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?

[Brian Fuerbach]

Appreciate all the replys. Took me a bit to read through and digest.

The car had a dual can distributor with both adv and retard connected. I hated the way it idled with the retard so I plugged it off, idled better. Finally changed to 123, best upgrade yet.

I will check the fuel pressure regulator to see if is functioning properly. The regulator looks like it has been replaced in the past as the cad plating looks nearly new.

At part throttle coasting the afr is not too rich, maybe high 10's -11. When I completely lift and coast it pegs full at 9. I live in the hills and if I use my gears to slow down the idle will be a little rough at the bottom but soon clears up. Was thinking it might be loading up a little bit. I started this topic because I had read that the AFR should go to 22 with the throttle closed during decel and mine did not, and partly because I am always looking for something to fix/improve on my 914.

[wonkipop]

Appreciate all the replys. Took me a bit to read through and digest.

The car had a dual can distributor with both adv and retard connected. I hated the way it idled with the retard so I plugged it off, idled better. Finally changed to 123, best upgrade yet.

I will check the fuel pressure regulator to see if is functioning properly. The regulator looks like it has been replaced in the past as the cad plating looks nearly new.

At part throttle coasting the afr is not too rich, maybe high 10's -11. When I completely lift and coast it pegs full at 9. I live in the hills and if I use my gears to slow down the idle will be a little rough at the bottom but soon clears up. Was thinking it might be loading up a little bit. I started this topic because I had read that the AFR should go to 22 with the throttle closed during decel and mine did not, and partly because I am always looking for something to fix/improve on my 914.

full test for the regulator is on previous page.
with car idling.
you pull off the vac hose to reg. should read 35 on a gauge.
put hose back on, should read 28. (all values approx or thereabouts).

both my fuel pressure regulators look beautiful and shiny cad plated.
both are at least 33 years old, suspect one is 48.
they did a nice job on plating them back in time.
(i have 2 because one is a visual emission cheat install for decel valve from back in the day).

topic is good, glad you started it.
i got into reading the patent documents for L jet. (IMG:style_emoticons/default/blink.gif)
and a technical explanation about how fuel despite being atomised by injectors coats surfaces of intakes rather than all hangs in air, but at another point in acceleration breaks free of surfaces. this causes two spikes and if it wasn't compensated for by the way L jet works the result would be a jolting rise in engine revs during acceleration. boy. (IMG:style_emoticons/default/sad.gif) (IMG:style_emoticons/default/smile.gif) i didn't fully understand it but i sure appreciated L jet a whole lot more. nothing to do with your issue, but i did at least stumble across the description of the why and how of the pressure regulator in L jet. which i had not understood properly at all.

i'll do some more searches when i get a spare moment and need a break from CAD.
see what i can turn up re rich on coasting. (IMG:style_emoticons/default/beerchug.gif) i'm interested to find out.

[Brian Fuerbach]

Appreciate all the replys. Took me a bit to read through and digest.
The car had a dual can distributor with both adv and retard connected. I hated the way it idled with the retard so I plugged it off, idled better. Finally changed to 123, best upgrade yet.

I will check the fuel pressure regulator to see if is functioning properly. The regulator looks like it has been replaced in the past as the cad plating looks nearly new.

At part throttle coasting the afr is not too rich, maybe high 10's -11. When I completely lift and coast it pegs full at 9. I live in the hills and if I use my gears to slow down the idle will be a little rough at the bottom but soon clears up. Was thinking it might be loading up a little bit. I started this topic because I had read that the AFR should go to 22 with the throttle closed during decel and mine did not, and partly because I am always looking for something to fix/improve on my 914.

full test for the regulator is on previous page.
with car idling.
you pull off the vac hose to reg. should read 35 on a gauge.
put hose back on, should read 28. (all values approx or thereabouts).

both my fuel pressure regulators look beautiful and shiny cad plated.
both are at least 33 years old, suspect one is 48.
they did a nice job on plating them back in time.
(i have 2 because one is a visual emission cheat install for decel valve from back in the day).

topic is good, glad you started it.
i got into reading the patent documents for L jet. (IMG:style_emoticons/default/blink.gif)
and a technical explanation about how fuel despite being atomised by injectors coats surfaces of intakes rather than all hangs in air, but at another point in acceleration breaks free of surfaces. this causes two spikes and if it wasn't compensated for by the way L jet works the result would be a jolting rise in engine revs during acceleration. boy. (IMG:style_emoticons/default/sad.gif) (IMG:style_emoticons/default/smile.gif) i didn't fully understand it but i sure appreciated L jet a whole lot more. nothing to do with your issue, but i did at least stumble across the description of the why and how of the pressure regulator in L jet. which i had not understood properly at all.

i'll do some more searches when i get a spare moment and need a break from CAD.
see what i can turn up re rich on coasting. (IMG:style_emoticons/default/beerchug.gif) i'm interested to find out.

Thanks for the input and appreciate you sharing your research. I come from years of tuning Weber and Dellorto carbs and now messing with L-jet. Will check the fuel pressure next. (IMG:style_emoticons/default/beerchug.gif)