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CIS Problem solved, maybe?

    As I had suspected for some time, the hose leading from a t-connnector
for the emissions carbon system to the intake manifold has a leak.  I
finally took the time to think and setup a proper testing sequence.
    Hooked up the multimeter to the DPR and started the 80.  I then placed
my hand undeneath the suspect hose and as usual I heard a woosh.  I then
clamped the hose at the furthest point I could from the intake manifold,
sound stayed the same.  I worked my way closer to the intake manifold and
the everytime the woosh got louder.  Also the closer to the intake manifold
I got the closer the engine came to stalling.  The closer I got the more
negative the DPR current got.  That means more air is entering the manifold,
the ECU is trying to compensate, right?
    This seems to make sense to my Bosch brain.  My normal DPR cycle is 0 to
5mA.  When I had the hose clamped closest to the intake manifold that caused
the leak to allow umetered air in.  Then that unmetered air passes through
the engine and the OXS notices that the exhaust contains too much oxygen and
"signals" the ECU.  Then the ECU sends a -5mA current to the DPR to richen
the mixture, compensating for the unmetered air.  That right OR am I not
thinking this through right?


Alexander van Gerbig
'88 Audi 80 -- Koni Yellows, G&M Springs
HÖR Technologies Sport Hydro Cam, K&N Filter
Borbet Type T, Dunlop SP9000 Sport

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