Checklist For Jetronic To Motronic Mi16 Upgrade

[davemar 16]

I've currently running an Mi16 1.9 engine with the 8v Jetronic setup with the distributor and all that jazz. I'm keen to upgrade it to the Motronic ML4.1 setup that is designed for the engine. I've got some of the parts so far:

 

1) Motronic ECU (ending in 139).

2) Air flow meter (ending in 202).

3) ISCV.

4) Wiring loom in a tolerable condition - will need checking though!

5) Crank position sensor with toothed flywheel already fitted (that's the nasty job done).

6) Mi16 distributor cap/arm.

 

What can be used from the existing setup which is likely to be the same? :

1) Throttle position switch?

2) Ignition amplifier? Currently got a 7-pin jobby and the Motronic loom appears to have a 7-pin socket. Are they the same?

3) Ignition coil? Currently using the cylindrical type, will I need to change to something else?

4) Injectors?

5) Temperature sensors?

Anything else?

 

Is there anything else I'll need?

 

I thinking of trying to get it tested by having the loom and ECU out of the engine bay to start with, so just disconnecting from the old loom the stuff that the new loom requires.

 

Ta, Dave.

[welshpug 1,662]

Temp sensor is the same, injectors are too IIRC.

 

Throttle switch is the same, Coil and amp are compatible.

 

Worth checking over the axillary sensor + starter motor section of the loom as well if its still the original one.

[Anthony 1,003]

Have you got the part that bolts onto the end of the inlet cam which the rotor arm then attaches to? That's removed when running a dizzy adapter.

 

Assuming by "cylindrical type" you're talking about the wing mounted wet coil, then really you want to replace that - you can use it if you modify the wiring loom and source a different king lead (what you have now would work if you're running a later style 8v dizzy cap) but you really are best doing it properly and using an Mi16 type coil that will plug straight into the loom and use a standard Mi16 king lead. Later 8v inlet mounted coils are compatible, but don't have the bracket to attach them to the inlet manifold - fine for testing purposes.

 

Test the TPS properly before using it, making sure that it works both at idle and full throttle ends of the travel. On an 8v you tend not to notice the idle one in particular being faulty, but it's much more ciritcal on the Mi16 as that's what triggers the ECU to use the ICV.

 

As above, I'd check over the whole loom before installing it in the car, as they're getting old now and lots of bits on them to cause issues even before you get to the issues caused by shoddy conversions to make them fit in 205's.

[davemar 16]

Worth checking over the axillary sensor + starter motor section of the loom as well if its still the original one.

Is that the brown multiplug, welshpug? On my current 8v loom I removed the brown multiplug and replaced it with modern watertight connectors, so

will do the same with the 16v loom.

 

Have you got the part that bolts onto the end of the inlet cam which the rotor arm then attaches to?

Yes, found that buried in a box of bits!

 

So apart from checking everything is working, it looks like it's only the coil I need to get.

[davemar 16]

Just another couple of quick questions.

 

Where does the coil go? For my current Jetronic setup have the cylindrical coil mounted on the wing, but it seems (for the Motronic) the square type coil mounts on the inlet manifold. However I've got a shortened manifold, so I'm not sure it'll fit there?

 

Also there's a couple of relays with the Motronic loom that seem to live in the engine bay somewhere. Wheres the best place for those?

[Anthony 1,003]

Coil is meant to bolt to the side of the inlet manifold, but chances are if yours has been shortened then it won't fit - or atleast not with both bolts. You'll have to work something out that works with your particular car and that you're happy with if that's the case

 

The relays usually end up sitting behind the drivers side headlight, which isn't ideal although putting them in a box to keep the elements at bay helps significantly. Personally I like to relocate the relays to inside the cabin next to the ECU where they'll be dry, but that involves extending the wiring and needs to be done to a high standard as otherwise you'll have no end of issues (given that those two relays between them power most of engine management related parts)