LM1 to control K-basic CIS?

[William Miller]

I'm posting here because of the experts avalible.

My 83 ROW CAB has K-basic.
I have a narrow band A/F meter and am considering moving up to a LM1. My fisrt thought was to get real time data, A/F ratio, control pressure (fuel) so that I could use this to tweek my k-basic system. With real info.

The thought came to mind as I was reading some posts on the LM-1 Some people mentioned that it could be used to supply modified info to the CIS controller on a K-lambda system.

My thought on my K-basic system is to let the LM-1 be the controller. The idea is to replace the control pressure regulator with a device that modulates pressure based on an electrical input provided by the LM1.

I was involved in some energy management applications (Air conditioning controls for buildings) in the late 80's. At the time Honewell made simular devices to control water flow and air damper positions for Air conditioners.

So I'm looking for comments on this idea.

Sorry if it's been discussed. I didn't have time this morning to do a search and it's been a while since I watched the LM1 threads.

So wada you think?

[350HP930]

While I think there is a device out there that already does such a thing, you could make an electronic device that converts the 5v signal from the LM into a controllable PWM signal for the lambda regulator.

If I was not getting rid of my CIS for EFI thats what I would do for a closed loop on a WBO2 with CIS.

[beepbeep]

Why not use used frequency-valve and bits from KE-Jetronic and feed them simulated narrow-band lambda output from LM-1?

[klatinn]

Hi,

The Lambda K/Jetronic already has such a device, the frequency valve. All you need to do is to program the LM-1's analog outs to simulate 2 narrowband sensors. One regular one with a switchpoint (0.45V point) at 14.7 AFR. The other with a switchpoint (0.45V point) at 12.8 or whatever WOT AFR you want to run at. Then disconnect the WOT wire from the throttle switch so the lambda computer always runs in closed loop, regulating the control pressure. Then use that same WOT switch to drive a relay that switches the O2 sensor input of the Lambda computer between Analog out 1 and analog out 2 of the LM-1.
Voila, a closed Loop WB controlled CIS system.

Regards,
Klaus

[William Miller]

I was away for a few days. Thanks for the great response.
I have to read each carefully to fully understand your ideas.
It seems like it would be relativly simple if I had a K lambda system, but I don't.

To clarify, my 83 ROW CIS is very simular in function to the late 70's USA cars. This is before lambda control. Although I have an O2 sensor it is only connected to the analog gauge. There is no controler, frequency valve, WOT switch, or the Lambda fuel distributer. (I do have a K- lambda fuel distributer on the shelf because the PO's wrench put the wrong one in my car. I now have the correct 81-83 ROW fuel distributer in it's rightful spot).

So:

While I think there is a device out there that already does such a thing, you could make an electronic device that converts the 5v signal from the LM into a controllable PWM signal for the lambda regulator.

Can you point me to the device you are referring to? Whats PWM ?

Why not use used frequency-valve and bits from KE-Jetronic and feed them simulated narrow-band lambda output from LM-1?

This is sorta what I hope to do, what bit's from the KE-Jetronic.

Could it be as simple as replacing the control pressure regulator with a frequency valve.

On my car the control pressure regulator has 3 functions. (I think)
1. Ramp control pressure up during warm up period.
2. Reduce control pressure when vacuum drops.
3. Atmospheric pressure compensation. (not exactly sure)

If I could replace/replicate these functions with a LM-1, Wide band O2, and a frequency valve. I think I would have a simple aftermarket closed loop system that would work to whatever limits the CIS system has.

That statement may be over-simplified.
I think the existing cold start system (valve and thermo switch) would remain. I think the Auxiliary Air Regulator, Auxilliary Air Valve and vacuum limiter would be optional depending on what the car is being used for. I would need to input a temp signal and maybe a vacuum signal or switch.

A control pressure sender and gauge would be nice, the sender could feed both the gauge and LM-1.

Will the LM-1 produce a pulsed (frequency) output that could be used by the frequency valve? Which way does the frequency valve fail? Open/closed with no signal? (maybe it should go in series or parrallell with the control pressure regulator for fail safe?

I wonder why Bosch didn't do it this way? In the K-lambda system, the control pressure regulator effects the pressure on the top half of the fuel distributer allowing the plate and piston to rise easier. The frequency valve effects the pressure on the lower half or the fuel distributer. They kept the warm up function seperate from the lambda control.

Enough thoughts from me for now.
Thanks for all the input.
Any and all thoughts are welcome.
Should this be posted somewhere else?


Would the LM-1 guy's be intrested in helping. It might be something that would help them and Wayne sell more of this product!

[87TURBO930]

So If I did something like this on my 930, It would make my car run in a closed loop mode even at WOT? And I would be able to set whatever AFR I wanted the car to try and achieve at WOT? I already have a LM1 in my car and this sounds very interesting to me.

[William Miller]

Another market for Wayne. I didn't even think of you turbo guys!

[beepbeep]

Hello!

LM-1 can be configured so it outputs "faked" lambda singal. With other words, it's acting lambda sensor. It won't output pulse-width modulated (PWM) signal but it's just a matter of finding KE-Jetronic "brain" that modulates frequency valve and connect it to LM-1 instead of ordinary narrowband O2 sensor...

LM-1 "faked" output can be configured so it "flips" at some other air/fuel ratio than just 14.7 so that gives some limited tuning potential.

[klatinn]

Hi,

I have experimented with the described setup with the LM-1, so have other people on this board. By programming the 'faked' O2 sensor signal of the LM-1 for WOT you can also vary the reaction time and control gain by varying the programmed slope of the faked WOT O2 sensor. I was planning to (but have not gotten around to it) to use a second PWM controller (or lambda brain) to control a regular EFI injector plumbed parallel to the WUR. The CIS Lambda frequency valve acts on the lower chambers of the metering valves in the fuel distibutor. The WUR acts directly on the control pressure. Because EFI injectors come in many different flow rates, it should be possible to find a flow rate optimal to your setup, wether its n/a or turbo. Specially rotary engines have injectors with ungodly flow rates. The EFI injector would not inject fuel, but just spray into a clamped on hose connected to the fuel return. To do this, the warm control pressure would need to be raised to allow more control authority to the EFI/Control pressure valve.
Just a little food for thought.

Regards,
Klaus

[William Miller]

Thanks for the food. I need to digest a while.
I was spinning this arround in my head last night and woke up with an idea.
As I mentioned above, my control pressure regulator effects control pressure from 3 things. Tempature, Manifold vacuum, atmospheric pressure. I forgot 1 device that I think was added on by Porsche because it's not made by Bosch. The Thermo Valve. This valve is in the vacuum line that goes from the Control Pressure regulator to the throttle body. It's normally closed and opens in 10-30 seconds as it's internal heter element warms up.
I think this may be a good control point.

The specifications book (little book) shows that warm control pressure shoulb be 3.4 - 3.8 bar with vacuum (Like at idle and light cruise) and it should drop to 2.7-3.1 without vacuum (Like at full throttle). I would imagine that the change in pressure is in some relation to the change in vacuum. So I don't think this operates as full open or full closed, but modulates gradualy with the change in vacuum. Internally it's done with a diaphram and counteracting springs.
Again this is the full throttle compensation design for my car. Maybe a little more eloquent than the throttle position switch?

So I'm thinking if I can replace the "Thermo - valve" with a valve that is controlled by the LM1 I might have a chance.

I like the idea better than the earlier because:
1. I don't have to screw arround trying to find something rated for fuel and screw arround with the stock plumbing.
2. The stock fail safe functions would remain in place.
3. The vacuum diaphram has a built in upper and lower limit of control.
4. I think / hope this is a large enough range of control to keep the A/F ratio at the right spot for different engine conditions.

Does anyone think this will work?

I think a simple Pressure electric valve would work as an on off. (not exactly what I want.) I'm pretty sure they make modulating valves in the 0-5v operating range. I know they make them for pnumatic building controlls, but that's pressure, not vaccum.

Any help on this is greatly appreciated!

[Doug Steinel]

Bill Miller says:

"I have to read each carefully to fully understand your ideas."

Now I read them carefully and still don't understand them!

[William Miller]

Don't give up! I'll lend you a book if your really intrested.
I only got intrested a few years ago after the PO's wrench screwed it all up!

BTW, at least someone is reading!