Date:         Tue, 5 Dec 1995 08:56:44 CST6CDT
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "Dan Houg" <fairwind@northernnet.com>
Subject:      wasserboxer tune-up report, part 1

Stage 1 is done.  results of Stage 1 tune-up necessitates a Stage 2.

Prior to this most recent tune-up i had 2 complaints (well, on the 
van i mean):  an erratic idle, especially when cold and a very 
pronounced cold start miss accompanied by puffs of black smoke.

the tune-up included:
switch from NGK to Bosch 3-prong W7DTC
remove and clean throttle body of carbon
scrub up throttle switches of grime
reset basic throttle plate setting and throttle switch
air filter
oil change
fiddle with CO adjustment
clean idle stabilizer with carb cleaner
replace ECU water temp sensor

the Results:
the warm and cold idle is rock steady now.
the cold idle miss still partially remains but is subjectively cut in 
half.  drivability is excellent but really was good prior to work.

Observations: taking voltage reading off the O2 sensor, i see my open
loop (sensor disconnected, crankcase breather blocked) voltage is
high, about 0.9v equating with a rich mixture.  i could not get this
lower by turning the CO screw, well appreciable lower anyway.  with
the sensor connected, the readings alternated on both sides of 0.5v
so the mixture regulation is functioning in closed loop.  one
important point on the open loop readings... i forgot to pinch off
the carbon canister hose to the air box.  *maybe* that continually
spiked my open loop reading high but i have my doubts because they
remained high at all RPMs.  

Conclusions:
i think my next step to lower the open loop sensor voltage will be to 
increase air flow meter spring tension a notch.  i am currently 
"Techron-ing" the van in case an injector is bleeding fuel but again 
i don't expect it to be this.  i'm wondering if the flapper spring on 
the air flow meters slowly looses some of its tension over time and 
needs to be brought back in line.  

i also have some false air leaks at the rubber+fabric manifold 
connectors to the intake runners.  more than likely we all do.  on my 
'85 i replaced all the crimp on clamps with #24 hose clamps and that 
solved that problem.  i have the 8 #24s but havent put them on.  
however, false air leaks would lower the O2 sensor voltage in open 
loop mode so this is an unrelated problem.

if anyone has ideas on why my open loop mixture is so rich, please 
speculate away.

-dan