Lizard928

Are you sure you adjusted it the correct direction?

I would suggest swapping your barn door with one in another car and see if it follows your barn door.
I have seen a few of these barn door have dead spots in the chip which will cause exactly what you're describing.

granprixweiss928

Yep I'm sure it went the right way. Pretty obvious which way is looser.

Regarding trying another...I have another and it makes no difference. My car is only 59k miles so I doubt worn contacts are really the issue.

granprixweiss928

Anyone have a new green wire that I could do a test with to see if that helps.

Mine is original as far as I can tell, brown in some spots but no visible cracks or issues in the wire.

granprixweiss928

just tested fuel delivery rate and pressure and all is good there, well in Spec.

Mrmerlin

if you have an original green wire then invest in a new one.
NOTE the green wire is most often the cause of poor running conditions,
over time the insulation cracks and then corrosion starts inside the wire, you cant see it.

The only way to rule it out of the poor running condition,
is to install a new one.
based on your info its time for this to happen

granprixweiss928

Green wire on order.....

RKD in OKC

On AFMs...had a 76 914 and it would randomly stumble while cruizing. Took it several mechanics and no-one could fix it. Frustrated I removed the AFM and cleaned the copper on the tps potentiometer part with a pencil eraser. The curved copper the arm travels on in picture 44. It never stumbled or cut out again.

granprixweiss928

pulled distro and tested vacuum pot and reset timing, and replaced green wire - and no change or improvement.

starting to think the temp sensor 2 or the little vacuum sensor on the head by Cyl 4. the temp sensor tests out ok.

The car has also started a slight looping idle during warm up- its not quick looping...and not when cold, and not when hot. only in between in the middle.

The symptom described in this thread and what Im trying to solve happens when hot or cold.

granprixweiss928

I also about a week ago tested Fuel flow rate and pressure. Everything was in spec. I'm ruling out fuel delivery problems.

granprixweiss928

update, I still have my issue.

I returned the spring in the AFM back to the original position and it runs and starts better now. at its 10 notch tighter, it was harder to start.

on warm up from a cold engine the car, the idle was at 1K until it starts to drop. it did a little up/down for awhile but then it settles at about 750 once warm and stays there. I tightened all my hoses and that improved it somewhat, as all hoses were new and have since swelled abit.

I also went thru my whole vacuum system from the brake booster take off, checking all the hvac pots and the vacuum reservoir, the cruise control, and heater valve. all is good there.

my next test is to check that the 02 sensor is functioning and install a new coolant temp sensor.

The Fixer

This is good advise, your 928 may only have 57K miles but it's still an old car as you know. It is real tough with older cars that you can't simply plug in an get a code.

New vehicles you can pull a big vacuum line off and the computer will compensate at no one would even notice.

I just bought a very low mile vehicle (1990 MY) w poor running issues probably from sitting..and the last issue i dealt with (hunting idle) was exactly what you describe.

I went through everything even checking engine compression. It was very good and very even.

Turned out that the TPS (throttle position sensor) i diagnosed as bad and that i replaced with a "new" one was sticking and not returning as it should when i let off the throttle. It was real bad at times and at times not. high idle, then low, then hunting, etc.. Really irritating.

I suspected the new TPS, checked it with the multi-meter but it was fine.

So i removed the throttle body (again) and looked at the TPS closely removed from it and it was sticking (not returning always)

So if I were you I would suspect your AFM at this point. But they are expensive and not something to replace without solid evidence that it's bad.
You can test it with a multi meter.

If you haven't already cleaned their contacts as RDK suggested, i would.

I would also be sure the entire intake manifold is torqued down right and sealing along with the throttle body/air guide housing.. I see you have checked and replacing any suspect vacuum lines.

If you've got good fuel press it's seems either electronic in nature or a decent vacuum leak. Or both.

Your AFM could be telling your computer that your foot is here but your sitting with your foot off the pedal. Which was my issue.

I'm sure you've checked the pertinent grounds already.

Sometimes even low mile cars have compression issues though, especially complex V8s. There can be manufacturing issues with any marquee.
I hope not but I have seen it a lot with V8s.
Bad compression can cause hunting. I highly doubt it with your car though. Does your car run cool?

Anyway in my recent situation my ECU was being told one thing (on throttle) from the TPS and the butterflies were somewhere else (closed), thus causing the hunting at idle.
Another new and slightly more expensive TPS from the dealer and it runs perfect now.

The Fixer

I'd like to see an engine compression test done.

granprixweiss928

I did a compression check before i started this thread, and all cyl were around 180 psi except one i think, which was around 175. Done with warm engine, throttle plate open durring cranking.

The Fixer

That's terrific.

You need someone with a known good AFM to let you swap it in.

If you cannot find anyone close and want to pay shipment you can try mine.

(it's ported and polished so don't try the old switcheroo)

granprixweiss928

I have another afm that I already tried with same results. It has unknown mileage but it tested electrically within spec per the WSM.

starting to think its mechanical...

Mark