Date: Thu, 12 Aug 2010 14:20:18 -0700
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: AFM intermittancy result?
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reply-type=response
hey ..
if you are scoping AFM's I'll send you a few to play with perhaps.
dust ..
fwiw, I've seen this in Baja..
where I have driven in, no kidding, 3 foot deep fluffy flour-like dust.
Two to Three feet deep , like there's a large bow wave in front of the car
driving through it..
anyway ...
with a vw air-cooled engine and points igntion..
just a little bit of driving in that dust would cause the igntion to not
work.
the fix was to make a gasket for the distributor cap out of a plastic baggie
.
did that, and could drive in dust with no problems at all.
I am not convinced it's 'not' your AFM yet,
and I'm not saying that it is 'it' either.
we're waiting for YOU Rocket to give the final analysis and real fix !
fwiw,
just had a customer with an 84 Westy ...was loosing power on hills..
so I say drop it off ..
then customer says 'running fine now' ..but bringing it in anyway.
I drive it, seems ok .
I take a sample of the fuel...hmmm....kinda cloudly looking - a little
strange.
I remove the large later metal can type fuel filter - it was about 90 %
clogged.
then I removed the 'fire wall fire hazzard' thing, put in a bit of fresh
fuel, and a fuel treatment...
van sure seems to run better then before.
btw, that's a recommended upgrade for any 84 ( 83 to 85 ) vanagon or westy
..
install the larger later type ( 86 and up ) metal can fuel filter.
Obvisouly a better fuel filter..
vw does that ..
underbuilds, then upgrades as the go along.
that's so they could say '16 improvements for the new model year' .
it's better to remove the small square fuel filter ..
those are smallish, clog easier, and getting a little harder to find.
and I sure wish there was a full time fuel pressure inidcation in the
cockpit.
heck, some enterprising person could just make a simple pressure switch ..
much like an oil pressure switch............ if that light comes on in
flight ..
means fuel pressure isn't what it should be.
Scott
www.turbovans.com
----- Original Message -----
From: "Mike "Rocket J Squirrel"" <camping.elliott@gmail.com>
To: "Scott Daniel - Turbovans" <scottdaniel@turbovans.com>
Cc: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, August 12, 2010 1:53 PM
Subject: Re: AFM intermittancy result?
> Okay, so my van's 3 to 4 second loss of power would not have been due to a
> slight problem in the AFM.
>
> That said, I just opened it to inspect the track and found that the lid
> had come partially open sometime between now and the last time I had it
> open -- the RTV had let loose and quite a bit of dust had gotten inside. I
> blew it out and inspected it and the track appeared to be clean and
> undamaged. I applied voltage to the track and observed the voltage on an
> oscilloscope on the wiper as I moved it across its range and there were no
> dropouts.
>
> The dust /might/ have been fouling the contact during those climbs, but
> I'm not convinced that dust would cause such a consistent mode of failure
> 'cause dust gets pushed around.
>
> It baffles science.
>
> --
> Rocky J Squirrel
> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> 74 Westrailia: (Ladybug Trailer company, San Juan Capistrano, Calif.)
> Bend, OR
> KG6RCR
>
>
>
> Scott Daniel - Turbovans wrote:
>> on the one clear case I had of that ,
>> it was just a fifth of a second or so, just like someone shut off the key
>> for an instant, then back on.
>>
>> on my current 85 Adventurewagon .
>> it's stumbled a time or two after I drove it hour hours right at the same
>> rpm ..
>> right around 4,000 rpm jammin' down I-5 to get to Sacrameto before
>> businesses closed that evening.
>> - van ran fine on the way back in less of hurry.
>>
>> Then a week later in local freeway driving ...it 'stumbled' ..
>> like a large hiccup at speed ...probably the ARM worn on that one spot.
>>
>> I had another one ...it was 'weak' right at 3,000 to 3,200 rpm.
>> almost like a miss, and some people might not even notice it.
>> it was a stock syncro westy, and the way the gearing and torque curve
>> are, in normal driving around ...
>> just easy driving, you would be right about that rpm most of the time ...
>> we ended up doing a ton of things to that van ..
>> new driveshaft, rebuilt trans, new starter, new clutch , repair an engine
>> mounting stud in the engine case that had broken off ..with all that ...
>> it was easy to say what'a another 500 for a newAFM ..
>> and sure enough , that fixed it for that slight weakness at that one rpm.
>>
>> but more hiccups than large loss of power.
>> the only other thing I see AFM's do is run unevenly.
>> I'm gettting this 85 Westy GL all happy to sell, and I ran 6 differnt 1.9
>> AFM's on it , until I finally found one that's pretty even and smooth
>> through the whole rpm/afm flap position range.
>>
>> I always carry a spare AFM..
>> and ideally, we'd put a brand new one on every 50,000 miles or so.
>> a smooth running one with high miles on it is semi-rare to me.
>>
>> actually, I have never bothered, but I have thought about a NOID light or
>> equivilant up front that tells me when injectors are getting pulsed.
>> so you can monitor fuel shut off with closed throttle on deceleration ..
>> or if there is a stumble or glitch chopping the signal to the injectors,
>> you'd have a way to see that for sure.
>> and of course you have that with your 02 monitor system , though not
>> directly reading if injector pulse is happening or not.
>>
>> scott
>> www.turbovans.com
>>
>> Scott
>> www.turbovans.com
>> ----- Original Message ----- From: "Mike "Rocket J Squirrel""
>> <camping.elliott@GMAIL.COM>
>> To: <vanagon@GERRY.VANAGON.COM>
>> Sent: Thursday, August 12, 2010 7:07 AM
>> Subject: Re: AFM intermittancy result?
>>
>>
>>> So a small bad spot on the AFM track would cause the ECU to shut off the
>>> injectors, resulting in a full lean condition and immediate loss of
>>> power. When that happens, the AFM's wiper will swing to another part of
>>> the track, causing the ECU to start firing the injectors again, causing
>>> the engine to pick back up.
>>>
>>> I wonder how many seconds that process would take -- from "Hey, the
>>> wiper has lost contact with the track so I'm shutting off the
>>> injectors!" to "Oops, I see contact again and will start firing the
>>> injectors!"
>>>
>>> --
>>> Rocky J Squirrel
>>>
>>>
>>> Scott Daniel - Turbovans wrote:
>>>> I think that will cause the injectors to not be fired by the ecu.
>>>>
>>>> it won't affect fuel pump ....
>>>> since it will start and idle with no air flow meter at all,
>>>> or AFM unplugged.
>>>>
>>>> I'm guessing that if it's not at WOT or Idle ..
>>>> it depends on AFM contact to keep the injectors firing.
>>>>
>>>> ( ecu keeps fuel pump relay energized because it sees the engine
>>>> turning
>>>> from the ignition system. )
>>>>
>>>> Scott
>>>> turbovans.com
>>>>
>>>>
>>>> ----- Original Message ----- From: "Mike "Rocket J Squirrel""
>>>> <camping.elliott@GMAIL.COM>
>>>> To: <vanagon@GERRY.VANAGON.COM>
>>>> Sent: Wednesday, August 11, 2010 6:05 PM
>>>> Subject: AFM intermittancy result?
>>>>
>>>>
>>>>> What will the ECU tell the engine to do if the AFM's wiper loses
>>>>> contact
>>>>> with the track with the engine under high load condition, throttle
>>>>> depressed but not WOT (i.e., neither microswitch on the throttle
>>>>> assembly activated)?
>>>>>
>>>>> --
>>>>> Rocky J Squirrel
>>>>> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
>>>>> 74 Westrailia: (Ladybug Trailer company, San Juan Capistrano, Calif.)
>>>>> Bend, OR
>>>>> KG6RCR
>>>>
>>
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