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)

[ClayPerrine]

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)

Rich,
I apologize if I came across as admonishing you. My suggestion is not to start from Zero, but to eliminate a variable in your troubleshooting. Using a known good AFM would eliminate that from the items you need to check.

Do you have someone close to you with a running L-Jet car you could borrow the AFM from for troubleshooting purposes?

Clay

[914werke]

Rich, I apologize if I came across as admonishing you. My suggestion is not to start from Zero, but to eliminate a variable in your troubleshooting. Using a known good AFM would eliminate that from the items you need to check. Do you have someone close to you with a running L-Jet car you could borrow the AFM from for troubleshooting purposes?
Clay

No worries. (IMG:style_emoticons/default/grouphug.gif) I have several but all have been opened.
As it happens our old friend Troy @Messix dropped by out the blue the other day & while he's been spending all of his free automotive time on his Jeep, he still has his 914 that may be pressed into this effort. Not sure when the last time he ran it, but assures me it does (IMG:style_emoticons/default/biggrin.gif)
But hold on ... it just so happens I have a complete 912E motor I got from Ralph Meaney's shop after he passed. & it has a AFM on it that looks like its never been touched.
More to come..

[ClayPerrine]

Rich, I apologize if I came across as admonishing you. My suggestion is not to start from Zero, but to eliminate a variable in your troubleshooting. Using a known good AFM would eliminate that from the items you need to check. Do you have someone close to you with a running L-Jet car you could borrow the AFM from for troubleshooting purposes?
Clay

No worries. (IMG:style_emoticons/default/grouphug.gif) I have several but all have been opened.
As it happens our old friend Troy @Messix dropped by out the blue the other day & while he's been spending all of his free automotive time on his Jeep, he still has his 914 that may be pressed into this effort. Not sure when the last time he ran it, but assures me it does (IMG:style_emoticons/default/biggrin.gif)
But hold on ... it just so happens I have a complete 912E motor I got from Ralph Meaney's shop after he passed. & it has a AFM on it that looks like its never been touched.
More to come..

There were two different air flow meters. 74s used a 6 pin meter, and 75 used a 7pin. I think the 912E used a 7 pin but I am not sure. So make sure the pin count is the same.

Clay

[StarBear]

Rich, I apologize if I came across as admonishing you. My suggestion is not to start from Zero, but to eliminate a variable in your troubleshooting. Using a known good AFM would eliminate that from the items you need to check. Do you have someone close to you with a running L-Jet car you could borrow the AFM from for troubleshooting purposes?
Clay

No worries. (IMG:style_emoticons/default/grouphug.gif) I have several but all have been opened.
As it happens our old friend Troy @Messix dropped by out the blue the other day & while he's been spending all of his free automotive time on his Jeep, he still has his 914 that may be pressed into this effort. Not sure when the last time he ran it, but assures me it does (IMG:style_emoticons/default/biggrin.gif)
But hold on ... it just so happens I have a complete 912E motor I got from Ralph Meaney's shop after he passed. & it has a AFM on it that looks like its never been touched.
More to come..

There were two different air flow meters. 74s used a 6 pin meter, and 75 used a 7pin. I think the 912E used a 7 pin but I am not sure. So make sure the pin count is the same.

Clay

IIRC, yes, the 912E used a 7-pin AFM. In 912E LJet guide on Jeff B’s site.

[nihil44]

I have been outed by @wonkipop . I have been loitering in the shadows observing but I've had very little to offer in the foregoing discussions.
The specs on my project car are as follows
’73 2.0 DJet converted to LJet. 3 stud intake runners cut and welded to line up with L Jet plenum
’75 AFM – rebuilt by someone in California. Looks pristine inside
’75 7 pin ECU
No decel valve
FJ6 Standard Motor Products injectors
123 Distributor
Rebuilt throttle body by Phil Eslin
Current ailments – long crank to start and stumbles to stalling under load. Strong of petrol which seems to emanate from engine bay.
Booked into mechanic who has dyno and exhaust gas analyser. I am getting nowhere with my fiddling

Just some observations following which may be of use or interest

I made a tab to hold down cover on AFM for ease of observation only - @ClayPerrine . Hate the idea of silicone sealing


Inside ’75 7 pin AFM. Note counterweight on wiper and dob of silicone on top of black plastic cog indicating absence of tampering - @ClayPerrine . Looks factory quality. 2 white wires coming from temp sensor 1


Inside Kombi 7 pin. Small or no counterweight


Inside 6 pin ’74. Swapped out because of poor function. Note presence of counterweight and no silicone on adjustment screw and evidence of galling on adjustment screw from prior monkeying. No white wires coming from position of temp sensor 1


Note comparative size of intakes. ’74 has plastic tit in intake which is embossed with ‘1’ but no wires leading from it. Same position on Kombi intake is temp sensor ‘1’ – see wire connections

I have fitted the Kombi AFM to the car and it starts and runs but have not driven it.