AFM Slamming Shut

[SteveinSLC]

OK, Its me again... still trying to get the 77 530i on the street.

Today while going back over all the items I have worked on I found that the car was not backfiring when I accelerated or backed off the throttle... it was the door on the AFM slamming shut.

I also found oil on spark plugs #1 and #2...

Any ideas?

I will copy some of my text from my Jiffy Lube post here.
It has the latest stats on my car.

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Currently the car starts right up and idles OK (little slow with some surging now and then). When I rev up the engine it purrs right along... but when going back to idle it occasionally backfires. If I try and drive the car it just has NO power at all... I can barely make it into 2nd gear... NEVER into 3rd... the more I press the throttle down... the more bogged down it gets.

I have adjusted the throttle body (including the throttle switches), cleaned the AFM inside and out... tried a 2nd AFM with the same results, timed it, verified the fuel pressure (35 psi), verified the distributer, points, grounds, new fuses all the way around...

I know that I have low pressure in cylinders 1 and 2... but it has been that way for years...

The only thing I can think of now it to replace all of the vacuum lines...

I have sprayed all around the engine looking for leaks... but nothing has come to light yet.

Any help is appreciated.

[Andrew in Calgary]

The AFM sends a signal voltage to the ECU based on the position of the door. If the voltage is incorrect, the ECU won't adjust fuel to match throttle position (we only have idle and WOT throttle switches). This is a possible area of concern. Even if the AFM is giving the correct signal, the harness may not be sending that signal back to the ECU.


Relevant Links:
ECU Pin-out
L-Jet Overview and related links

[Don Daynes]

Try replacing the capacitor wired across the points.

[SteveinSLC]

So I finally got back to the car tonight and tested a couple things out.

1st - I pulled the oil dip stick out while the car was running and it almost died out... had to put it right back in or the car would have stalled.

2nd - I then changed the oil in the car and discovered the smell of gas in the oil.

What size of capacitor is on the distributor? Where do I get another one?

The AFM slams open and closed as I get to higher RPM's... as I get near 4000 it is opening and closing quite often. (about every 5 seconds)

This one is kicking my butt.

UGH!!

[SteveinSLC]

OK, last night I had a some time to look into the harness a little bit.

I found a very poor repair job on the ignition coil.
Under quite a few layers of electrical tape I found a spliced in wire that had lost all of its insulation and had corosion all over it.

It was one of the main two contacts to the coil.

I didn't have the wire to repair last night, but I will give it a try tonight.

What do you think? Could this be it?

Steve

[SteveinSLC]

What kind of wire (guage, etc...) should I buy to replace this coil wire?

[Karl in KS]

What kind of wire (guage, etc...) should I buy to replace this coil wire?

Use similar to the original, likely 18 gage, but compare the wires to make sure. It will also make life easier in the future if you can find similar color as well.