Starting Point For AFM Adjustment Screw?

[RRoller123]

My AFM bypass adjustment screw is only about a little over 1/2 a turn from bottoming out, and something doesn't seem right with this. I don't have the necessary meter, but does anyone have an idea what a reasonable starting point from which to begin making adjustments should be? 1/2 a turn doesn't seem right. I think it was messed with by a prior PO, and there is no protective cap, which makes it very likely that this is the case.

Thanks.

Pete

[sptcoupe]

In addition to knowing what the starting point is, I would also like to know what the procedure is to properly adjust the AFM bypass.

[RRoller123]

It has to do with the CO levels and clean burning, correct me if I am wrong, but we need a meter to do it right, here are some videos on the whole thing:

http://www.youtube.com/watch?v=PqEBgS6hSGQ

http://www.youtube.com/watch?v=4yii7bq0eTU

http://www.youtube.com/watch?v=WtB3GC6zXPU

http://www.youtube.com/watch?v=7s985zg3s48

[sptcoupe]

Really helpful. Thanks.

So it seems the air bypass is really for minor fine tuning of the mixture, and the spring position for the main tuning point. Is that right? Also, does anyone know where I can get the meter?

[RRoller123]

I did a google search on: " L=Jetronic Tuning" and there is a wealth of info. One article says the starting point for the bypass screw is midway of the adjustment range. Mine is nowhere near that. Going to try it tomorrow and see what happens.

[htchevyii]

It is such a fine adjustment, I don't think that it really matters much unless you are trying to pass a smog check.

[RRoller123]

You may be right, I don't see a lot of change as I turn it, although the literature says that it takes a while to settle at each position, thus it needs to be adjusted slowly and in small steps.

Here is another VERY extensive treatise on the L-Jetronic system:

http://jenniskens.livedsl.nl/Technical/ ... tronic.pdf

[majicwrench]

"Back in the day" we thought of that adjustment screw like a idle mixture adjustment on a carb, which is basicly what it is.
I'm pretty sure there is no factory "starting point" . You could hook a volt meter to 02 and see the difference as you turn screw, but really, just use it to get the best possible idle, like you would on a carb idle mix screw. You do not have to wait, it happens right away.

[RRoller123]

I am going to take it fully out and spray the channel clean, cuz I don't see much difference at all, and logically there should be as you let more air pass by.

Pete