‘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.

[wonkipop]

i just did a cool start.
its about 4.5 hours later.

i get about 1 minute of slightly wobbly idle around the 800-850 mark.
then its settles at 850 for about another minute and rises to 950 steady.

@emerygt350 - yeah, i've always had a strong suspicion its the AAV when it comes to mine.

i know it works or it worked and i think it still does based on this morning. but not like its meant to new. i fully cleaned and tested it 2 years ago.
i'm pretty sure it closed from fridge cold in about 2 minutes. somewhere in my notes i wrote it down.

stone cold test start that i bothered to actually time this morning seems to point to AAV working for 2 minutes. the first 2 minutes it was running steady but at a very low idle.

then went into a strange phase for minute 2 to minute 3 - thats telling me something.
i think it wanted air but couldn't get it.

a few posts back i speculated my AAV is closing too fast.
its a wonder the one i have has lasted as long as it has.
being laid up for 15 years probably helped it get to here.

i'm not going to do your hose pull test on the decel valve.

i'm going to do a different one when i get time out at the shop when i take the car there for some other things i want to do.
i will unbolt the AAV then but leave it plumbed up and do a start where i just pull that hose off and test it all that way. also i think there is an AAV lying around off another porsche and one off something else out at the shop i can rig into the plumbing just to see what different aavs do at start up. do all my tests at same time.

i can't find anything in manuals that tell us how long the AAV is meant to take from full open to full closed. but from what i did this morning i believe it should be something around the 5 minute mark? if i can find enough AAVs lying around that i can sub in i might come up with something more than is it just not working at all.