‘74 1.8L L-Jetronic Cold Start Low Idle, Mystery solved! Options

[emerygt350]

Ok; here’s my morning test:
14F, “feels like” 3F. Sunny.
Used tach for rpm data.
Cranks to start: 7
Secs to start: 3
Initial idle 1100 rpm
1:30 idle 1300 rpm
2:00 idle 1050 rpm
3:00 idle. 950 rpm
4:30 idle. 900 rpm
5:30 idle. 950 rpm
6:30 idle. 1000 rpm
9:30 idle. 1000 rpm
10:30 idle. 1025 rpm
Steady at 1025-1050 after that.
All seems well in New Jersey…. (IMG:style_emoticons/default/biggrin.gif)

That looks really good.

[Van B]

That is a perfect result man! Your AAV closed when it was supposed to and even though the engine wasn’t quite fully warm yet, it looks like it got there in short order.

What is your tach error? Are you at 800-900 on the timing light?

[StarBear]

That is a perfect result man! Your AAV closed when it was supposed to and even though the engine wasn’t quite fully warm yet, it looks like it got there in short order.

What is your tach error? Are you at 800-900 on the timing light?

Yep; spot on. Interpolated tach readings to the closest approx 25 rpm. (IMG:style_emoticons/default/biggrin.gif)

[Van B]

Right but what is your actual tach error compared to a timing light?
Idle should be 800-900 RPM per the manual.
For reference, my tach looks to be optimistic by 50-100 RPM compared to the gun.

[wonkipop]

nice work L jet-ters.

(i can't tag your name Van, tried all the variations, no go).

fantastic confirming the operation of the c s i van.

if it is 65F that it cuts off with an original and correct thermo-switch that is an exact match for the EPA definition of a permitted AECD. (aux emissions control device).
- devices allowed to work below 68F and above 86F for a limited amount of time to permit engine starting and initial warm up or prevent engine damage. this is one of the devices that triggered scrutiny by the EPA of the set ups in earlier D Jet cars from 72/73 MY and got VW into trouble - they had been using similar switches to permanently shut off the emissions equipment below 65F).

very interesting to look at StarBears numbers on cold start up.
mirrors mine - but higher.
3 minutes to 4/5 minutes is more or less what mine is doing, but its barely keeping going in my case. my warm idle is set lower at about 850 to 900. n my case its doing what StarBears does but at all times around 150-200 rpm lower. also StarBear has his cooling flaps hooked up so that is helping his and hindering mine (mine is disconnected).
its not doing it now, but its not winter.

i'm thinking maybe L jets staggering or subsiding after initial start up for a short time is an inbuilt historical feature. caused by the EPA ruling on that thermo switch and strict definitions of when and how the switch can work and what the car is allowed to do during warm up. normally its not so noticeable, but any one component out a bit and that stagger around the 3 minute mark gets very perceptible.

StarBears is likely working close to like its supposed to.

(IMG:style_emoticons/default/beerchug.gif)

Van - my sense of what inputs cold enrichment is that it is the CHT and also the second sensor in the AFM (incoming air temp) and these input to the ECU to adjust how long the normal injectors stay open? you have a new CHT so that info should be good to the ECU.
the other one is more problematic in the AFM as i think its damn near impossible to replace if its not working right.

[wonkipop]

apologies for not getting to mine and giving some input.

the last stages of falcon ute got in the way of the plans of mice and men.
(always takes more time than you think).
this thing had a hell hole that proves satan was only practising on 914s.

emery will like it? - being a ford/mustang man.
i didn't do the paint. the master (he who undoes my amateur operations on the 914) operated the paint bazooka. i will be permitted to weaponize on the inside of the pick up tub for target practice. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/beerchug.gif)

its a pity you don't live down here StarBear. I could have fixed your jacking plate for you.
i've got expensive rates but. would have cost you a six pack of yebisu. (IMG:style_emoticons/default/drunk.gif)

[emerygt350]

Looking good! I just picked up a nice gravity feed sprayer for my efforts next spring. Been thinking about the gt350 quite a bit since the salt went down.

[wonkipop]

@Van B
@StarBear .

in the interests of collective ability to be in different hemispheres and opposite seasons.

34C (about 93F) here today.
car started instantly.
did not even do the momentary quick revs.
no engagement of thermo switch on csi?

started at weakish idle of just at bottom of tach. 750-800 rpm.
but did not falter or go weak. just went slowly up from there.
after 4 minutes it was at 950 and steady.
felt so good about that had to go out for a quick (IMG:style_emoticons/default/driving.gif)
put a hat on and 50 plus sunscreen. (IMG:style_emoticons/default/sad.gif)
its lockdown quiet here again (without the dicktator locking us up).....all the folks are spooked by omicron.
----> led to great pleasure on empty city streets until i started feeling skin on my hands burning. gave up after 20 minutes and retreated to shade of my studio.

as i was pulling it in a rotund gent walked past and said - sh$t a nine one four.
man i've never seen one. can i have a look.
he was beside himself. looked about 65.

not like 30 years ago when i just got sneers. (IMG:style_emoticons/default/beerchug.gif)

[Van B]

@StarBear and I have our NOS injectors out getting tested. Once I get them back I’ll install the Nissan thermo switch, flush the fuel lines, new filters, and new injectors. I’m feeling cautiously optimistic that the switch and injectors are the solution. But, I’ve also been wrong every other time so, we’ll see. It’s been between-5c and 1c every day and for the next week or so. I’ll have amole cold start opportunities lol!

Sorry to hear that the brain washing has taken full hold down there but, at least there’s a silver lining to be found! Here in the DC area folks are drinking the kool aid too. It’s nice when I can get to the real America and see folks enjoying life.

[wonkipop]

keep us posted on the results of endeavours.


unfortunately the UV levels are curbing my enthusiasm for rolling here.
i love the heat- its a dry heat....but this summer there is an incinerator pointed at you.
(tomorrow it goes tropical and humid!?).
UV levels from the BOM are off the hook.
put cracks in a 914 dashboard in 5 minutes that take a decade in california.

putting it down to lack of planes in the air.
i'm ready to beg the USAF to do some tree top fly overs of my neighbourhood with B52s and lay down some dirt trails in the atmosphere.

as a bonus there is a good opportunity to do some carpet bombing practice for the benefit of the free world. (IMG:style_emoticons/default/beerchug.gif)

[emerygt350]

Was -15 F here yesterday....

[StarBear]

Balmy mid teens F lately here. No driving with residual road salt.
Nexteeek will pull it out and start cleaning up that repair patch. Got the jack triangle and doing some prep on the metal replacement patch.

[StarBear]

@Van B
@StarBear .

in the interests of collective ability to be in different hemispheres and opposite seasons.

34C (about 93F) here today.
car started instantly.
did not even do the momentary quick revs.
no engagement of thermo switch on csi?

started at weakish idle of just at bottom of tach. 750-800 rpm.
but did not falter or go weak. just went slowly up from there.
after 4 minutes it was at 950 and steady.
felt so good about that had to go out for a quick (IMG:style_emoticons/default/driving.gif)
put a hat on and 50 plus sunscreen. (IMG:style_emoticons/default/sad.gif)
its lockdown quiet here again (without the dicktator locking us up).....all the folks are spooked by omicron.
----> led to great pleasure on empty city streets until i started feeling skin on my hands burning. gave up after 20 minutes and retreated to shade of my studio.

as i was pulling it in a rotund gent walked past and said - sh$t a nine one four.
man i've never seen one. can i have a look.
he was beside himself. looked about 65.

not like 30 years ago when i just got sneers. (IMG:style_emoticons/default/beerchug.gif)

Love driving up to the petrol stations and having the young kids screw their brains back in. The young fillies smile (sometimes) and wave when driving by. Have had two “older” gents ask me about it while at a stop light. None in the wild around here any more. (IMG:style_emoticons/default/sad.gif)

[emerygt350]

Balmy mid teens F lately here. No driving with residual road salt.
Nexteeek will pull it out and start cleaning up that repair patch. Got the jack triangle and doing some prep on the metal replacement patch.

sigh. I don't think mine will see daylight until April...

[StarBear]

@StarBear and I have our NOS injectors out getting tested. Once I get them back I’ll install the Nissan thermo switch, flush the fuel lines, new filters, and new injectors. I’m feeling cautiously optimistic that the switch and injectors are the solution. But, I’ve also been wrong every other time so, we’ll see. It’s been between-5c and 1c every day and for the next week or so. I’ll have amole cold start opportunities lol!

Sorry to hear that the brain washing has taken full hold down there but, at least there’s a silver lining to be found! Here in the DC area folks are drinking the kool aid too. It’s nice when I can get to the real America and see folks enjoying life.

@Van Will be most interested in your thermo timer investigation. I can get one but a bit expensive as a maybe spare for a part not usually known to fail, though mine is the original nearly 50 year old part. (IMG:style_emoticons/default/idea.gif)

[Van B]

You should check yours. Manual says put a multimeter on it below 68F and confirmation tone/continuity. If you get the beep, then you’re good.
I would be surprised if yours is still alive after that many heat cycles though.

[StarBear]

You should check yours. Manual says put a multimeter on it below 68F and confirmation tone/continuity. If you get the beep, then you’re good.
I would be surprised if yours is still alive after that many heat cycles though.

A good cold Sunday garage task. Will report. Thanks!

[StarBear]

You should check yours. Manual says put a multimeter on it below 68F and confirmation tone/continuity. If you get the beep, then you’re good.
I would be surprised if yours is still alive after that many heat cycles though.

A good cold Sunday garage task. Will report. Thanks!

@Van My analyzer does have a continuity setting so used a mood light. Pulled connector wire and went from timer spade to wire. No light. Does ignition need to be on/running? Not the sharpest knife in this sort of drawer…..

[Van B]

No. You just need to touch both prongs on the switch itself.

[StarBear]

No. You just need to touch both prongs on the switch itself.

@Van Oh, think I tested the wrong thing. Check the wiring diagram on Haynes page 177. It’s located UNDER the cold start valve which I must remove first (or just the blue CSV connector?)? I tested a sensor with a green/brown wire, near CSV next to distributor.