Mongo

I wouldn't rule out an O2 sensor yet since replacing it may cure some of the running problems.

Do you have an ohm meter also? It wouldn't hurt to test your throttle position switch either. A failing TPS can do some very interesting things to a car. Considering the fact that your car falls flat at idle when depressing gas a little bit or no throttle response, I would definitely check out that TPS.

DarkGrey

I've been using my multimeter non-stop with this problem. Part of what makes this mystery so deep is that all the electrical checks out 100%!

The last time I lost all throttle response my AFS tab wasnt making contact with the carbon strip but that sure isnt the issue this time :s

Mongo

Is there anyone you know that you can swap air flow meters with?

DarkGrey

I have a second AFM here that I've tried. Both check out fine with the multimeter. UGH!

DarylJ

OK...so let's back up. How did this all start? How was it running before?

Lets try to eliminate some other issues, like bad gas, clogged fuel filters (yeah....I hear ya, FP is fine, but you know what I'm getting at).

Mongo

If FP is fine I'm thinking it's vacuum. Could be the auxiliary air valve failing.

DarkGrey

Gas is yesterday fresh, fuel filter is 2months old.

If it was vacuum, wouldnt the car idle a little higher then usual?

Mongo

Yes and no. I had a cracked intake boot that caused a vacuum leak. I would get a weak idle in the morning but a high idle on a warm start due to unmetered air.

When an auxiliary air regulator goes out, the mechanicals stick or fail partially closed, open, etc. causing an uneven idle and hard starts when warm.

DarkGrey

Ok so maybe you can fill me in on this burning question I have:

How exactly does the AA Regulator work? (I have an '86 car so its an Idle Stabilizer Valve.) I have it out of the car right now for cleaning. Out of curiosity, I plugged it into its spot in the wiring harness and layed it on top of the manifold.

With the key in the ON position this little motor hums away happily. I looked inside and saw what appears to be a little gate that either swivels all the way around or moves up and down. I cant tell because all it does is vibrate in its spot lol

How much should the internals be moving? Is it only supposed to vibrate??

Mongo

To give a little insight on the 944's Bosch L Jetronic:

http://www.forparts.com/techbosLjetronic.htm

The auxiliary air regulator ( also known as auxiliary air valve , idle stabilizer valve, idle regulator ) is the device that allows air to bypass the throttle body and enter the engine to give a stabilized air fuel ratio at idle. The device is electronically monitored by the 944's DME. The valve is an electrically heted metal valve that opens when the motor is first turned on. When the engine warms on, a bimetallic valve is heated by an electric element slowly closing off the air bypass, decreasing the amount of air entering the motor. This in turn will reduce the idle speed.

In the event of failure, sometimes this valve will not close and cause more air to enter the engine. Consequences will result in stalling and erratic idle due to an unbalanced air/fuel ratio.

However, what makes me suspicious of the TPS is the characteristics you had described when you depress the gas after a warm start. This makes me rule out the air regulator. Part of me does believe that it is either or... You an actually get a used TPS just to test it and see how your car reacts. No throttle position switch lasts forever and it will eventually require replacing. Your car may have hit that interval.

Mongo

I am not sure about the vibration of the internals though. Usually if something is working mechanically, it will move and progress smoothly. Be suspicious of it...

In all honesty, I really think you should change that oxygen sensor also. Bosch sells a Universal 3-wire that can be spliced into the system. The part number is # 15726 and it can be spliced into your existing O2 sensors wiring harness. PM me if you want more details on how to do this.