Since I last posted with issues regarding low fuel mileage, a miss on the A bank and a bouncing idle I have done the following:
· Replaced vacuum advance
· New plugs -gapped at .025, ones I took out were at .035 (new ones were .035 out of the box, pays to check)
· New plug wires
· Cleaned breather cap filter
· Changed the module within the Ignition Amplifier.
Also checked that the rotor moves and returns as it is supposed to.

The good news is that it runs much better and I learned a lot. No more miss on the A bank. The idle is still giving me issues. At first it went to 1250 rpm until it warmed up and then it started hunting for the idle, bouncing between 700ish and 1250. The higher rpm was noticeable while I was driving and kept bouncing in park and neutral when I stopped.

I let it sit, came back and started it again and it went to 1250 and then started hunting. I opened the left air filter housing and blocked off the flow to the AAV. The idle didn’t drop on several tries, but there was no more bouncing after that. In park and neutral rpm was 1250, in gear with my foot on the break it was just under 1000. I took it for a short drive and this didn’t change. Moving or stopped, 1250 in neutral and 1250 in park and just under 1000 in gear but stopped.

Any ideas? No obvious vacuum leaks, but then again what is obvious in there?

Any help is appreciated.

 

Does the idle speed repsond to the adjustment screw on the AAV?

Also, make sure your throttle blades at set to .002" clearance, the throttle bores clean, and the throttle linages adjusted.

Don't leave the AAV plugged for long. You'll suck oil up thru the distributor and soak the inside of your dist cap.

Cheers
DD

 

I haven't moved the adjustment screw because until the last run the idle was bouncing. Is there something that would through off the adjustment? Prior to the idle swings it had been resting at 750 when warm.

I only plugged the AAV long enough to see if idle was impacted, but I appreciate the advice as I didn't know that could happen.

I'll check the other items you mention.

Thanks for the help.

 

If the engine doesn't respond to adjusting the AAV screw then it suggests that incoming air from elsewhere is overpowering the adjustment.

Cheers
DD

 

Upon further review... Oops. I was covering the wrong hole. Took another look in better light and the idle drops significantly with the correct hole covered. AAV is pulled and I'll follow other posts/The Book and see how I do.

 

I am having the exact issue! When cold at start up it idles at about 1000rpm and then when it warms up it idles at 1200 rpm and every few seconds will briefly sag to 700 and return up. It is extremely annoying when I am coasting because the car decelerates whenever it surges! I just had replaced spark plug wires, coil, ignition amp, distributor pickup, and cap.

 

Agreeing with ALL said, but whilst you are in there check the TPS voltage at idle.

Since you have "The Book" it is in there.

If that is too high (0.32v - 0.36v) the ECU will be confused as to what fueling signal to supply for stable idle.

The cross rods as Doug mentioned are CRITICAL for all sorts, and idle is one of the main ones. Again "The Book" has a very detailed procedure for this, and as said in there, THERE IS NO SHORT CUT TO THIS ADJUSTMENT.

 

Much better now. I pulled the AAV and soaked it in a spray of penetrating oil overnight. A #10 3 inch wood screw fits into the holes in the shaft and allows the spring to be worked up and down. I also tapped the top down a few millimeters. I'm at about 850-900 now, so I'll adjust downward with the screw.

That part didn't take too long, but waiting for the replacement hose from the AAV did. Unfortunately the old one was baked on and split coming off. Getting the new one on was big fun.

Grant - Thanks for the advice. I think I will follow-up with that as well. I also noticed some bushings missing that I want to replace.

I appreciate all the help.