"Return-to zero shock absorber" missing...

[Willoughby Z]

Some background:

I had a recent "event" where the engine shot nearly to WOT at turn of the key (without using accelerator pedal). I shut down the engine, restarted and the car ran like cr*p. Low,rough idle. Missing,poor throttle response. Exhaust smoke like a crop duster. I was only a few miles from home, so I gambled and drove it home, bucking and complaining the whole way.

Next day, long story short, I discovered the vane in the AFM was stuck in full open. Touched it and it closed by it's spring power. Cleaned it carefully and it seemed to operate smoothly over the range of movement but it would occasionally stick at the full open position. I put everything back together, installed fresh plugs and cap/rotor. The car has been starting well, running smooth and strong.

Today, while replacing the idler pulley/ belts/water pump and fan clutch, I removed the AFM- for better clearance and access.

Having read practically everything on this site with regard to the EFI system, I thought it might be a good idea to remove the black plastic cover of the AFM and do a visual check while it's on the bench, of the internal components and reseal the cover. I had a copy of the AtlanticZ AFM write-up and I discovered that watch spring coil or "return-to-zero shock absorber" is missing and the tab mount is bent. After I took photos, I also realized that part of the bracket for the spring is missing-the "keeper" or "stop", if you will.

It looks as if a PO or even a reman. tech may have tried to repair the broken bracket with an epoxy.

[ see photos]

I assume all components are there for a reason, some for better reasons than others. I am thinkinking of a way to fix it. Haven't come up with an idea, perhaps a rubber bumber to soften the return of the counterweight. Open to any thoughts on the problem.

Thanks for reading.

[Willoughby Z]

BTW, the second photo is from the AFM worksheet ( for reference)

The yellow arrow in my photo points to the gray blob of epoxy(?) and the red arrow points to the tab (no spring) which is bent downward.

The AFM looks otherwise, pristine and unmolested. Obviously, someone's been in it but there is no evidence of repairs/tampering/adjustments.

[esmit208]

I would get the entire unit replaced. A replacement part has a warranty and this is an

infrequent issue. Replacing it now will mean that you won't ever have to replace it again in your time of ownership. Besides it will give you piece of mind. Vibration and heat will cause any self-fix with electronic components to fail not to mention moisture.

[Willoughby Z]

esmit208:

Appreciate your thoughts. So you're saying that a mechanical fix, like substituting for the return spring absorber to protect the counter-weight wouldn't be worth the effort?

It's not the adjuster spring or anything electronic. I intend to reseal the cover against dirt/ moisture.

I thinking that other than the broken bracket which is only necessary to bring the counter-weight to a "soft" stop the AFM is working perfectly. I fear introducing new issues with a reman unit, more than what I have. I hear you on the warranty issue and the mean-time-to-failure life of a new(er) part.

[FastWoman]

I don't think that shock absorber is that critical an item, but I could be wrong.

I recently realized you can completely disassemble the AFM using the screws on the waffle side of the AFM. The screws appear as little bumps, liberally covered in some sort of adhesive. You can loosen/remove the adhesive with carb cleaner or paint thinner. I've never had reason to take the thing apart, so I can't attest what would happen -- whether there are any exploding parts or such. From what I can tell, it appears the vane hangs on a couple of bearings pressed into the main body.

[Willoughby Z]

Thanks FastWoman.

There are two screws at the bottom of the box- covered as you described. I used solvent (carefully) to disolve the glue, also removed the collar and gaskets so as to be able to tap the plate outward from the inside.

There are no exploding parts. I took photos that I will upload later.

I found the source of the sticking (previously posted). The corners of the vane were overtraveling in the chamber, jamming at full travel there were shiny spots as a clue. I thought about deburring them but I gently took some of the arc out of the end of the vane- a tiny bit. Seems counter-intuitive but when looking at the shape of the vane and where it was rubbing, that seemed to be the answer. And it worked. Having the plate off and the innards exposed, allowed for a thorough cleaning, particularly the backfire valve, which was corroded enough to stick badly.

With the plate off, I decided to re-create a post for a spring/bumper, working from the inside. I drilled a small hole from the electronics side, countersunk from the chamber side, so that a small diameter flush head screw wouldn't interfere with the edge of the vane during it's travel. Washer, locking nut,finished. Cleaned plate, box edge, reassembled with silicone...

Searching my "MacGyver" box, I found a hi-temp silicone rubber sleeve that fit tightly over the portruding bolt, allowing for a "soft stop" against the shoulder of the counterweight. Sealed plastic cover and re-installed AFM.

Lo and behold, it started!

FWIW, replacing the fan clutch really quieted things down and raised my operating temperature by 10 deg (by dash gauge). Replacing a nearly seized idler piulley with the NAPA 38038 groove pulley cut out some racket that I apparently gotten used to..

One last thing, I don't know how every other fan shroud is assembled, but the two halves (upper/lower)of mine were attached to each other by three screws and threaded clips-screw heads facing down. before re-installing, I reversed the clips, placing them on the lower shroud so the screws face up.

End of debriefing.

[FastWoman]

Outstanding!

I look forward to seeing photos!