Hi Mark,

Thanks for finding this.

I did not know where to start. My first thought was if there is any other intake besides the Engine Air Intake. Bingo, there is, to the ECMs aka Central Electronic Box! I remember a small intake (for later ‘93s it is an exhaust) across the Engine Air Intake, on the other side.

Inside the Central Electronic Box, there are three ECMs (not sure if they are all attach together but AllData manual talks about the whole thing as one, for $900):

Traction Control Module (TCM)
Fuel Injection Control Module (aka MFI module)
Ignition Control Module (ICM)

Later ’93: Air from the AC system comes in the box and goes out through the front

Earlier ’93: Air comes from the front through an air filter. The paper filter needs to be replaced every 30k miles.

Ronjon
'93 850