accuracy of sensors and event timings for better fuelling and timing.

• Capability for a lambda to be fitted.

• Ability to remap chips for increased performance.

• Able to run a MAF instead of an AFM, again for increased performance.

• Better fault-finding with reduced number components with a sturdier construction.

• Better replacement parts availability.

Components

Sensors

Like all Motronic systems, 1.3 runs on a number of sensors, these are:

Sensor	Location
Air Flow Meter	Engine Bay
Intake Air Temperature sensor	Built into the Air Flow Meter
Crank Position Sensor	Front of engine block
Throttle Position Switch	Under throttle body
Engine Temperature Sensor	Engine head
Cylinder Identification Sensor	Fitted to HT leads
Lambda Sensor - catalyzer-equipped vehicles only	Exhaust downpipe

You will need all of these sensors to make your engine run properly. While you may already have some of these fitted, they may need replacing.

Jetronic systems also utilised a different version of the Brown Plug which drives the Temp Gauge. These older plugs were two-pin units, while your new system will only have one wire to connect to it. You will therefore need to replace your old Brown Plug for the new one-pin version.

Loom

The Motronic 1.3 system uses a wiring harness to connect all the sensors up to the ECU. Since the Motronic 1.3 ECU is more complex, it is fed by an increasing number of wires to better read and control the engine.

One end of the loom is the ECU plug. So that you can understand how everything fits together, check the pinouts for Motronic 1.3.

The other big connector will be the C101 plug. The C101 connects the engine loom to the main vehicle Loom, supplying a switched power feed as well as sending data back out to the Instruments. Two styles of C101 plug were fitted to the E30, and if you are converting from Jetronic or Motronic 1.0, then you will most likely have the older style plug on your vehicle. You will therefore need to wire your older plug to the newer plug found on your 1.3 loom.

Distributor

Jetronic engines have their distributor mounted in the engine block, while Motronic engines have it mounted on the head, driven by the cam shaft. You will therefore need the modern distributor, as well as the adapter and cover plate that fits to the end of the cam that allows you to attach the rotor arm.