Converting to Motronic 1.3

Motronic 1.3 was introduced to E30s in September 1987 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

Motronic 1.3 is a fairly complex system, but is based on previous versions of the Motronic system. You will need all of the following parts to get Motronic 1.3 up and running, but you may already have some of these parts depending on what your current engine management system is.

If your car is currently equipped with Jetronic management, you will need all of the following 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.

Installation

Any E30 can be converted to Motronic 1.3, but it is important to know what system you have fitted currently. If you're not sure, check the Engine Management page.

Once you know what you have, you can get hold of the components you need for the conversion and start from the appropriate step below:

From Jetronic

Camshaft rotor adapter (7) and dust cover (6)

Parts

• Distributor cap and rotor arm
• Camshaft rotor adapter
• Camshaft dust cover
• Air Flow Meter
• Oil Pressure Switch

Procedure

Distributor

Disconnect the battery, since we will be working with the Ignition system. You may also want to consider removing the radiator to give you more space to work.

Locate the distributor, mounted on the front of the engine block near the alternator. All of this assembly needs to be removed, which is done by prying apart the dust cover, disconnecting the wires, and unclipping the cap. Then undo the 10mm nut holding the distributor in place, and pull the entire unit up and out of the engine block.

In the space where the distributor was, you will need to fit either a blanking plate or the oil pump drive shaft.

If your distributor had vacuum advance/retard, then you will also have some rubber hoses lying around the area. Follow these back to where they meet the rubber boot or intake manifold and disconnect the pipes at those points. Blank off any holes with bolts and PTFE tape.

Now move up to the head, and located the camshaft timing sprocket. You will need to attach the camshaft rotor adapter and dust cover to the front of the sprocket; all of the holes should be in place for this to simply screw in. Once this is done, you will be able to mount the rotor arm and distributor cap to the head of your engine. Make sure that all the HT leads are connected in the right order.

Air Flow Meter

The Air Flow Meter is specific to each engine, but they are all essentially the same style. To remove the AFM, undo the jubilee clip to the rubber boot, unclip the electrical connector, and unscrew the 10mm nuts securing the AFM to its mounting bracket. Now wiggle and lift the unit, complete with air filter, out of the engine bay. With the entire unit removed, the AFM can be unscrewed from the air filter housing and replaced, then the assembly returned to the engine bay. You will not be able to connect the new AFM to the existing plug, but the engine loom is covered later in this article.

Oil Level Sensor

The existing sensor, located on the sump, uses a different plug to the Motronic engine loom, but operates in the same way. You therefore have two solutions to this; you can either cut the old plug off the existing loom and join it to your new loom, or replace the sensor with a newer one.

Now continue to the next step.

From Motronic 1.0

Parts needed:

• Toothed crank wheel
• CPS sensor
• CPS bracket
• ECU
• Engine bay loom
• CID sensor
• Injector plugs and loom

The main difference from M1.0 to M1.3 is the Crank Position sensor. All systems before M1.1 used two sensors mounted into the gearbox, while M1.3 uses one sensor at the front of the engine. You'll be fitting this new sensor, as well as a toothed wheel that sends a pulse through the CPS to the ECU. You'll also be fitting a Cylinder Identification sensor, which tells the ECU which spark plug is firing.

Procedure:

The most involved aspect is fitting the toothed crank wheel. This involves removing the radiator and the fan before you can access the existing pulley. Once you've got those off, undo the bolts holding the existing pulley, pull it off and fit the toothed pulley in its place.

While you've got all those cooling parts removed, you'll find it easier to mount the CPS bracket.

Now continue to the next step.

From Motronic 1.1

Parts needed:

• ECU

Procedure:

The differences between M1.1 and M1.3 all lie in the ECU, in the way that it processes the information it receives and acts upon it. Therefore, upgrading from M1.1 to M1.3 is as simple as plugging in a new ECU.