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View Full Version : OBD 2 to OBD 1 sensor question for M52 OBD 1 conversion


El Gato Liso
05-05-2012, 06:51 PM
hi

im unsure about something...

the knock sensors from my m50 don't look good. the knock sensors on the m52 look great! the wires for the OBD2 knock sensors are bigger (diameter) while the OBD 1 sensors are smaller in diameter. Can I just cut and splice the M52 knock sensors to the M50 knock sensor plugs, to create make shift OBD 1 knock sensors?

the same thing goes for the coolant temperature sensor. the M50 has 2, the M52 has 1. can I just use the OBD 2 sensor and plug, and splice it the OBD 1 M50 coolant temp sensors plugs? it will be like making the plug and play conversion kit by Turner Mother Sports!

Thanks
-rob

North
05-05-2012, 09:29 PM
why not just keep the motor OBD2? Seems like so much effort to swap to OBD1

frankie591
05-06-2012, 02:01 AM
coolant temp sensors need to be obd1. Keep the blue top sensor to run the ecu, and use an e30 brown sensor to run the gauge. You can't use the obd2 coolant temp sensor because the output signal is completely different than that of the obd1 sensor.

Knock sensor I am not sure about. Since knock sensors are basically a microphone, I don't think there would be much difference obd1 vs. obd2. Just make sure that if you do splice the obd1 connectors onto the obd2 knock sensors that you have the cylinder banks corresponding with the correct connector.

Also North, obd2 tuning is more expensive, so converting to obd1 can be cheaper depending on where you get sensors/manifold/ecu.

cormier
05-06-2012, 10:11 AM
I'm thinking that the knock sensors aren't compatible.... I think it would have been documented if you could get away with using the obd 2 ones

As above, coolant temp is a nono for sure

El Gato Liso
05-06-2012, 10:24 AM
i wont try splicing the knock sensors

but the coolant temp, the obd1 has 2, they read out the same signal. 1 could be find, and i'd assume so since turner motor sports has the adapter for the ob2 sensor to obd1 plugs......otherwise, i'd have to drill and tap, which is something im not to keen on :)

cormier
05-06-2012, 07:01 PM
I remember people saying the tms adapter doesn't work for e30s-- because you need the brown top for your gauge to read proper, two different signals

Unless you don't want your gauge to work... You could re-dye one of the sensors to M12x1.5 and use the hole for the TB heater bung... Or vise versa to the hole

Or drill +tap in the flat spot between -- that wouldn't be that bad if you faced it downward for draining

ScotcH
05-06-2012, 11:34 PM
The knock sensors are completely the same, just the plug is different. Having said that, I've never spliced them myself, but one of our engines came with hacked up sensor wiring. Follow and compare the wiring digrams for each and splice away