A different sort of FI question, because my alfa made me do it Options

[mmichalik]

So yesterday, I'm driving to the gym in my Alfa and it starts throwing codes on the dash.
I get the car back home, put the scanner on it and ultimately it was a P0101 code that put the car into limp mode and shut off a couple of other functions in the car.
I knew I didn't want have the luxury of getting a new Mass Airflow Sensor quickly so I went to the auto parts store down the road and got me a can of the MAS Cleaner.
30 minutes later, part is clean and back in the car and the code is gone.
But all of this got me thinking, did the original FI on our cars use a wire senor for the MAF or did it use something even more analog then that? I mean, it was almost 50+ years ago when it was designed.
I've always been afraid of the FI on the cars but, I've been toying with the idea of getting a FI kit from one of the vendors that are now producing them, for the 2056 that I am building.
Yesterday's experience intrigued me and maybe the FI isn't so difficult after all....

[Dave_Darling]

The D-Jetronic system used in the 1.7 and 2.0 914s used a Manifold Pressure Sensor to estimate the amount of air going into the engine from the air pressure inside the manifold. (With compensation for things like engine temperature, air temperature, and so on.)

The L-Jetronic system used in US-spec 1.8s did measure the air going into the engine, but it didn't use a hot-wire or hot-film system. It used a spring-loaded flap in the intake. Air coming in pushed the flap out of the way, and the amount that the flap (or "barn door" or "vane") was pushed was roughly proportional to the amount of air going in.

In both cases, the resulting information was used by a very funky analog electronic computer which told the injectors when to open and close. No look-up tables or anything digital.

Oh, and the European-spec 1.8 motors used dual single-throat carbs. Even more analog.

--DD

[GregAmy]

The L-Jetronic system used in US-spec 1.8s did measure the air going into the engine, but it didn't use a hot-wire or hot-film system. It used a spring-loaded flap in the intake. Air coming in pushed the flap out of the way, and the amount that the flap (or "barn door" or "vane") was pushed was roughly proportional to the amount of air going in.

The 80s loved the vane-door flappy measurer MAF. Even the 1.6L Miata, released in 1989 and used through 1992, used it.

It's interestesting that the bad-ass Motronic 1.2 as used in the vaunted 962 used the wire MAF. It was all about how much computing ability you had...and L-Jet and D-Jet had almost none (as I like to describe it, "a bunch of resistors and diodes flying in formation".

Today's even-cheapest EFI are heads-and-tails above any of that. It's like the old "you have more computing power in your pocket than Apollo had".

GA