Engine cutting out

[satchmo]

If you can save that bad AFM until the next time I come through, I would like to see if we can resurrect it.

That would be a lot easier to answer if I knew when you were coming through next, but yes, I will hang on to it indefinitely.

Here is what the Fuel Injection Corp. reconditioned AFM looked like. I have no idea how many miles there are on the AFM since its rebuild, but there can't be too many since the bus has only 59,000 miles.



Here are a couple photos of the points:





I got the bus running with an older and dirtier AFM today. Seems to run okay, but I'd like a back-up before I take another trip. Also solved the mystery of my headlights, turn signals, etc. Just lots of corrosion in the fuse box up front. (Did I mention this bus had an electrical fire under the dash at some point in the past? I don't think I did. It makes for constant fun.).

Tim

[Amskeptic]

I will hang on to it indefinitely.
Here is what the Fuel Injection Corp. reconditioned AFM looked like. [/img]

Excellent. In the photograph of the AFM, I could not tell if that was just reflection or a worn track.
The wiper adjustment position looks wrong to me. Yes, after many years, I can see the typical adjustment position which is normally four teeth to the silver edge. This gives only a crescent beyond the hold down screw. Yours looks to be at 3 teeth and a big space beyond the hold down screw. Yours looks to be almost centered in the available slot. Totally too lean. However, it can be compensated for by loosening the black cog dramatically. Then you have too much transient swing which can give stumbles upon acceleration, lousy fuel mileage, etc. Ask SG Kent over on theSamba what the weight is to make the flap move. He did a write-up I believe. Don't actually adjust it, just check to see if the flap moves with less than specified weight (60 grams I think). If so, the adjustment scenario I just gave you may be the culprit here. Here's a BobD afm comparison of wiper position.

[satchmo]

And here is a shot of the AFM that was loaned to me so I could make it home:



So why is there so much more room to adjust the wiper to lean than there is to rich? And why didn't the factory leave any mark to indicate initial settings besides just the blob of silicone on the screw? It is difficult to determine how far off a used AFM might be from its original setting.

Tim

[Amskeptic]

So why is there so much more room to adjust the wiper to lean than there is to rich? And why didn't the factory leave any mark to indicate initial settings besides just the blob of silicone on the screw? It is difficult to determine how far off a used AFM might be from its original setting.

Tim

That looks much more typical. Typically, Bosch had to make these AFMs available to a whole host of cars with different maps. The matrix is loosely:
lean wiper rich cog = "x" variations from there . . .
rich wiper lean cog = "x" variations from there . . .

and the ECUs of all of our different cars would do the math between ignition pulse frequency/load position of the wiper. Our buses all seemed to have the rich wiper lean cog position, which actually makes sense. Air-cooled engines cool down so fast on overrun, I thought maybe they liked a lean blow torch overrun to keep the combustion chambers heated up.

Don't you wish we could find Heinz the Bosch/VW engineer and pick his brain before he passes on?
ColinIDo

[satchmo]

I checked my original (I mean the FIC rebuilt) AFM according to the testing procedure in the Bentley. Here is what I got:

1) Pins 36/39 - Flap closed: no continuity. Flap open: 28 ohms. Checks out fine.
2) Pins 6/9 - 310 ohms. Spec is 100 to 300 ohms on 76 and later models and 200 to 400 on 75, so it is close
3) Pins 7/8 - No continuity. Spec is 80-200 ohms. Fail.
4) Pins 6/27 - 2500 ohms. Spec is 2500 ohms. Check.

Pin 7 looks to be connected to the copper arm that reaches over the top of the wiper and there is good contact there. If I press the wiper contacts firmly onto the wiper board, I get some continuity, but none when I let go.

Colin, do you still want me to hang on to this AFM, or should I send it in to FIC and have them take a look at it for their own QC purposes?

Tim

[Amskeptic]

I checked my original (I mean the FIC rebuilt) AFM according to the testing procedure in the Bentley. Here is what I got:

1) Pins 36/39 - Flap closed: no continuity. Flap open: 28 ohms. Checks out fine.
2) Pins 6/9 - 310 ohms. Spec is 100 to 300 ohms on 76 and later models and 200 to 400 on 75, so it is close
3) Pins 7/8 - No continuity. Spec is 80-200 ohms. Fail.
4) Pins 6/27 - 2500 ohms. Spec is 2500 ohms. Check.

Pin 7 looks to be connected to the copper arm that reaches over the top of the wiper and there is good contact there. If I press the wiper contacts firmly onto the wiper board, I get some continuity, but none when I let go.

Colin, do you still want me to hang on to this AFM, or should I send it in to FIC and have them take a look at it for their own QC purposes?

Tim

Totally up to you . . . 7/8 can easily be fixed by removing the wiper and adding a little dogleg bend to the copper contacts and adding a little height to the copper contact that sprouts upwards to meet the center copper thingamahicky.

These things are pretty simple/easy so long as there is not a ripped up board or blast-damaged flap/chamber.
Colin

[satchmo]

7/8 can easily be fixed by removing the wiper and adding a little dogleg bend to the copper contacts and adding a little height to the copper contact that sprouts upwards to meet the center copper thingamahicky.

These things are pretty simple/easy so long as there is not a ripped up board or blast-damaged flap/chamber.
Colin

Already tried that maneuver way back at the mechanic's place in Petaluma, then tried it here with the multi-meter to check. No help. The tracks are pretty worn through on the board - that is not a reflection in the photo. The flap/chamber and body of the AFM look nearly new.

Center copper thingamahicky? What happened to our ideal of being specific with our language and parts naming?

Anyway, I think I have that noisy metal thingy in the trunk just about all runnin' good with the replacement box that has a wire plug in it and is hooked to that other big black box and to a big black accordion hose. I just move those big screw things around and back and forth until it sounds like it is purring and smelling sweet at the pipe. Car moves along now okay and when I step on the black plate on the floor it kinda goes except when it doesn't or when I push with my foot on one of those pedals. One pedal makes it coast and the other seems to make it stop real quick. Is this what is known as a coaster brake?

Tim

[Westy78]

Interesting, I think those were the pins that tested way out of spec on my FIC rebuilt AFM too. I chased that problem for months and never suspected the AFM since it was "rebuilt".

[satchmo]

Interesting, I think those were the pins that tested way out of spec on my FIC rebuilt AFM too. I chased that problem for months and never suspected the AFM since it was "rebuilt".

Well, it is nice to know I'm not alone. I'd be curious to see what FIC has to say if I sent it in to them.

My used one is working great so far. I haven't taken the bus out much yet, but I'm considering going to Buses By the Bridge in Lake Havasu City next week, with a little side trip on the way to Joshua Tree. We'll see. This trip I'm taking every spare part I have.

Tim

[SlowLane]

I'd be curious to see what FIC has to say if I sent it in to them.

Probably something like this: "You don't have a receipt and the top has been opened up. Our warranty is void. We'll gladly sell you a new one."

Now, GoWesty has come up with an interesting alternative. I was actually musing about the possibility of doing this myself, but someone beat me to it. Of course, it carries a typically hefty GoWesty price tag.

[Amskeptic]

I'd be curious to see what FIC has to say if I sent it in to them.

Probably something like this: "You don't have a receipt and the top has been opened up. Our warranty is void. We'll gladly sell you a new one."

Now, GoWesty has some up with an interesting alternative. I was actually musing about the possibility of doing this myself, but someone beat me to it. Of course, it carries a typically hefty GoWesty price tag.

Fricken prices! I understand, I understand, but geeze.

I would like to see if we can restore function to your AFM, as a hack exercise in getting the most out of the parts we have. In my experience thus far, I have never left someone's house with a "bad AFM" diagnosis, ever. never.
Colin

[satchmo]

I'd be curious to see what FIC has to say if I sent it in to them.

Probably something like this: "You don't have a receipt and the top has been opened up. Our warranty is void. We'll gladly sell you a new one."

Now, GoWesty has come up with an interesting alternative. I was actually musing about the possibility of doing this myself, but someone beat me to it. Of course, it carries a typically hefty GoWesty price tag.

Are you saying there was a warranty? Ha, ha, not likely at this point. I was trying to frame this in the best possible light thinking that the FIC quality control folks might actually care to see what happens to one of their refurbished units. This AFM does have an FIC number on it (see first photo). So even though I don't know when this unit was purchased/installed, they might. And perhaps they would actually care. It's a family run business, isn't it?

I had read about the GoWesty solution(s) a while ago. It seems unnecessarily complex and expensive when one can still get a used/rebuilt AFM (or in the case of Vanagons, a new one). Not to mention the fact that one completely gives up the option to revert back to stock because GoWesty requires you to send in your original FI system! That pretty much meets the definition of "We have you by the balls!"

I'll hang on to this AFM for Colin since he is truly interested in seeing if he can make it functional.

Tim

[dingo]

I like the idea of using hot wire AMM instead..cant be that difficult...whats the out put signal look like? how is it different from the
flipper ?

[satchmo]

I like the idea of using hot wire AMM instead..cant be that difficult...whats the out put signal look like? how is it different from the
flipper ?

Did you read this: http://www.gowesty.com/library_article.php?id=805

And follow up with this: http://www.gowesty.com/library_article.php?id=1532

I think those should answer your questions.

Tim

[SlowLane]

I like the idea of using hot wire AMM instead..cant be that difficult...whats the out put signal look like? how is it different from the
flipper ?

Did you read this: http://www.gowesty.com/library_article.php?id=805

And follow up with this: http://www.gowesty.com/library_article.php?id=1532

I think those should answer your questions.

Than follow it up with this one: http://www.splitsec.com/technotes/AFM_t ... ersion.pdf
Split Second are the makers of the AFM replacement GoWesty was/is offering.
In a nutshell, the MAF sensor doesn't have the range of output (0-5V) that our ancient AFMs do (0-9V-ish), not to mention a different response curve. The Split Second solution is a digital one, and while I'm all for microprocessors where they make sense, I think in this case an analog solution would give smoother results. I only wish I had the analog background to design the circuit.