Is this an accurate way of tuning AFM

[86 shark]

I have been having lots of trouble getting my 86 635 to pass smog ( way too rich ).99,000 miles

I am probably going to test the cat next by using a vacuum test to see if it's clogged.

In the meantime I tried this:
Using a DMM I measured the output of the AFM at the output arm at idle (about 1000 RPM) Yes I know it's high

Car warmed up, new O2 sensor hooked up, AFM screw turned out 4 1/2 turns.

Tried to move teeth on AFM, tightening by 1 tooth did make voltage go down about .03 volts.
Decent idle was at about 1.09 volts

Anybody else ever try this, is this a waste of time?

Thanks,
Jim

[EuroGeorge]

Have a look at the attached. May shed http://www.bimmerboard.com/members/demetk/original/afm_adjustment_d.pdfsome light.

[86 shark]

Ouch EuroGeorge that link doesn't work.

[TowJamma]

Been needing to do this. Your theory seems sound, but the numbers don't jive with what I found online.

http://members.roadfly.com/louielouie/AFM_adjustment.html

http://web.archive.org/web/20070402083759/http://mysite.verizon.net/vzerdcib/e34a/id6.html

Haven't tried them on my '80, but interesting theory.

[EuroGeorge]

Ouch EuroGeorge that link doesn't work.

It's a PDF file. Need to download. :redspot

[Cjarvis]

Has the car ever passed smog in Colorado (+5000 ft) ? If not, and adjusting the AFM spring tension doesn't get you in range (14-15's at idle and cruising, 12's at WOT ?) , then you might need to look at a switch inside the ECU (see pic below). Maybe others with experience setting up these cars for higher altitude can chime in on what is needed. Lee's car came out of Colorado and I think he had some fun getting it to run right at lower altitude.
651453

EDIT: Adding these in case they are helpful:
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651455

[e24mpwr]

Has the car ever passed smog in Colorado (+5000 ft) ? If not, and adjusting the AFM spring tension doesn't get you in range (14-15's at idle and cruising, 12's at WOT ?) , then you might need to look at a switch inside the ECU (see pic below). Maybe others with experience setting up these cars for higher altitude can chime in on what is needed. Lee's car came out of Colorado and I think he had some fun getting it to run right at lower altitude.
651453

EDIT: Adding these in case they are helpful:
651454
651455

He's still working on it... :shifty (the details have changed, but I still wonder if the AFM straight...)

If you have some free time, I'll fly you here and stuff you full of good food and booze between sessions with the car...

[Cjarvis]

He's still working on it... :shifty (the details have changed, but I still wonder if the AFM straight...)

If you have some free time, I'll fly you here and stuff you full of good food and booze between sessions with the car...


Now there is an offer! Timing is good. I could make it a MTB road trip.

[86 shark]

Thanks for the info guys.

On the altitude question it passed smog for 6 years before this too rich problem.

The altitude could also be why my fuel pressure is a steady 40 slightly less than the 3 bar42.6 that is standard.

[86 shark]

Cjarvis,

Good tip, today I will take the ECU out and apart and look for these switch positions.

Great diagram of the switch positions.

Where it says mixture adjustment percentage, should I be looking to decrease the percentage as the car is running rich?

Thanks,
Jim

[86 shark]

Cjarvis,

Good tip, today I will take the ECU out and apart and look for these switch positions.

Great diagram of the switch positions.

Where it says mixture adjustment percentage, should I be looking to decrease the percentage as the car is running rich?

Thanks,
Jim

I took my ECU apart and of course it's an 059 which isn't listed.

The 059 switch was at position 0 and I moved it to position 3.

I had to use my smallest Torx bit ( sorry, size label fell off ) on it to fit the triangular position screw but I could feel the different positions.

[tschultz]

Since 059 isn't listed, I'll leave this here for you:

It is used to adjust the fuel mixture and retard the ignition timing in case you need to use substandard fuel. Notice that it has eight numbered settings. Normally you'd keep it at setting zero.

For the 535i (059 ECU):
Setting 0: Mixture 0%, Timing 0°
Setting 1: Mixture +3.9%, Timing 0°
Setting 2: Mixture -3.9%, Timing 0°
Setting 3: Mixture -6.3%, Timing 0°
Setting 4: Mixture 0%, Timing -3.1°
Setting 5: Mixture +3.9%, Timing -3.1°
Setting 6: Mixture -3.9%, Timing -3.1°
Setting 7: Mixture -6.3%, Timing -3.1°

[Cjarvis]

I took my ECU apart and of course it's an 059 which isn't listed.

The 059 switch was at position 0 and I moved it to position 3.

I had to use my smallest Torx bit ( sorry, size label fell off ) on it to fit the triangular position screw but I could feel the different positions.

Hey Jim, How did changing the switch position work for you? My guess is that since it was fine for six years before now, the ECU switch isn't the answer. Have you already ruled out the coolant temp sensor?

[86 shark]

OK, I have had trouble with my 86 635 USA auto passing smog too rich by a factor of 10.

Went and had a new muffler and new cat converter installed, both needed.
Down to smog place, failed by factor of 6, inspector suggested waiver.

Played around with AFM again , did switch to position 3 on ECU.

Down to waiver folks, great people and about 10 steps above Car Care Colorado.
Older fellow said it passed by a mile and was actually running a bit too lean.
Marked AFM spring and wrote down # of turns out on AFM air mix.
Loosened spring by 1 notch and it's running great.

This has been a 2 year battle and I don't know exactly what I did differently from previous tries.
On 2nd CTS and they both ohmed out correctly and a warmed up engine runs poorly and fast when I disco the CTS now so I think that circuit is working correctly.

I'm not sure the ECU adjustment did the trick, more likely I got lucky and hit the AFM adjustment just right or all the ground cleaning and contact spray eventually paid off.

I'm still puzzled but now it's time to work on my 71 Johnson 50 outboard motor.