On Fri, 10 Jan 1997, dan perdue wrote:

>  Will someone please help me. I am trying champion 302's (hotter plug) and
> it is o.k...
> Is there a way to adjust richness like cis-e injection in 80 Scirocco??
> I've fiddled with the screw near the air-box and noticed no real
> change...HELP

On modern cars the fuel injection is "set for life"; there's no idle or 
idle mixture adjustment feature at all.  The reason for this is that the 
O2 sensor and ECU monitor the engine at all times, adjusting things 
accordingly, so there's no reason to have these manual adjustment features.

Your '81 fuel injection is not that modern in that it allows you to 
adjust the idle and idle mixture but, in theory, there's no reason to do 
so since the O2 sensor and ECU are performing the same monitoring 
function.  So, before messing around with these things, check to see if 
some element of the fuel injection has failed, causing the rich running.  
A common failure is the #2 Temp sensor, located in the head above #3 
cylinder.  This can be easily checked with an ohm meter.  Likewise the #1 
Temp sensor can fail (not as common).  It too can be checked with an ohm 
meter.

What I'm saying is to check each element of the FI system out before 
adjusting idle and idle mixture.  If everyting checks out OK and it's 
still running rich, and if adjusting the screw in the air flow meter 
doesn't imporve things, then I'd suspect that the air flow meter itself 
is causing the problem.  There's a spring inside the air flow meter that 
resists the opening of the air vane inside the meter.  Over time this 
spring seems to lose strength, giving less resistence to air flow, which 
translates into the ECU setting a richer mixture than the engine really 
needs.

Although all the books say that the air flow meter is not user 
servicable, THEY LIE.  You can adjust the spring inside, fixing this 
problem.  The Vanagon archieves detail the adjustment; if you can't find 
it ask me and I'll tell you how.

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Tom Young               young@sherlock.SIMS.Berkeley.EDU
Lafayette, CA  94549    '81 Vanagon
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