Air fuel ratio Ljet Options

[Geezer914]

I am trying to adjust the air fuel ratio on me 2056 Ljet. I read the article that was posted a while back. I adjusted the wiper arm and set the idle at 1100 rpm (Raby 9550 cam) with the idle AFR at 13.2. When I check the high rpm the AFR is at 12.1. If I adjust the high rpm AFR to 13.2, (moving the large wheel 7 teeth CW) the the idle AFR is 16.9 with the mix screw all the way down. If I readjust the wiper arm to 13.2, then the high rpm AFR goes back to 12.2. Can't seem to find a happy medium. I know when you adjust the wiper arm it changes the mixture linear from idle to high rpm. How much more can I adjust the large wheel CW?

[914werke]

Just an FYI.. I had factory training on L-Jet back in the 80s. I understand the system. And I found out the hard way that the engineers at Bosch who designed this know way more about it than I do.

The air flow meter is designed to make the mixture richer with more airflow. When you change the spring settings in it, it changes the mixture curve. Rather than f**k with the insides of it, you can do things like increase injector size, or increase the fuel pressure to compensate for more displacement. And the difference between the 1.8 and a 2056 is not enough to cause an overly lean condition.

I have been running L-Jet on various 914 engines for 36 years. Never have I had an "overly lean" condition cause damage to the engine. And I have multiple air flow meters that have never been opened.

You can change things on your car at a your pleasure. And you can deal with the drivability issues that come with the reduction in spring pressure. I have already been down that road, and I was hoping to save you the trip.

Good luck.

Clay

Well great Clay, I appreciate any insight and advice you can provide. (IMG:style_emoticons/default/aktion035.gif) But admonishing me & suggesting I start from Zero isnt that helpful.
Clearly the reason for the post is to solve my EXISTING problems using a mixture of stock elements that may or may not have been messed with, & parts that would effectively mimic those installed on a 912E. The biggest departure from from stock is the cam installed, that while not over the top, apparently has enough overlap to impact the vacuum & simple start idle run.
As to overly lean, using the LM-1 it was easy to identity a VERY lean condition that was causing driveability (throttle load bucking) & could not be left as is.
So given that, where do you suggest I start, or questions youd ask?
Based on your stated "resume" this should be a slam dunk & benefit others who may find themselves down this path, but if you'd rather not troubleshoot in an open forum PM or call me
Thanks again (IMG:style_emoticons/default/beerchug.gif)

[wonkipop]

Just an FYI.. I had factory training on L-Jet back in the 80s. I understand the system. And I found out the hard way that the engineers at Bosch who designed this know way more about it than I do.

The air flow meter is designed to make the mixture richer with more airflow. When you change the spring settings in it, it changes the mixture curve. Rather than f**k with the insides of it, you can do things like increase injector size, or increase the fuel pressure to compensate for more displacement. And the difference between the 1.8 and a 2056 is not enough to cause an overly lean condition.

I have been running L-Jet on various 914 engines for 36 years. Never have I had an "overly lean" condition cause damage to the engine. And I have multiple air flow meters that have never been opened.

You can change things on your car at a your pleasure. And you can deal with the drivability issues that come with the reduction in spring pressure. I have already been down that road, and I was hoping to save you the trip.

Good luck.

Clay

Well great Clay, I appreciate any insight and advice you can provide. (IMG:style_emoticons/default/aktion035.gif) But admonishing me & suggesting I start from Zero isnt that helpful.
Clearly the reason for the post is to solve my EXISTING problems using a mixture of stock elements that may or may not have been messed with, & parts that would effectively mimic those installed on a 912E. The biggest departure from from stock is the cam installed, that while not over the top, apparently has enough overlap to impact the vacuum & simple start idle run.
As to overly lean, using the LM-1 it was easy to identity a VERY lean condition that was causing driveability (throttle load bucking) & could not be left as is.
So given that, where do you suggest I start, or questions youd ask?
Based on your stated "resume" this should be a slam dunk & benefit others who may find themselves down this path, but if you'd rather not troubleshoot in an open forum PM or call me
Thanks again (IMG:style_emoticons/default/beerchug.gif)

what clay says makes sense to me re airflow.
i myself would be very reluctant to mess with the AFM.
if i ever had to do anything with it there is a guy here in aus who rebuilds and tunes them and is trained to do it. we recently sent off an AFM for a 964 to have it rebuilt.
those kind of guys know exactly what they are doing setting one up.

re - the 912E did run slightly different injectors than the 914 1.8s.
they had slightly more flow. it is a 2 L engine so maybe porsche-vw had to do that.

you can google around and you will find some old shop talk forums that go into this.
i just did a quick google and turned one up.
had some of the blokes who are still active on thesamba discussing it.
L jet going on to bigger capacity 2L + engines with hotter cams.

what injectors do you have on it?