200 10V stumbles, poor mileage

LL - NY larrycleung at gmail.com
Sat Dec 19 16:36:15 PST 2009


Leaky injectors?  The have a service life, I just can't recall the miles.
Symptoms *also* include lengthy cold starts (cold system has leaked out all
pressure, so you end up cranking while pressure rebuilds) and if parked
indoors, a slight under hood smell of gasoline. Don't recall if the plugs
were wet when checked.

On Sat, Dec 19, 2009 at 1:52 PM, Konstantine Bogach <kbogach at comcast.net>wrote:

> Hi Huw,
> forgot to mention O2 sensor:  it is only one year old, maybe two.
> But... who knows, you are right, that would be an explanation.  I
> checked duty cycle and it sweeps around 50% - same as it was before the
> car started to stumble.   Would it be a proof of good oxygen sensor?
> Can I disconnect oxygen sensor connector when measuring?  Would using a
> scope give more definite test?
>
> Thanks a lot.
> Konstantine
>
>
> On 12/19/2009 05:49 PM, Huw Powell wrote:
> > A failed oxygen sensor could cause such symptoms.  Put a voltmeter on
> > its output at warm idle, while connected, and check what it's doing.
> >
> > Konstantine Bogach wrote:
> >> Hi all,
> >>
> >> my 200 MC2 stumbles at idle or when I increase RPM, until I am at
> >> 3000 rpm.  Above 3K I don't feel stumbling.  All plugs are same wet
> >> and black. Coil resistance,  CIS system and control pressure are
> >> within the spec.  Can not see a vacuum leak anywhere (also did carb
> >> cleaner spray test).  But I don't think it is a leak b/c at higher
> >> boost it runs better rather than worse.  Inspection of ignition
> >> distributor cap did not reveal a clue (I tried the spare one too.)
> >>   Almost not working in cars last 2 years I forgot what I had learnt
> >> before (mostly from this list).  What I should be looking next?  Can
> >> broken soldering in the throttle switch cause such symptoms ?  Hall
> >> sensor?  RPM or crank position sensor?  There is no codes stored.
> >>
> >> All ideas will be appreciated.
> >> Thank you.
> >> Konstantine
> >> 200 '91 & UrS4 '93.
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