What does this mean?

[2ndwind]

My 82 FI car has had idling issues since day one. I replaced the auxiliary air valve and nothing. Mark graciously had the same valve rebuilt again because we thought the opening through it seemed awfully small. Apparently in 70-80 degree weather it is supposed to be a small slit because it came back re-rebuilt with the same small slit of an opening.

Upon initial start up, the car starts fine and most of the time will idle fine for 20-40 seconds. If I don't drive it right away, the idle drops to 250-300 then often to zero. Once the engine warms to about 140-150 degrees or more it will idle fine all day. After the engine is hot and idling fine, if I go into a store and return within a few minutes, it starts fine but drops its idle this time within 2-4 seconds. If I let it run for 20-30 seconds it will struggle at 250-300 RPM then all of a sudden within a few seconds it picks up to about 500 then 700 then 850-900 and I'm off to the races again. But sometimes it idles to low on the restart and dies.

The AFM is a $500 rebuilt one, temperature sensor has been replaced, and I set the idle according to Brad Artigue's procedure. Today I sprayed starting fluid around the relevant parts looking for a potential air intake leak. The only one I found was BEFORE the AFM where the top housing clips onto the lower housing that holds the (new) air filter. Does an air leak matter at that point? If not, what's up with my idle?

[radiopilot]

Don't fret I had the same problem, I bought a new AAV and installed it... same problem... the air intake boot had a small crack... resealed it with RTV... solved the problem for a week or so... the idle screw has a small o-ring that was not sealing correctly... replaced that and it worked like a champ... then it idled rough again... bought a new air intake boot and all problems went away... idling perfectly now... I'd say check the boot and idle screw o-ring... everything else is out of my league... perhaps others can chime in and I might learn something too.

Nick

[2ndwind]

Thanks Nick,
I put in a new lambda sensor yesterday because I didn't know how old it was or if it was the problem. It wasn't. I am running out of parts to replace. I took the intake boot off and inspected. There is a crack in the underside of the tube that goes to the AAR. One would think the inserted metal tube (to the AAR) and hose clamp would cover it but maybe not. The day before I found the idle screw all the way in. Re-evaluated today. It is extremely easy to turn, maybe needs a new o-ring too. More parts replacement.

[radiopilot]

This is the same location I had the split on the boot... I tried high temp RTV but it held for so long and still had the erratic idle... I bought an excellent boot from MatthewsParts and installed it and the problem went away.

The o-ring in the idle screw gets a flat spot after a while and looses the grip thereby allowing the screw to turn on it's own with vibration and possibly the vaccum from the plenum. I carry o-ring spares now in my toolbox now.

Nick

[2ndwind]

Nick,
I ordered another intake hose. Today the car has been more cooperative. I did RTV the crack and took the idle set screw all the way out and put it back in.

Where did you get your o-rings? I am concerned about getting ones that can tolerate the heat.

[radiopilot]

I got my o-rings at PepBoys in a metric pacakage that has the correct size ($6.95 for the package of hundreds of o-rings sizes)... I installed the one that would give me a very tight fit. I oiled it just enough to slide in without binding with MMO... worked perfectly and these o-rings are now like I said earlier in my car tool kit for emergencies.

There were others suggesting using a 'goo' type glue and that may work as the RTV did but eventually it will continue to crack and have more leaks as my boot did... best is to pick up a decent uncracked boot or a new one.

Nick

[2ndwind]

Thanks Nick,
There is a Pep Boys on one of my frequently-traveled routes. Interestingly, as mentioned above I have had no low-idle or stall issues for 2 days. BUT it is idling at 1500 rpm when up to temp. i am convinced the new boot and o-ring will allow me to set the idle properly. You've been a great help, enjoy the weekend.