78SC ROW Idle Adjustment ? ? ? (after Green wire from hell replacement)
 

Well, I finally got the green wire from hell (dist signal pulse) installed properly. I took her out for a < 1 mile drive and it would die at every stop if the idle dropped.

She will start fine and run strong at idle for 2-3 minutes. Then idle drops very low, sputters and she dies.

Question: I want to increase my idle speed - which way do I turn the screw pictured to INCREASE idle?

http://forums.pelicanparts.com/uploa...1157244679.jpg

counter-clockwise to raise idle

Thank you again JW - going out to try. Thanks for all the help with the GREEN wire from hell.

Tom

Tried it again. Engine was just below normal operating temp from my previous run.

Turned it in very small increments, probably 1/4th of a full turn counter-clockwise.

Idle did INCREASE a small amount..

Ran for about 2 minutes, then idle steadily dropped, and would increase a bit, then drop, then increase a bit.

Then it DIES.

Any ideas?

WUR?

Matt -- I thought of the WUR - but the symptoms don't fit. From a cold start, it now runs at a higher idle (because I adjusted it so) but after it's warm, same sympotoms persist.

Runs for 1-2 minutes, idle will then drop, then increase, drop, then increase, then dies.

I'm stumped.

I'm wondering could I have an problem with mixture?

Auxillary Air Regulator is not closing. Once the engine is warm the AAR should be closed.

I'm going to check now.

idle speed too low, idle mixture way too rich (surging) or way too lean (tends to die), or timing retarded, which slows the idle speed. one or all of the above, and maybe other things like intake air leak, dead hole, etc.

Like John said, it sounds like surging.
Try setting the mixture with the 3mm Allen key.
Carefully turn ccw (Lean) a very small amount. If it runs smoother, keep going until it sputters. Then go back cw (Rich) a small amount until it sputters again.
The correct mixture-setting is inbetween this two points.
Set the RPM with the idle speed screw.
Check your timing with a timing light.
Setting timing, mixture and idle speed should get you a good result. Play with it and see.

Having the same type of issues with my car. Idles fast when cold, then when hot I get alot of surging or loping. I have identified 3 leaking seals (air) around the injectors. They don't leak when everything is cold, but once everything gets warm they start leaking. The reason the car is idling fast when cold is because I have adjusted the idle speed when it is hot trying to get it to idle properly-well when it is cold everything is sealed like it should be so it idles fast because I have tried to compensate for the air leaks when hot. If you will spray starter fluid or some sort of cleaner on the injectors and the intake runners I bet you will find that you have some vacuum leaks as well. Take heart, I think you are getting closer to a solution. (I'm just waiting on parts for mine now and I should be up and running as well.)

Chris

UPDATE: I think it is my Aux air valve. Is AAV also called the WUR Matt? I think I got the two confused.

Here's what happens again:

Cold start, works great - idle normal - run for 3-4 minutes, then idle will drop -- surge a bit then drop, surge a bit then drop lower.

SURGE A BIT THEN DROP LOWER TILL IT DIES.

(takes about 30 seconds from when the surging high, drops start before it dies)

So I went to my AAV - felt quite hot. It should be CLOSED when engine is warm right?

Well, I powered down, did a disconnect on the AAV (from the intake line side) and plugged a capped socket into the opening.

Waited about 15 minutes for it to cool down.

[Started, ran great, perfect idle and did not ever surge or die. Took it around the block, ran perfect even at stops and in neutral at stops.]

With engine running, I pulled off the capped socket....

SAME SYMPTOMS - surge bit then lower, surge, then lower idle then DEAD!

I think I have a bad AAV valve! ! !

Anybody have one for sale for a 78SC ROW?


(thanks to all who helped with the diagnosis)

Let me ask - what is the harm of leaving the AAV end capped until I get a new AAV?

What is the best way to clean an AAV?

acapella: Are you confusing the AAV with the AAR?
AAR's are basically the same for all SC's.
Do a search and you'll find details on the AAR: How to clean and test.
I suggest that you get yourself a Bentley SC Repair Manual so you can understand the CIS and learn about the AAV, AAR, WUR, Decel. Valve, Mix adjust, Idle speed adjust, etc..........
You are asking questions that have been covered many times; lot's of info if you search here.
Get the Bentley, you'll love it! :)

I don't think you can clean an AAV. AAV has a diaphram in it that is held open by a spring to allow additional air into the engine when the engine is cold. Vacuum closes the the diaphram once the engine has warmed up.

Leaving the AAV cap will just cause a hard starting problem when the engine is cold.

Tom, you wanna borrow my Bently? I'm living in the city now, sans 911 so I wont be needing it for a while. Plus my dad's got a 3.2 one that I could always wing a project with.

EDIT: I might add I feel for you, im very lucky not to have had to deal with WUR/AAV problems on my car. They sound like a PITA.

If I remember, your car ran well before the GREEN wire problem, true? Then you had a large backfire, and the popoff valve blew off. This is where I would start looking. What else broke? AAR, AAV, a simple hose? I have seen airboxes split even with a popoff valve. The box bolts together and can lose its seal very easily. I think you are on the right path. I would make it a little easier by getting a spray can and look for leaks. You may find many! Be carfull not to get a false test by the vapor getting pulled into the air cleaner inlet. Also is the popoff valve leaking? I wish that I was local, it would make this quick work to solve.

Tom

just wondering is car working now?

I think the AAV broke -- after I removed the AAV and plugged the hose ends, the car ran great. It doesn't quite get the "breath" of air upon starup, but there are no leaks (no big ones any way)

and thus far, it's been running fine.

the initial start is a bit abrupt -- which is why I posted the WTB ad tonight in the classifieds for a replacement AAV.

Thanks to all for the much help recieved!

-Tom
(Matt thanks for Bentley offer, but I bought one. :) Now just because I have one doesn't mean I've comprehended all CIS logic..making baby steps here with CIS understanding)