Re: ECU/Oxygen sensor question

["Doyt W. Echelberger" <Doyt@nwonline.net>]

>To: Richard J Lebens <rick-l@rocketmail.com>
>From: "Doyt W. Echelberger" <Doyt@nwonline.net>
>Subject: Re: ECU/Oxygen sensor question
>
>I just drove a car of exactly same model and equipment and year as yours.
It was up for sale. At 187k miles, it had the driving characteristics you
indicated.
>
>As part of the test drive, I put a dollar bill up against the end of the
exhaust pipe at idle, and it got sucked in and blown back out so fast it
sounded like a machine gun.  To me, this points toward one or more exhaust
valves that aren't sealing on the intake stroke.
>
>I could feel the uneven power flow by placing my hand on the stick shift
lever during straight and level driving at various speeds. The unevenness
was being transmitted through the gearbox and I could feel it in the stick.
>
>My guess was that the car needed at least a valve job. I $u$pected other
problem$ in the head region but the dollar bill te$t convinced me that at
lea$t the exhaust$t valve$ weren't $ealing, and that'$  bad new$
mechanically and financially.
>
>I asked the owner about maintenance and tune ups.  The reply indicated the
car was given $400 in tune up service a month ago, during which the oxygen
sensor was tested and found  OK. My conclusion was that the mechanic tried
everything he could think of to eliminate the surging, failed, and now the
owner is selling the car.
>
>I am probably taking the car to an Audi mechanic Monday to confirm my
suspicions. Have no idea what a valve job costs on a 20 valve, but a
thousand-plus dollars seems like a good ballpark and probably involves new
valve springs, guides, seals and new exhaust valves. Maybe the cams are
going bad, and it should get new lifters while it is apart.
>
>Do the dollar bill test and tell me what you find.
>
>Doyt Echelberger
>87 5kcstq
>
>>>>>>>>>>>>>>>>>>>>>>>>>>.
>At 11:00 AM 12/10/1999 -0800, you wrote:
>>
>>If an injector were clogged would the ECU/Oxygen sensor be able to
>>compensate for the excess oxygen and not set a fault code?  How would
>>this condition (clogged injector)be diagnosed?  They all seem to be
>>clicking away.  Would an exhaust gas anylizer show anything?
>>
>>Has anyone had their injectors cleaned/inspected as routine maintenace
>>and how much did it cost?
>>
>>
>>Still troubleshooting this:
>>
>>1991 Audi 90 Quattro 20 Valve
>>
>>I have been experiencing surging under light load in 2nd or 3rd gear
>>under
>>light throttle.  While cruising it feels like the engine is cutting out
>>momentarily, kind of like when the AC is on (which it isn't).  I
>>replaced
>>the oxygen sensor and now I no longer have a hunting idle after coming
>>to a
>>stop but the surging is still there.  The idle also isn't as smooth as
>>it
>>was a couple weeks ago.  I searched for vacuum leaks with propane and
>>found
>>nothing.  Techron didn't work.  Plugs are new.
>>
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