Raising my Idle, '75 L-Jetronic idle Options

[jeff dodge]

My idle is very low. maybe 500 RPM's. I would like to raise the RPM so less warm up is required to start driving without restarting everytime I come to a stop sign. Thank you, Jeff

[windforfun]

Tweak the big slot head screw on the side of the throttle body under the air filter.

[porschetub]

Tweak the big slot head screw on the side of the throttle body under the air filter.

Funny to read this as most ask how to reduce idle speed idle speed (air leaks) ,do adjust the air screw but make sure the timing is spot on before so ,cheers

[wonkipop]

My idle is very low. maybe 500 RPM's. I would like to raise the RPM so less warm up is required to start driving without restarting everytime I come to a stop sign. Thank you, Jeff

do you mean idle is low at 500 rpm during warm - up only?

[wonkipop]

Tweak the big slot head screw on the side of the throttle body under the air filter.

Funny to read this as most ask how to reduce idle speed idle speed (air leaks) ,do adjust the air screw but make sure the timing is spot on before so ,cheers

air leaks will mean L jets don't idle at all, or barely. not the other way around
you are thinking of D jets?

i suspect the OP is referring to a weak idle at warm up?
which won't be assisted by the idle air screw as the idle will be too high when properly at operating temp.
you only tweak the idle air screw with the engine fully warm for L jet (and anything for that matter - with as you note all other factors correct, valves, point gap etc).

he has not come back to my question above.
but it sounds like the classic lazy AAV that most of the L jets suffered from.
it does not open wide enough at cold start.
basically the AAV gets lazy with age.
these early L jets even when new did not high idle on cold start up.

mine has a lazy AAV - i bear with it and let it warm up for a good 5 to 10 mins before driving. just the way it is unless i send the AAV to the blokes up in queensland who do rebuild these things and promise to get them back into spec. but as i say even new the AAV was known to be productive of a slower cold start idle, not the usual higher 1200+ the D jets and most modern cars induce.

[L-Jet914]

Tweak the big slot head screw on the side of the throttle body under the air filter.

Funny to read this as most ask how to reduce idle speed idle speed (air leaks) ,do adjust the air screw but make sure the timing is spot on before so ,cheers

air leaks will mean L jets don't idle at all, or barely. not the other way around
you are thinking of D jets?

i suspect the OP is referring to a weak idle at warm up?
which won't be assisted by the idle air screw as the idle will be too high when properly at operating temp.
you only tweak the idle air screw with the engine fully warm for L jet (and anything for that matter - with as you note all other factors correct, valves, point gap etc).

he has not come back to my question above.
but it sounds like the classic lazy AAV that most of the L jets suffered from.
it does not open wide enough at cold start.
basically the AAV gets lazy with age.
these early L jets even when new did not high idle on cold start up.

mine has a lazy AAV - i bear with it and let it warm up for a good 5 to 10 mins before driving. just the way it is unless i send the AAV to the blokes up in queensland who do rebuild these things and promise to get them back into spec. but as i say even new the AAV was known to be productive of a slower cold start idle, not the usual higher 1200+ the D jets and most modern cars induce.

I wish there was an aftermarket company that produced new AAVs for our L-Jets. Trying to find a relatively inexpensive equivalent even used seems to be dwindling. I know the AARs for our L-jets was used across many different early fuel injected vehicles with the system. I need to check my AAR now to see if it's within spec.

[Ninja]

The 75-81 (ish) Datsun Z has this exact same problem with its L-jet system.

When it was still available in the 90s it was expensive!

Wish I had bought a dozen back then...

[StarBear]

Yes, lots of AAR variants. Just check that Aussie AAR repair guy’s site! All are a bit different. Was using an 85-86 BMW M6 unit but not acting right so got the original working and reinstalled. Huge (good) difference.
Hard to find. Rarely in working or dependable condition. Hopefully someone in US will parallel the Aussie guy and service. Not a bad sideline…..

[L-Jet914]

Yes, lots of AAR variants. Just check that Aussie AAR repair guy’s site! All are a bit different. Was using an 85-86 BMW M6 unit but not acting right so got the original working and reinstalled. Huge (good) difference.
Hard to find. Rarely in working or dependable condition. Hopefully someone in US will parallel the Aussie guy and service. Not a bad sideline…..

I wonder if anyone has tried fitting one of these to our little 1.8Ls I know the locating tab would have to be removed but it looks like it would fit/maybe work? Nissan(Z32/early Infiniti J30): 22660-45P00 discontinued but available used.

[wonkipop]

here is porsche's (or is that VW?) own tech document re the AAV on L jets.
issued in 76 when the cars were only 1-2 years old.

(document from the marvel of the marvelous Jeff Bowlsby website).

its not issued in relation to D jet cars, at that time L jet was termed AFC injection.

not a strong start from cold when new and it just gets worse with age.
where are we now, thats right, half a fricken century down the track. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/beerchug.gif) (IMG:style_emoticons/default/beer.gif)

[L-Jet914]

here is porsche's (or is that VW?) own tech document re the AAV on L jets.
issued in 76 when the cars were only 1-2 years old.

(document from the marvel of the marvelous Jeff Bowlsby website).

its not issued in relation to D jet cars, at that time L jet was termed AFC injection.

not a strong start from cold when new and it just gets worse with age.
where are we now, thats right, half a fricken century down the track. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/beerchug.gif) (IMG:style_emoticons/default/beer.gif)

I actually wish we had a high idle circuit for warm up like the D-jets and modern cars have today. The vehicle would warm up faster in my opinion. But I guess Bosch knew better with the early AFC haha.

[914rrr]

My L-Jet 1.8 idles great on initial start-up and a bit low as it's warming up / stalls on decel at traffic lights. After it's completely warmed up it idles well, maybe a tad bit high.

Is a lazy AAV the cause?

One thing I found that helped was having a fully charged battery, especially when the headlights and /or brake lights were on. Low battery voltage from sitting definitely made the stalling worse.

[wonkipop]

My L-Jet 1.8 idles great on initial start-up and a bit low as it's warming up / stalls on decel at traffic lights. After it's completely warmed up it idles well, maybe a tad bit high.

Is a lazy AAV the cause?

One thing I found that helped was having a fully charged battery, especially when the headlights and /or brake lights were on. Low battery voltage from sitting definitely made the stalling worse.

pretty much what mine does.
though the strong idle at start up only lasts 10 seconds at most.
(cold start valve and initial enrichment).
then iidle is weak (barely ticking over - 500 rpm on tach).
i don't let it sit doing that. bad on a start up after car has been idle a while
usually i have engine llid popped and hold the throttle open at about 1200-1400 for a minute or two. after that it holds a steady idle. this keeps oil pressure up and oil circulating and helps it warm up faster.
i can have decel stall when its still not fully warm - thats because i don't have a decel. (IMG:style_emoticons/default/biggrin.gif) but once its fully warm it stops doing that. the deccel stall happens if i have blipped the throttle and it comes down too fast, flapper moves too far, cuts fuel off then rebounds.
when its cold its enough to stall the engine, but not when its fully warm sometimes there is a momentary engine die but it regains composure on its own,

from your description i would think the following.
your AAV is lazy and there is not much you can do about that.
and possibly your decel valve is not opening. may have even failed.
you can try adjusting it if you have a 74 with the earlier valve with the nut on the end.

i have cleaned my AAV a couple of times. and checked its operation, both on the bench and hooked up in the car. it works. hence the lazy AAV conclusion. basically when its cold, because the bimetallic strip inside it has fatiqued it no longer leaves the open slot in it fully open in the resting (cold) position ready for a cold start. it certainly closes. if it didn't the idle would be high after warm up. which it isn't. as i say not a lot you can do. when new they were marginal as can be seen by the tech note originally issued by porsche and as they age they tip over the edge into not coping very well.