theiceman

Yeah that's what I thought about that input but I wanted to double check to be sure .. there was nothing connected to that port.

Droops83

Thanks Pete. I have never seen that passage totally plugged up, but filled with enough carbon to make a difference in the idle mixture. But, re-reading Draco's posts, he said he has taken the mixture screw all the way out, and it didn't make a difference, so a slightly clogged passage probably wouldn't affect it THAT much anyway . . . . good to think about someone else's problem, as I spent most of the day trying in vain to get a crappy '76 912E that had been sitting 10 years to pass smog . . . . . pretty frustrating.

It's good that you checked for vacuum leaks since they can be a problem, but a vacuum leak will always cause a LEAN condition, so that wouldn't possibly be your problem anyway.

Also, whoever mentioned that checking O2s voltage with a multimeter doesn't tell you much is mostly correct. If you have a really good Fluke with the Min/Max/Avg voltage feature, this will give you a clue what is going on. You really need an oscilliscope to get the full picture. But you are supposed to check O2 sensor voltage while the sensor is connected, using a pierce probe or something similar.

I think that by "VFM" someone was probably referring to the airflow meter. The L-jet flapper-type airflow meter these cars use is sometimes called a "vane-type" airflow meter. Or they accidentally typed V instead of A. In any case, I think that this person was suggesting peeling back the rubber boot on the connector of the airflow meter and checking voltage at the pins while the engine is running, which is a good idea. You don't have to remove the airflow meter to check voltage(while running)/resistance(not running, connector disconnected), you just have to know which pin is which and compare it to specs.

Good luck!

Lorenfb

On the subject of AFMs, many mis-diagnose numerous problems and assume that
the AFM is the source. Actually, the AFM is a very reliable fuel injection system
component, especially when one considers its failure rate compared to the
later MAF (mass air flow) sensor (major problems) used on the later cars (993/996).
It's not uncommon to see cars with over 200K miles with the original AFM.

AFM problems occur when some attempt to re-position the internal resistive
wiper that rides on the thick film substrate, as recommended on the "dark side"
by some. All that's really required for long term maintenance, is some oil at
the pivot point of the "flapper" and some light lubricant on the thick film substrate.

With a CO meter, one can easily adjust the off idle (2000 RPMs) mixture by
varying the tension of the spring on the "flapper". This is set at about 1.0-1.5%
CO with the O2 sensor disconnected. The adjustment screw only affects the
idle mixture. It's not a good idea to adjust the AFM by its voltage output as
has been suggested on the "dark side".

The factory settings of the AFM were based on a number of fuel injection system
variables, i.e. the injectors used, the fuel pressure, the DME chip mappings,
and engine parameters. Change any of these, and the AFM no longer provides
the proper air flow data for the DME ECM. The resulting AFRs are no longer
set near the optimum for torque.

DRACO A5OG

Well it appears the culprit is my Air Flow Meter (AFM or MAF).

Check Connectors = Good
Checked OHMs = 1.89, Good

Voltage Check with a 9 Volt Battery reading 8.88 on DVM

Here are the results:

OHMs: 1.89K = Good

0.56: Barn Door Closed/or at rest
1.20: Slowly Opened to first mark on the potensioner
2.46: 2nd mark
3.67: almost 3rd mark then
6.07: for a split second then
4.17 - 5.34 until right before the last mark then
7.23: for a split second then
2.18: fully open Barn Door.

I think something is wrong with my AFM. Someone said I should use an analog meter but the 944 guy used a DVM too and he stated he got 0.50 volts at rest and gradual and steady rise in voltage until full throttle 8 volts.

I wanted to verify this so I was fooling around with the arm and got it to read 4.23 volts at rest and slowly moved the arm and it rose steady and gradually and managed to go 8.83 volts at full throttle/open barn door. I think the Sfernice 8404 Potensioner is bad.

I got nervous so I put it back. Test Drove and yeap same thing, rich at 0.82 volts at O2Sensor disconnected.

theiceman

sounds like a bad contact on the stat, can you rebuild it ?

DRACO A5OG

I am sure I could, but it is almost impossible to find the Sfernice 8404 Potensioner. Would you happen to know where I can find it?

A Pelican is willing to sell me his 40K AFM to me for $150. At least that will get me another 35K miles before an adjustment.

Damn, I am thinking if it is true my AFM is faulty. My baby has undiscovered performance gains. Am I thinking correctly on this?

theiceman

sure at least another 1000 horses

not sure where you can get a pot
Loren may know

http://www.clubelec.com/en/stock.asp...ng=1&x=10&y=11

DRACO A5OG

Heck I will be happy with 100 more horses or just what she supposed to have, 207-220???

Checked there no 8404's

Hey Loren, can you help?

TIA,

theiceman

i figured you may be able to call them and they might be able to do a compatibility check

DRACO A5OG

Yeah, I e-mailed them, they are French, my French is pretty bad, I can only Curse and ask where the bathroom is. Or like a good American ask for a Coke with alot of Ice. Coke avec Boqu Glase, Si Vue Ple

theiceman

and i can't even french kiss damn it

DRACO A5OG

You Crazy, LOL

It's too messy anyways, well at least I am. Oops "TMI"

Hey Loren, pretty please???

DRACO A5OG

So could one deduce that this could be the reason she is running rich and why the A/F adjustment screw is all they way out to near falling out.

I imagine with the improper position of the barn door due to faulty signal output/input, it restricts air causing the mixture to go rich and then my poor O2 Sensor working like a 2 bit ***** to lean her out resulting in the lowering of the RPM's at idle.

DRACO A5OG

Update: Clubelec does not carry the 8404 Fsernice Potensioner.

I have a 40K AFM on its way from a Pelican in Texas. Will bench test to verify condition.

Per Loren's Website:

0 degrees = 0.25 volts & 4.5 volts = 110 degrees (WOT) DVM but it conflicts with the 944 Guy's readings on a known good AFM and another Pelican that verified 0.50 at 0 degrees and WOT at 8.5 volts.

But this makes some sense, if Loren based his readings from the AFM connect to the DME which only emits 5 volts to the AFM, then his readings confirm a bench test with a 9 volt source. Is my simple deduction correct?

rusnak

I think that's a good assumption.

I took my afm off for giggles today and found it's doing something similar to yours! I measured both resistance and output voltage. Voltage climbed steadily then about half way open started to drop.

So, now I'm thinking about either cutting off the black plastic cap and going for it, or buying a rebuilt one. I think if I can find one for less than $500 then I'll go that route.