jpk

I believe on all of the 8 valve cars (definately on the '84), the two sensors are identical, so the same part can be used for either one.

There's a write up on clarks-garage.com on how to test and replace them, but the resistance test is only cursory - you need an oscilloscope to see the signal being generated by the sensor. You don't need to bother testing if you're just going to replace them.

You get to them from the top. Take a look directly behind the intake manifold - on the top side of the bell housing. You'll see a bracket with the sensors coming out. One bolt holds each sensor in (6mm bolt, takes a 10mm socket) It's a little tricky to get to the bolt - I used a 10" extension and a universal joint on my 1/4" socket. Make sure you don't drop anything down into the bell housing - a little precautionary application of duct tape to cover any holes isn't a bad idea...

As long as you don't loosen or remove the bracket, you don't need to worry about adjusting the sensor gap.

Follow the wires up to the bracket on the back of the cam tower. It's the standard 3 pin AMP connector that's used all over these cars. There's a clip to release (pry it off and remove it completely) then the connector comes apart. The bracket is sandwiched between the two halves of the connector.

I was lucky in that each of them came right out. I've heard horror stories of them getting stuck, (then you need to remove the bracket, and that's next to impossible with the engine in the car...) I'd suggest spraying them down with some kind of penetrating oil and letting it sit for a while.

The bosch part number is 0261210002. Google comes up with a bunch of sources. Bavarian auto seems to have the best price.

KuHL 951

Yes, the BMW E30 325 sensors work but they are incredibly longer than the 944 model. You can always coil the slack or cut/solder/seal to the correct length. Much less expensive also. You might check out Pelicans price also.

RMills944

Pelican wanted $179, the BMW is $68. I'm just going to replace both since they're originals from '84. I'm nont worried about coiling and zip tieing the sensors out of the way... not a problem.

The car sits around the side of the house most of the time now anyways, so I'll spray it and let it sit a week or 2 before I go at it.

Just so I know, what exactly do these sensors read on the flywheel? Do they sense the timing mark or a sensor attached to the wheel? what?

jpk

The bible of the early Bosch DME used to be here: http://frwilk.com/ It's down right now, but I'm hoping he'll put the we pages back up.

Basically, the sensors feed timing pulses to the DME. The speed sensor feeds one pulse for each tooth on the flywheel, and the refrence sensor feeds 1 pulse per revolution. between these two signals, the DME figgures out how fast the engine is reving and where it is in the combustion cycle, so it can time the spark and fuel.

btw- check out the sensors on bavarian auto site - they're the exact part (no extra wire to deal with)at $58.

sharky47

One of them reads a position (steel grub screw in the flywheel), and one counts the starter teeth to generate an accurate speed.

RMills944

Got a link (I've never used that site and I'd end up asking if it was the right part anyway)? If not, I'll pull it up after lunch. This site saves so much money - a LOT more than a membership for the site costs!

KuHL 951

I was incorrect it is the BMW E30 M3 sensor not the 325; too many parts ordered lately to think straight.

RMills944

I cought what you meant KuHL. Thanks for your and jpk's help. I found them - http://www.bavauto.com/shop.asp looked up part# 0261210002 under an 88 M3 and it's $56.95 each! Not bad - I'im just going to do them both and not worry about them.

Hopefully they'll come out easy!

RMills944

Nice, I found out my dad (lives in NH) is going to Bravarian Auto tomorrow to get a new tire for his bike... what a great coincidence!