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[tech]: idle specs on a 2.0L 16v cis-e?



so, jason (since you seem to be the only one reading this thread), you would 
agree that setting the duty cycle/bypass screw slightly lower than normal 
would be the solution? or at least on the low end of normal?
as for the ignition...i don't have my bentley with me, but i guess it 
doesn't really matter how it knows what the idle speed is... it has to do it 
somehow. i can think of indirect ways, but seems it would be easiest to 
measure it off the ignition somehow. btw, that wasn't what i meant about 
real knowledge-just a concrete answer instead of hypothesizing (though 
that's half the fun with these cars, i guess)
-michael

>>  that's how i understand it. the idle speed itself is not adjustable, per
>>bentley. the computer has the correct speed hardwired, and it's your job
>>to make everything right in order to get there. so it'll switch duty
>>cycle to make the idle speed right
>
>Right.  It's always going to try to idle at the same speed.
>
>>. and yes, it should still idle at the right speed, but your tolerences
>>would be less since the the computer is already working to correct for the
>>maladjusted bypass screw.
>
>Bingo.  If the correct idle speed has to be reached by a duty cycle outside
>the computer's ability; then idle gets messed up.  In this case, since the
>engine would be pulling more air, the aux air bypass would be letting more
>air in.  If the idle screw was closed too much for the aux idle valve to be
>able to compensate for it, the engine will idle too low.
>
>
>>  anyone with real knowledge want to weigh in on this one?
>
>Well, I do have "real" knowledge, technically, as I've read the Bosch fuel
>injection book from cover to cover.  The problem is that every iteration
>from different manufacturers have different sensors telling the computers
>different things.  Some deduce idle from a crankshaft position sensor (the
>CIS-E on my Mercedes, for example -- which also uses the sensor for a
>separate ignition computer that has 100% control over timing).
>
>The problem I have with our logic is that I don't know how our KE-Jetronic
>computer knows engine speed.  The hall sensor goes to the ignition
>computer, so that can't be it....  (unless it goes to both?)
>
>Jason
>
>
>
>
>>-michael
>>btw, my idle miraculously cured itself with the apparent end of winter
>>here in the ATL.
>>
>>>From: 16V Jason <jason@scirocco.org>
>>>
>>>Your thinking does make sense -- I think. :)
>>>Unfortunately I don't have my Bosch manual in front of me -- but lemme 
>>>ask
>>>everyone:  Is the idle speed adjusted by the duty cycle?  Or (if my
>>>understanding is correct), does the duty cycle just indicate whether the
>>>idle air bypass screw is adjusted properly?
>>>
>>>If I'm right, and the computer knows idle speed, and changes duty cycle 
>>>to
>>>keep it where it's supposed to be (but can only do it within certain 
>>>limits
>>>and therefore you have to check the duty cycle to see if the screw is in
>>>the right range), then Michael's right... the duty cycle would be higher
>>>than it was in the 1.8... which would mean that the idle adjustment screw
>>>should technically be adjusted to bring the duty cycle back down.  
>>>However,
>>>if the car still idles perfectly, then the idle screw is set to a value
>>>that is still within the aux air bypass's ability to stabilize it and
>>>therefore it's not 100% necessary to adjust anything.
>>>
>>>...or am i just nuts? :)
>>>
>>>Jason
>>
>>
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