Date: Thu, 12 Aug 2010 12:50:32 -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
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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