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The 1980-83 e21 320i had the 3 way cat and oxygen sensor, but how did they do that with K-jet? How did they keep the fuel/air ratio at the 14.7:1 level precisely, when the fuel injection didn't have a computer

The O2 sensor produces an electrical signal, so it has to be processed somehow.

This article mentions a controller of some kind that modulates fuel pressure through a valve that appears to be especially for K-Jet with lambda control :
http://cleanflametrap.com/kjetControlller.htm

I don't know much about E21s, and maybe you've seen this already. Just passing it along.

-Eric

528i-1981 wrote: ↑Sun May 03, 2020 1:01 pm The O2 sensor produces an electrical signal, so it has to be processed somehow.

This article mentions a controller of some kind that modulates fuel pressure through a valve that appears to be especially for K-Jet with lambda control :
http://cleanflametrap.com/kjetControlller.htm

I don't know much about E21s, and maybe you've seen this already. Just passing it along.

-Eric

Thanks Eric, yes I was wondering about this, given the 528i/633CSi/733i use the L-Jet computer to handle this. But of course there were lots of late '70s cars with K-jet.

It must get the job done, but I wouldn't think it would be as accurate as using a computer to do the job. Funny how cars as expensive as the Mercedes 6.9 and Porsche 930 only had K-jet and the 1975-80 Beetles had L-jet

E21s with O2 sensors used a frequency valve. It modulated the control pressure going to the fuel distributor which in turn controlled mixture.

Mike W. wrote: ↑Sat May 23, 2020 3:27 pm E21s with O2 sensors used a frequency valve. It modulated the control pressure going to the fuel distributor which in turn controlled mixture.

Thanks Mike, I always wondered how those cars worked, since the rest of the range had L-jet.

tlake wrote: ↑Sun May 24, 2020 2:26 pm

Mike W. wrote: ↑Sat May 23, 2020 3:27 pm E21s with O2 sensors used a frequency valve. It modulated the control pressure going to the fuel distributor which in turn controlled mixture.

Thanks Mike, I always wondered how those cars worked, since the rest of the range had L-jet.

It was cheaper to use and was more than adequate for passing smog and decent performance, hence it's popularity.