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

[Van B]

Ok fellas, here’s the run down Aux Air Regulator (AAR) and Cold Start Valve (CSV)/injector both work fine. Many of you have also been keeping up with my high idle issue that we figured out.

But yet, when the car is cold, i.e. room temp, I don’t get the high idle I should on start-up. Instead she cranks a bit and then lumbers to life. Idle lopes around 700-800rpm and then smooths out as it warms.

In all other aspects of operation, the engine seems to be pretty happy.

Thoughts? Experience? (IMG:style_emoticons/default/confused24.gif)

-Van

See post #419 on page 14 for a synopsis of the outcome.

[Van B]

So, I pulled the CSV/injector today and put some tape over the manifold. Kept the CSV connected and cranked the engine. It gave a nice cooling gasoline spritz all over the engine while I was cranking the engine, but once the car started, it was content with the work accomplished and went to sleep.
So, if that’s all it’s meant to do, it’s doing a great job. But if it was supposed to do more, something is telling it not to.

Van

[wonkipop]

So, I pulled the CSV/injector today and put some tape over the manifold. Kept the CSV connected and cranked the engine. It gave a nice cooling gasoline spritz all over the engine while I was cranking the engine, but once the car started, it was content with the work accomplished and went to sleep.
So, if that’s all it’s meant to do, it’s doing a great job. But if it was supposed to do more, something is telling it not to.

Van

sounds about right.

a couple of years ago when i was recommissioning mine the engine would run for around 5-10 seconds or so on the cold start valve alone. did not have a stop watch on it. the injectors despite reconditioning were kaput, but she would start and run off the cold start valve for a short time.

that was around the end of autumn (you call it fall). temps in workshop would have been about 15C or 60F in USA temp. the cold start definitely kicks in above 50F as others state is some kind of on/off cut off.

i was down at the workshop today working on the falcon ute so i asked mike, who is the mechanic looking after all our cars. i went over the cold idle thing with him.
my car is all set up properly tuned off the analyzer when the engine was fully warm with the correct fuel/air mix. his view is that the AAV is probably inhibiting fast cold idle.
basically they get old. they just have a sprung steel coil in them that heats with electrical current. after 50 years of cycling the thermo coil spring degrades etc. they just don't work like they did when new. the coil weakens. which means that they close a bit quicker than they are supposed to, or close enevenly or even stick and then suddenly close.

we tested mine a couple of years ago and it appeared to open and it appeared to close.
did the fridge test and then hooked it up to a battery. but its not like i timed it against any data. my memory was that it closed reasonably fast, maybe in 2 minutes or so.
which might be too fast?

anyway, i don't worry about it too much. i know the engine is set up nice with air fuel mix when its warmed up to operating temp.

i really can't shed any light on the problem other than to suspect the AAV might be not behaving as it would have 50 years ago, which is how i look at mine.

i've got a feeling it idled more strongly from cold start when i first recommissioned 2 years ago and lately its been a little weaker for the first minute or 2 of operation.
could be my imagination. if i get time i might take another look at the AAV and electrical connection. probably at christmas.