This part was taken from a Motronic M1.7.3 engine control unit (ECU), which was commonly used on 1.6L & 1.8L 4-cylinder BMWs of the mid-E36 generation. While this chip was likely used on a number of ECUs, the specific one in this case had Bosch PN 0 261 203 661.

Functionally, this chip is a knock (also commonly known as “pinging” or detonation) signal processing device. Knock is detected by bolting piezoelectric microphones to the engine block, and when knock occurs it will generate a signal with specific frequency content. To the best of my knowledge, this chip acts as a tunable band-pass filter with a very narrow passband, which will signal the main microcontroller if enough energy is detected at the frequency of interest by outputting severity-proportional analog signals to two of the MCU's ADC channels. It also seems to provide some form of fault detection by exciting the piezo sensors and looking for a return signal.

Label (top):

30 098 (Bosch internal PN)
EB/0296
BJ129.1

Decap Steps:
(Bic lighter + water quench) x 3 cycles
Selective crushing with pliers and bench vise

Capture Details:
Imaging device: Keyence VHX-2000
Magnification: 1000X

Markings:
K10
CK10 (likely a reference to the commercial PN used by Bosch)

Note: This is a ~13X downsampled version of the original image. A full resolution version (41MB) can be provided. On the to-do list…