Do you recognize any of that stuff?

[Olythekid]

For you the eagle eyes.

In a matter of a few days, my 86 635CSI Race Car (supposedly with a 87 engine) started to start/idle worse and worse when cold.

Now it just starts and shuts down right away then cranks and nothing.

In the rare cases I can nurse it to operating temp by joggling depressing the accelerator it finally idles 'ok' and accelerates like a bat out of hell.

So I start looking into stuffs, and it turns out I have a Motronic that says 91 535, and the serial number matches a 91 (The one that says D).

How can I check if the AFM waffle box is from a 91 535? Does it have to be, maybe it's from an 86? The ICV hums along and closes when turning the key, so I think it works. Do I have a harness/fuse box from a 91? Does it matters? What is this connector attached to the TPS connector? Does the engine looks from a 91? I'll check hidden the vacuum lines tomorrow, the ones that disappear under the manifold.
bm3.jpgBm1.jpgbm2.jpgbm4.jpg

[Bert Poliakoff]

You just have to find out the appropriate part number of the air flow meter required to match to your ECU which according to your picture is a 179. The number will show on your ecu. You can't go by the year as it could have been switched out at some point. Odds are the right one is there just judging from the pictures

[Olythekid]

Turns out the AFM that's on says E34 on the bottom … and … I found one that says '87 635' in a box in the trunk. So I'm pretty sure I have an 86 with a 87 engine and a Motronic/AFM from a 91 535i.

Frankenstein lives

[Bert Poliakoff]

You don't know what you have until you see the part numbers and then match them up. Right now all you know is what you thin you have,

[Olythekid]

Any website on matching part numbers?

[DaHose]

You can use realoem.com to look up by part number. You will be able to see all the models the part works on as well.

Jose