jetronic to montronic

[robs]

has anyone ever converted a old l jetronic engine to the later montronic?
if so what is involved in changing the engine loom?

[chrisr29]

Why do you want to do that out of interest?

Wasn't it just the earlier 323 the used l jet?

[Speedtouch]

Nope, early (pre '87/88) 320i also.

[surj]

yes i have i changed the complete loom in the car because it was a 1.8 loom normally you can just change the engine bay loom theres a plug in there which should fit i say should as some wiring is different on certain cars etc

[ed325i]

has anyone ever converted a old l jetronic engine to the later montronic?
if so what is involved in changing the engine loom?

Did you do this?

[Brianmoooore]

l jetronic is easily changed to the motronic set up by bolting on the motronic toothed wheel and crank sensor.
Stick the two engines side by side and swap anything that is different. All bolt on stuff.

[ed325i]

Brian what about the wiring of the c101 as the jet one to diffrent to the motronic one I am really stuck on this.

[Brianmoooore]

I don't have the pinouts for the old type engine loom connector (anyone?), but the ignition live in, starter signal in, and fuel pump out are the only wires required for the engine to run.
Everything else is instrumentation.

[ed325i]

The only info I can find is this link but its in german >> http://wp1016621.wp027.webpack.hosteuro ... f01593.htm

[Brianmoooore]

Google translator puts that into English.
Have copied and pasted it here, but lost the framework in the process. Still just about understandable: First number of a line is the C101 pin number, end of line is the M88 wire colour and pin number.
No idea if the M88 plug arrangement is the same as an early E30 though.


cut the angular engine plug off at the M88 engine and manufactured the cables to a new round engine plug according to the two lists. The allocation is very simple:


Engine plug E30
Function
presented cable of the M88 engine wiring harness

1 Generator 2 x blue of pin 1

4 Coolant temperature gauge 2 x brown-white of pin 4

5
Oil pressure
1 x brown-green of pin 14

6 Ignition plus secured
1 x green yellow of the pin 6

7 Ignition plus unsecured 2 x green of pin 11 and 12

11 SI 1 x white-blue of pin 15

13 Gasoline pump 1 x green-violet of pin 7

18 Starter 1 x black-yellow of pin 8

[m-dtech]

the haynes joke book has both motronic and jetronic wiring diagrams in it.

[Brianmoooore]

the haynes joke book has both motronic and jetronic wiring diagrams in it.

So it does!!
The L jetronic diagram is OK, but the motronic diagram is the very early one with the flywheel pickups.

[m-dtech]

the haynes joke book has both motronic and jetronic wiring diagrams in it.

So it does!!
The L jetronic diagram is OK, but the motronic diagram is the very early one with the flywheel pickups.

IIRC that makes no difference to the C101 plug, just the crank sensor is at the front of car and has an attachment on one of the HT leads rather than the two sensors on the gearbox.

[ed325i]

The lead on the HT lead is that for the diagnostic plug only or do I have to have it ?

[Brianmoooore]

The lead on the HT lead is that for the diagnostic plug only or do I have to have it ?

On early Motronic the pick up on the lead is just for the diagnostic socket, but on the later stuff it acts as a cam position sensor for the ECU. Engine will run without it, but run better with it.

[Ant]

Just seen this !I have the pinouts for both and a swop detail on Excel spreadsheet, Ian Haynes drew it up ages ago

email me for it , flatbars<AT>blueyonder.co.uk

Excel is required

[ed325i]

I have got some wires left over on the motronic plug.

Black ?
Red/Yellow ?
Yellow/White ?

[Brianmoooore]

black = engine speed signal to rev counter
red/yellow = 12V + feed to ABS system, switched by main DME relay
Yellow/white = ?? Not normally a yellow/white on the plug side, but yellow/white on the socket side (pin is the fuel rate signal to the instrument cluster.

[pacerpete]

L jet to motronic , Jeez some of you lot must be bored ?

[Brianmoooore]

L jet to motronic , Jeez some of you lot must be bored ?

On topic and constructive replies only, please, in the technical forums!
Keep this kind of stuff for 'pub talk'. if you must.

[ed325i]

Just seen this !I have the pinouts for both and a swop detail on Excel spreadsheet, Ian Haynes drew it up ages ago

email me for it , flatbars<AT>blueyonder.co.uk

Excel is required

I have not got excel

Is there any other way you could send it to me?

The fuel pump relay is working but there is no power to the coil and the starter motor carries on running when I turn the ign off.

[ed325i]

Its now running but the starter motor is running all the time and the engine carries on running even with the keys out of the ign the only way to stop it is to pull the battery lead off. Any ideas why its doing this ?

[Brianmoooore]

. Any ideas why its doing this ?

Because it's wired wrong!
Starter signal is always black/yellow in BMWs, and ignition switched + is always green.
Do you have these matched colour to colour across the engine loom plug and socket.

[ed325i]

There are 2 big black/yellow and 2 small black/yellow that connect together.
The green goes to green.

[Brianmoooore]

Measure the voltage on the green wire (a 12V bulb will do). Should be 12V with the ignition on and zero with it off.
Starter signal is a thickish black/yellow, and should only be 12V+ with the ignition key in the start position.
You sure that there is a second black/yellow pair?

[ed325i]

The green wire has ign live.
The thickish black/yellow is live when in start position only.
Now when I pulled the black/yellow from the starter motor the engine still turned over and stopped turning when it should. What power if any should be at that small wire from the main engine loom to the starter ?

[Brianmoooore]

Its now running but the starter motor is running all the time and the engine carries on running even with the keys out of the ign the only way to stop it is to pull the battery lead off. Any ideas why its doing this ?

So if the green (which goes to the ignition coil) is only live with ignition, how does the engine keep running after it's switched off?
Same with the starter motor. You've just said the black/yellow is only live in the start position, and the starter stops cranking if you disconnect it.
Why would disconnecting a dead wire have any effect?
The smallest wire to the starter motor will appear to have 12V+ on it if measured with a meter while disconnected. There are two relays in the fuse box that have 12V+ at one end of their coils, and the other ends of their coils are connected together and to this smallest lead.
The lead connects to the 'live' end of the starter motor, which, when the motor is not turning is effectively an earth, so the relays pull in.
When the starter is engaged, the wire becomes 12V+, giving zero volts across the relays, so they drop out.

[ed325i]

Brain I took the car down the road to day and it dropped a valve, so I can't do anymore to the wiring at the moment. Thanks for all you help so far.

[coconutbikinis]

Hi Brian, I'm posting from Australia. I've got an 84 C2 2.7 Alpina four door manual and have just purchased a 90 325i two door automatic.. I want to convert the 90 Auto into a manual and then I want to swap the all the good bits from the Alpina into the two door and the 325 motor into the four door.. What am i looking at parts wise, wiring loom etc? Are we talking different computers? its basically two stages to the job.. Auto to manual then running gear swap... Any E30 manuals that you can recommend that would be of help would also be greatly appreciated... Thank you

[Brianmoooore]

Hi! Welcome to the e30zone!
The best manual for the E30 by far, is the Bentley one, although it doesn't cover the M40 four pot engine, which, of course, won't concern you.
Not 100% sure of want you're trying to do. Do you want to end up with two manual cars, or do you want the '84 car to end up as an auto?
There's no great problems in achieving your aims, as it's only the different (pre and post face lift) styles of the engine loom to car loom connector, that prevent this being almost plug and play. The engine ECUs for autos are slightly different, but not different enough to cause any problems.

[coconutbikinis]

Thanks its good to be online with you guys, all your answers aswered by pro's... Not sure yet, It will probably end up being cheaper to make the 84 one an auto and bring over the manual gearbox to the 90 model as I will have to buy a manual gearbox and associated paraphenelia for both cars to come out as manuals.. If I transfer a 90 auto gearbox into an 84 what ECU would I end up having to use? There is also the question of jet to motronic.. I would obviously prefer the alpina motor to become motronic so there is the question of wiring looms auto to manual and bolting on the motronic toothed wheel and crank sensor to the alpina motor.. I can see a few different ways of skinning this cat however as always the easier option is always prefered... I like pug and play.. I may need to buy a new ECU from the wreckers to fit in the 84 to accept the gearbox... Or transfer ECU from 90 to 84 and buy a manual ECU for the 90... I'm I making any sense??

[coconutbikinis]

Simplifying the above post, how do I mate a 90 auto gearbox to a 84 manual jetronic ECU? Do I need a new ECU? If so which one? an 84 auto ECU or a 90 auto ECU?

[Speedtouch]

Wouldn't it be best to keep the relatively rare Alpina as it is, or is it a rusty turd?