To Lambda, or Not to Lambda…

If your CIS-Kjet equipped car was built after 1980 then has an oxygen sensor. The oxygen sensor controls a device called a Frequency Valve (or a Lambda Valve).

freq valve

The Frequency valve is used to “trim” the amount of fuel injected to allow the catalytic converter to work. As these older cars age, suffer failures, and worst of all shade-tree repairs, then this function stops working. If the Frequency Valve isn’t working then the system can’t be tuned. It won’t pass emissions, the mileage will be terrible, and it will never run right.

Lamda driver
The Lamda Driver from Unwired Tools is a simple gadget which drives the Lamda Valve at a constant precise 50% duty cycle. This “parks” the Frequency Valve at the mid-point of its adjustability. This simple device is the fastest and easiest way to take the oxygen sensor feedback loop out of the system, either as a troubleshooting tool or for when substituting later lambda equipped engines to earlier applications.

Here’s an example. This is the side view of a 1980 Porsche engine showing the location of the Frequency Valve:

CIS FV Edited

If you’re going to transplant this into a ’79 model then you’ve got a problem. OK, I get it, this situation represents more than just one problem, like how you got yourself into this predicament in the first place. Stick with me on this one, we’re not being judgemental here, just getting things to work. The Lamda controller is supposed to force the Frequency Valve to 50% if you disconnect the oxygen sensor. What if it doesn’t? What happens if the Frequency Valve is on all the time, or never turns on? That’s what happens if the electronics are not working or are not there at all, as in this case when en engine is transplanted.

Plug in the UT FV driver and the problem is solved, the fuel injection system now acts just like a pre-’80 version.  Many thanks to Owen at OC Auto Service in Laguna Beach for his many expert suggestions.  We’ve sold a few of these over the years but this is a “finished” form with the proper shape and connector for easy use



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