Flywheel Reference Sensor Question

[downforce22]

I have an early 325i running motronic 1.0 and it uses 2 sensors to run the crank position sensor. The flywheel in the car has some damage on the reference pin and I found a lightweight flywheel. The problem is the lightweight flywheel does not have this reference pin as it was from a motronic 1.3 car. I looked at realoem and the part numbers are different.

Is there any way I can add the pin on the flywheel?

Early Flywheel Part Number Motronic 1.0: 11221706575

Late Flywheel Part Number Motronic 1.3: 11221706573

Does the material the pin is made from and location matter?

The location of the timing sensors changed with the introduction of the 325is in 9/86. 325e/es cars produced through 8/87 have the bell housing mounted sensors. The SETA cars (9/87-8/8 also have the front mounted CPS. All earlier 325 E30's have the bell housing mounted sensors.

Changing the CPS (or the Cylinder ID sensor) on this car is pretty easy with the car up in the air. It reads off the flywheel, so no worries about leaking transmission fluid.

The bottom sensor (labeled B on the bell housing) is the reference sensor (CPS). You can check resistance between two of the terminals (the only 2 with continuity) and it should be 960 +/_ 96 ohms (according to bentley manual). If that is good then you may be in the same boat as I am, and have a broken reference pin on the flywheel.

You can see the pin through the hole for the CPS, you can rotate the pin into position via the crank pulley hex on the front of the engine.

Good luck, hope this helps

Here was one guy's solution, what do you think?

http://www.r3vlimited.com/board/showthread.php?t=189226

http://www.r3vlimited.com/board/showthread.php?t=189326

Maybe I should just upgrade to motronic 1.3 to make everything easier!

[jlevie]

First of all you have a 325, not a 325i. While it might be possible to add the timing slug to a flywheel, that would have to be done perfectly for the engine to run right. You could, get a single mass M20B27 flywheel (which will have the timing slug) and have it lightened, if the goal is to run a lightweight flywheel. Otherwise just use the the flywheel as is.

Or you could turn the engine into a budget stroker by using the AFM, intake/TB, injectors, head, CPS, engine harness, and DME from an M20B25 engine.

[downforce22]

First of all you have a 325, not a 325i. While it might be possible to add the timing slug to a flywheel, that would have to be done perfectly for the engine to run right. You could, get a single mass M20B27 flywheel (which will have the timing slug) and have it lightened, if the goal is to run a lightweight flywheel. Otherwise just use the the flywheel as is.

Or you could turn the engine into a budget stroker by using the AFM, intake/TB, injectors, head, CPS, engine harness, and DME from an M20B25 engine.

Thanks for the response Jim. The car is originally an m20b25 with 885 head, afm, and intake/TB that should be the same. It is not an m20b27. I am contemplating swapping to motronic 1.3 and I would not have to worry about the sensor.

When you say use the flywheel as is do you mean the flywheel that originally came with the car that has the timing pin?

[jlevie]

To the best of my knowledge no M20B25 engine ever came with Motronic 1.0 and bell housing mounted timing reference sensors. That was only used on M20B27 engines up through 8/87. All M20B25 engines had Motronic 1.1 or later and used the front mounted CPS and Cylinder ID signal off the #6 plug wire.

If you plug in the last 7 of the car's VIN at realoem.com, what does that say it is? And what are the last three of the Bosch part number on the DME?

[downforce22]

To the best of my knowledge no M20B25 engine ever came with Motronic 1.0 and bell housing mounted timing reference sensors. That was only used on M20B27 engines up through 8/87. All M20B25 engines had Motronic 1.1 or later and used the front mounted CPS and Cylinder ID signal off the #6 plug wire.

If you plug in the last 7 of the car's VIN at realoem.com, what does that say it is? And what are the last three of the Bosch part number on the DME?

This confused me as well for quite some time. The code realoem gives me is 1271. Only available in europe and 5 speed configuration.

http://realoem.com/bmw/partgrp.do?model=1271&mospid=47265

The ecu is 35 pin with last 3 digits as 073. It is a 1986 325iX to be exact with 3.64 differentials (not sure how familiar you are with 325iX). Production date 11/85 and imported to the US through Texas many years ago. It had the 9.7:1 pistons and was federalized with some aftermarket O2 sensor to deal with emissions.

Here is a link of motronic ecu codes in e30 and their application, however it is missing a few.

http://84.45.115.78/e30zonewiki/index.php/Motronic

I have found several early model 325iX around the internet which can be seen by the early bumper valence (2 tow hooks built into frame), slightly different fender flares/ rear valence, chrome side moulding, early model m3 style tail lights, rear spoiler, chrome bumpers, rear headrests, etc. Notice these differences in the pictures below.

Mine also came with a metric spare tire, Mtech 3 spoke wheel, 3 setting vent fan, different fogs, and early euro cluster with 9 LEDs in the oil check strip vs regular 7 LEDs. My friend with a 323 has the same cluster and was federalized.

US spec 325iX




Early Euro 325iX







Or the even more rare 325iX baur:



Sorry to go off on such a tangent but it was very interesting for me to notice all the differences.

I would have to check to see if the sensors are in fact in the bell housing but the original flywheel has the reference pin and so I suspect it is necessary.

[jlevie]

Gotcha, it is a gray market car that was never imported into the US by BMW. All bets are then off. If the Bosch part number on the DME ends in 073 it could be Motronic 1.0 for an M20B25 engine. I don't know of any way to check that.

The flywheel itself means little. It could have been changed during a clutch change or auto to 5 speed conversion. What is more important is whether there are sensors in the bell housing.

Conversion to Motronic 1.3 should not be difficult if the head & block is set up as an M20B25 (cam and valve springs). You might have to change the AFM, injectors, ignition wires, and install the CPS along with the engine harness and DME. The 9.7 CR means that a US DME's tun won't be right, but you could fix that with a WAR chip and some dyno time.