AFM and spring adjustment

[rjkoop]

I'm rebuilding my AFM because I never did a good job before. Here's a before picture. I think some paint or something was sucked into the AFM at some point because there is a lot of beige/white stuff inside.



It's cleaned now, rebuilt and reinstalled now but I'm worried the PO adjusted the spring mechanism (adjusted by the W thing at top left) that people say not to touch because it's adjusted at factory and shouldn't be messed with. How do I make sure it's adjusted correctly and wasn't tampered with?

Richard

[narfire]

Just a suggestion..... made a big difference for me. Take a look at the track the two pins travel on. Looks pretty worn from here. Anyway, if you can, loosen the screw and perhaps a slight bend in the pin arm to get the pins to travel over fresher track. About .5 to 1mm move makes a difference. After I had a bit of a stumble at idle and to about 2000 rpm I did the bend and move thing and the car ran so much better.
Chris

[rjkoop]

Just a suggestion..... made a big difference for me. Take a look at the track the two pins travel on. Looks pretty worn from here. Anyway, if you can, loosen the screw and perhaps a slight bend in the pin arm to get the pins to travel over fresher track. About .5 to 1mm move makes a difference. After I had a bit of a stumble at idle and to about 2000 rpm I did the bend and move thing and the car ran so much better.
Chris

For sure. I actually removed the connector, mechanism with pins (by loosening the bolt to slide the entire mechanism up and out) and the circuit board to clean. I reinstalled but didn't bend the pins. So I possibly just put them back to the previous position. I'll check again. Thanks.

Richard

[rjkoop]

Just a suggestion..... made a big difference for me. Take a look at the track the two pins travel on. Looks pretty worn from here. Anyway, if you can, loosen the screw and perhaps a slight bend in the pin arm to get the pins to travel over fresher track. About .5 to 1mm move makes a difference. After I had a bit of a stumble at idle and to about 2000 rpm I did the bend and move thing and the car ran so much better.
Chris

For sure. I actually removed the connector, mechanism with pins (by loosening the bolt to slide the entire mechanism up and out) and the circuit board to clean. I reinstalled but didn't bend the pins. So I possibly just put them back to the previous position. I'll check again. Thanks.

Here's an after picture. Looks pretty much the same so I'll adjust the pins.



Richard

[rjkoop]

Just a suggestion..... made a big difference for me. Take a look at the track the two pins travel on. Looks pretty worn from here. Anyway, if you can, loosen the screw and perhaps a slight bend in the pin arm to get the pins to travel over fresher track. About .5 to 1mm move makes a difference. After I had a bit of a stumble at idle and to about 2000 rpm I did the bend and move thing and the car ran so much better.
Chris

For sure. I actually removed the connector, mechanism with pins (by loosening the bolt to slide the entire mechanism up and out) and the circuit board to clean. I reinstalled but didn't bend the pins. So I possibly just put them back to the previous position. I'll check again. Thanks.

Here's an before (left) and after (right) picture. Looks pretty much the same so I'll adjust the pins.



Richard

[klweimer]

There's a good discussion at the end of this article on how to adjust the AFM based on O2 sensor readings:

http://www.hiperformancestore.com/ljetronic.htm

Kirk

[micbrody]

Take a slow and careful look at the link:

http://www.itinerant-air-cooled.com/vie ... php?t=7761

This author has excellent drawing and procedures for AFM adjustment

[rjkoop]

Take a slow and careful look at the link:

http://www.itinerant-air-cooled.com/vie ... php?t=7761

This author has excellent drawing and procedures for AFM adjustment

Great article! I'll try some things out and post the results.

Richard

[micbrody]

Before reading the article, I did "refurbish" the AFM. (PO had opened it up before based on seal). I cleaned up fuel pump contacts;
Cleaned the circuit board; cleaned and repositioned the tracking of copper arm contact. Afterward, i adjusted bypass screw using Voltmeter on oxygen sensor.
The only thing I did not do is check the spring tension. I did not have this article at the time; I could not find any identifying marks to indicated if spring tension changed; so i left it alone.

Car running well; occasional starting issues; "might" revisit the spring tension issue if the spirit moves me; otherwise the AFM seems to work great

[rjkoop]

When I was working on the AFM I noticed was sounded like a puffing sound when the engine was running. Thought it was an air leak somewhere but tough to identify. Then I found out what it was. I think spark plug 4 was never tight enough and it popped out. Hopefully it just came loose and didn't strip anything.

What's the best tool to tighten that spark plug? I have a socket wrench with a flexible joint but I find it's either too low (close to the engine) or too high (close to the hood latch). I guess the exact right length of extension would work best.

On a better note the engine does run much better after adjusting the AFM (but before the spark plug popped out! ) but I'd still like to measure the exhaust oxygen by attaching a voltage meter to ensure I have a good mixture.

Richard

[AriK]

13/16 spark plug socket, u-joint, extention. Use a real spark plug socket with the rubber insert so that you dont crack the ceramic.

[rjkoop]

Argh! Stripped #4 (closest to car interior) spark plug hole. That's why it blew out. Spark plug just spins when I try to tighten and that plug tightens fine in other holes. I guess only option is to remove head because it's probably impossible to get a helicoil/whatever in there? #1, #2, #3 would be fine but #4 looks like it's too tight. Any thoughts?

If someone thinks it's possible what size helicoil?

[rjkoop]

Bought the spark plug repair kit at Princess Auto for $24.99 and it worked great. Not a helicoil but more like a Time-Set. I removed the hood latch and top coolant hoses (where it goes into the head and I have my bleed valve installed) to get better access/angle. I'll put high temp RTV on the insert and hope for the best!

Richard