Possible to remove 1980 Lambda unit?

[78targa]

I am in the process of swapping out motors from a 1980 and a 1978 SC. So far everything is going just fine, however I am starting to get frustrated with the Lambda unit.

I have always had the O2 sensor unplugged and as far as I can tell the only thing the brain is doing for me is keeping the frequency valve on the CIS open to the 60% default.

Is there any way to remove the lambda unit from the CIS? It is sitting there like a parasite and just taking up space. How hard is it to backdate the CIS ? Can I just remove the control unit on the frequency valve?

It seems crazy to spend alot of time swapping over the harness and brain when all it will do is run in a default mode. The engine is out, so now is a great time to pry this thing off.

Any experiences out there? Thanks.

[john walker's workshop]

the 78 didn't use that system. use the 78 fuel distributor and warmup regulator.

[dd74]

I run an '83 with what I'm told is backdated F.I. from a 78-79. The Lamda unit was never installed with the engine. If Lambda assists in cold starts, a hand choke from a 2.7 works just as well - gives you something to fool with while the car warms up.

I don't know how hard it is to adapt older CIS from an SC to a newer SC engine. If you do that, though, also adapt the heads from your 78 - they breathe better than '80 heads.

[78targa]

Any way I can take the Lambda components out of the loop? What would happen if I removed the frequency valve altogether? Does the fuel flow become too much for the regulator? If the fuel flow becomes too much, is there a way to freeze the valve at 60% open without using the Lambda unit?

I am ignorant on this, but it seems like there has to be a simple solution...ok a new regulator is simple, but that is $$$. Is there another way?

The Lambda connects in three locations at the engine:
1. frequency valve
2. Throttle valve
3. Passenger side cylinder bank

I assume #'s 2 and 3 are there to send readings back to the Lambda unit...right? Then the unit sends a signal to open or close the frequenct valve?

If that is the case, then I should be able to unplug #2 and #3 without effect to the engine. That leaves just the valve...can I just remove the whole valve from that fuel line?

Here is a picture to help out:

[Eric Coffey]

CISWDP

(Continuous Injection System World Destruction Plot)

[dd74]

Originally posted by Eric Coffey



CISWDP

(Continuous Injection System World Destruction Plot)

You got a point, but you need to do all the other internal stuff to make those things effective.

[78targa]

I would like to get rid of the CIS altogether, and I will someday. But for now I promised my wife a low-budget solution in the form of an engine swap. My "while I'm in there" list has grown to over 2K already.

Right now I just want to get the '80 engine into the '78 and button it all up. Go figure a piece of junk emissions control is holding things up.

So anyone have experience removing the frequency valve from the fuel circuit altogether?

[Doug Zielke]

Originally posted by Eric Coffey



CISWDP

(Continuous Injection System World Destruction Plot)

LOL, Eric!
I think one of our "secret operatives" are going to have to pay you a little visit. Muhahahahaha!

[911nut]

Since you are on a budget you should leave the Lambda stuff on, leave the O2 sensor unplugged and set the idle CO to 3.5%. The car will run stronger (the rich mixture yields max torque; cheap HP improvement) and idle better. Otherwise you will have to do as John Walker says and if your going to go to all that trouble, get carbs.

[1980SC]

So anyone have experience removing the frequency valve from the fuel circuit altogether?

Yes, I do. It was done to my car before I purchased it.

Do not use the lambda style fuel distributor with the frequency valve removed. Bad idea. It will run way too rich. It took me months to figure out this was the reason my 911 blew out a thick black cloud of smoke everytime I went to full throttle.

You must do as J.W. says and use the k-basic fuel distributor and WUR.

Rob
1980SC

[1fastredsc]

If unplugging the the oxy sensor goes to a default of 60%. Why not just lean out the mixture on the sensor plate to compensate for the higher frequency valve value?

[john walker's workshop]

i would also use the 78-79 sensor plate housing because the sensor plate is bigger. everything is a bolt-on. all the extra fuel hoses, lines and special wire loom can be deleted in the process. you could go one better and use the 78-79 intake system complete, and port the 80 heads to the 78-79 size.

[Superman]

Did the '80 SCs have the 9.3:1 pistons? If so, then this would be a GREAT upgrade. '80 engine with the higher compression pistons, and use the heads and the entire intake system from the '78. Add SSIs and cams, and you could eat some Carreras for lunch.

[dd74]

I sent you a PM.

[ChrisBennet]

Originally posted by Superman
Did the '80 SCs have the 9.3:1 pistons? If so, then this would be a GREAT upgrade. '80 engine with the higher compression pistons, and use the heads and the entire intake system from the '78. Add SSIs and cams, and you could eat some Carreras for lunch.

Them's fightin' words! (to us Carrera owners)
I recently de-Lambda a Federalized '81 Euro SC. I removed the aftermarket O2 control box and changed the fitting on the warmup regulator to remove a tee'd in line that had an aftermarket cycling valve. I haven't installed the motor yet. Do I need to do anything else?
-Chris

[john walker's workshop]

the euro engine was basically 78-79 equipped already. what are the last 3 digits on the warmup reg? 069? i've got a euro 80 here that runs wierd.

[78targa]

I appreciate all of the replies. John, I know what you mean about just going ahead and backdating the CIS to a non-Lambda system. It makes sense and you know it will work. I have located a '83 Euro system, but Dang it, if I am going to do that why not just get an EFI and chunk CIS? For now I am enjoying the challenge of trying to sort out this fuel distributor.


I have found alot of information in the past few days regarding the Lambda system. I figured I might as well share the info I located. There is some great stuff on CIS out there, you just need to dig. (not enough to find a clear work-around as of yet)

Ayway, the Lambda system works as follows (explaination for the Lambda version of K-Jetronic by Jim Newkirk):

A car equipped with K-Jet Lambda also changes control pressure with a warm-up regulator (with pressures similar to a plain K-Jet system), but also controls lower chamber pressure in the fuel distributor by bleeding pressure through a frequency valve. By modifying lower chamber pressure, a change in volume of injected fuel is made, enriching or enleaning the mixture. The frequency valve is nothing more than an electrically duty-cycled fuel pressure regulator controlled by an on-board computer in response to an oxygen sensor signal. This system provides a more precise and rapid control of fuel mixture. Typical duty cycle on a properly running engine is 45 percent to 55 percent duty and fluctuating. A quick test of this system is to start the engine and test the frequency valve for vibration or noise -- it should vibrate. Also, unplugging the oxygen sensor will put the system in open loop and fix the frequency valve at a 50 percent duty cycle.

The link to the entire article can be found here: http://www.asashop.org/autoinc/june97/techtips.htm

It seems that 50% duty cycle is the default vice the 60% I believe I had previously mentioned.

Any interest in what the different CIS components look like and an explaination of what they do? Check this link out:

http://members.rennlist.com/jimwms/CIS/components.html

And for those with an interest in reading the actual manual, here is a link to the Bosch K-Jetronic manual:

http://www.phat-gti.com/downloads/boschtech-12d.pdf



So if the frequency valve affects the lower chamber pressure, why can't you remove the valve to create a static flow of fuel out of the distributor? Wouldn't a restricted fuel line work the same as a 50% duty cycle?
It sounds like if the frequency valve line is 100% plugged then fuel pressure gets too high in the lower chamber. Can you compensate by increasing the upper chamber to create an equilibrium? If there isn't enough adjustment in the distributor then a restricted line might be the ticket.


At this rate, I think I could have already moved over the Lambda unit...

[ChrisBennet]

Originally posted by john walker's workshop
the euro engine was basically 78-79 equipped already. what are the last 3 digits on the warmup reg? 069? i've got a euro 80 here that runs wierd.

John,
I'll look tonight when I get home.
-Chris

[Porsche962]

This is an old thread but wondering how everything turned out. Did the restricted line work for 78Targa?