Help with specs for a 1994 M3 please

MarlinM3
Posts: 1
Joined: Wed Aug 22, 2012 7:44 pm

Help with specs for a 1994 M3 please

Postby MarlinM3 » Fri Aug 24, 2012 3:31 pm

Hi, I have purchased a Dash2, which is going into a Marlin sportster kit car I'm building in the garage. The donor is a 1994 BMW M3 3litre S50 engine. Does anyone have any data on what voltage range the sensors produce please for oil pressure, oil level, water temperature (and any others if you have them would be greatfully received!!). As I don't have the equipment to measure these parameters to hand (or the expertise more to the point!!). I assume you have to manually measure the reading of pressure/temperature etc.. and voltage from the sensor, and then plug the data into an equation. if anyone with a Dash2 has the information of the voltage outputs for the engine I'm using, it would really be of massive help, or if anyone knows if there is database somewhere with the voltages on, that would be a great alternative.

Thanks in advance!

Rob

osborni
Posts: 497
Joined: Fri Dec 07, 2007 9:08 pm
Location: USA, Michigan

Postby osborni » Fri Aug 24, 2012 7:37 pm

Are you using the BMW ecu and motor harness?

Does the ECU have a chip or is it flashable - i.e, can it be sharked? (if you open up the ECU case and you see an eprom that can be pulled, it's able to be "chipped".

You will want to run a separate set of sensors for the data - with one exception. You can tap into the TPS sensor wire for throttle position with no problem. It's 0-5 VDC.

You can also pull RPM off the harness that runs to the dash OR you can pick up the signal to one of the coils-on-plug. (there are a few other places to pick up RPM on the engine harness too)

The BMW ECU uses resistance type sensors for temperature.

The oil pressure sensor is just for the idiot light on the dash (IIRC). The motor will still run (for a little bit) with no oil pressure, but it needs temperatures for cold start enrichment.

The simple answer is to use R-T Sensors for temperature and pressure and use t-blocks or hose taps for oil and water.

Oil Temp comes off the oil distribution block or the pan plug.

Oil pressure also from the oil distribution block.

Water temp can be pulled from the top radiator hose, the thermostat housing (if you change it to an aluminum one) or from the head (depending on the year). Can also be pulled from the heater lines to the throttle body.

Sourcing a pressure sensor is simple as long as it takes 12VDC for power and puts out ~0-5 vdc and is not ratiometric. 5VDC supply sensor if you use the power supply on the Dash2 or an off-board linear voltage regulator.

(I have a 2000 M Coupe)

I'd also get a copy of the wire diagram for the year and motor. They are available on line for free.

IIRC, that vintage car will also need a speed input or it will go into limp mode (though not totally familiar with the chipped ECUs, just the flashable ones). The speed sensor is a VRS type and is located in the diff case on the car.

Obviously since Marlin specs out BMW mills, they should be able to support you on the functional install. There is some harness work that needs to be done with the OE dash - but it's not a big deal.
BMW 2000 M Coupe


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