L-Jet going full Rich on Deceleration Options

[Brian Fuerbach]

1974 1.8 with L- jet. Been playing with a wide band air fuel meter and noticed that when I lift the throttle the AFR goes to max value on the gauge. I thought it was supposed to go lean. I checked the throttle position switch and it checks out fine. Going to check the wiring harness next.

What else should I check? Decel valve?

[emerygt350]

I would bet it does, otherwise they would have just run it into the air cleaner pre-afm. But what does it say!!!? Perhaps the same thing it says when the aar is open? What does the fox say?

[wonkipop]

I would bet it does, otherwise they would have just run it into the air cleaner pre-afm. But what does it say!!!? Perhaps the same thing it says when the aar is open? What does the fox say?

here is a bit of the story emery.

i knew L jet did something where it cut off fuel.
hence the reason the fuel pressure regulator is plumbed into plenum vacuum along iwth decel.

we like to joke about these things being from the jurassic age.
but really its the ice ages and wooly mammoth era.

carbies were around with t-rex.

there is a bit of talking going on to the old lunar module era ECU and it can sort of think in a preconditioned pregrogrammed routine way.
its getting sensor information also from the dizzy to tell it what is going on during coasting after throttle closes.




so if you come off revs with the engine spinning fast enough it knows what is going on.
cuts off fuel until a certain point where revs are low enough and resumes supply despite throttle switch being at idle position. so there is a primitive neuron dedicated to that input.

must be similar with decel valve. knows that if flap is being pulled open a certain amount but throttle switch is in idle position then its got to do the decel thing and another neuron flashes on and does that routine.

so not exactly an overide, more a response to very particular environmental inputs.

its dumb, but kind of like a three year old or a chimpanzee. pick up the red box and you can have a peanut sort of thing.

still can't answer the fuel rich thing on deacceleration exactly.
but in a standard L jet set up with the original dizzy, there are a few things going on.
and all of them are really leaning it out. first no fuel. then some fuel and some air to stop it dying in its tracks (the decel valve) and then finally we are idle revs and it settling down.

but i had remembered right about the fuel cutting off. and i think it does it quite differently with D Jet but again i just know its different, but not how its different because i don't do D jet.