Which DME Should I Be Using?

[bcrdukes]

I have an 89 325i - North American, stock motor, 5-speed.

It has a 173 DME and the vehicle's production date is 10/88. Should it be using the 173 or 380 DME?

[Red88]

173 came with the car. Stick with it.

[bcrdukes]

I read somewhere that there are other DMEs for this production year and that the 173 was a bad DME.

[Red88]

The 153 DME was considered the "bad" one out of the two (153 in earlier models, 173 in later ones) ever offered in a 325i. I believe the 153 is Motronic 1.1 where 173 is 1.3, and the 173 results in a smoother idle and will throw far more codes when stomp tested.

[jlevie]

Essentially correct. A 173 or later is required for the stomp test to produce diagnostic codes.

[MR 325]

173 is said to be the best option for the 2.5 based M20 engine.

[T Verdier]

173 is said to be the best option for the 2.5 based M20 engine.

I have an 87 325IS and i replaced my DME with a 173 from this guy ^^^
and it is a smoother idle.