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Re: Multi-function sensor woes....

> Date: Mon, 26 Sep 94 16:38:00 EDT
> From: cordeiro@adi.com (Alan Cordeiro)
> Reply-To: quattro@swiss.ans.net
> X-Charset: LATIN1
> X-Char-Esc: 29
> >Oh, and one other thing,  lately my car has been stumbling pretty
> >bad when cold.  I was poking around looking for vacuum leaks when
> >I brushed against the oil dipstick.  It was pretty loose in the 
> >tube.  So I pulled it out, and there are 3 or 4 grooves in the
> >top plastic piece but only one groove had a little rubber donut
> >on it.  Are they all supposed to have rubber donuts on them ?
> >If the answer is yes I hate to think they went into to the
> >engine......Yikes!  Guess I'll do that oil change tonight...... 
> >In any event I fixed it by taking an old Fuel Injector seal
> >rubber donut and putting it at the top of the dipstick plastic insert.
> >Worked like magic!!  You can now start the car and immediately back
> >out of the driveway and accelerate away without any stumbling whatsoever.
> >So if you having any cold stumbling problems.  check that dipstick!!
> >Mike (hoping the rubber donuts are caught in the filter...) L.
> Hi Mike,
> What am I missing ?  How did tightening up your dipstick in the tube
> cure the stumbling problem ?
> The only change you could have made was seal up any vacuum leaks into
> the engine compartment, but there should be a pretty good path into the
> crankcase from the pipe that feeds fresh air into the PCV system.
> I was wondering if you had figured out any explanation.
> Alan ( will check, but does'nt recall having any donuts ) Cordeiro.
>  P.S. does'nt have any stumbling problems either.

The problem with leakage through the dipstick tube (and all other
vacuum leakages) is that this air is not measured, and thus the engine
will get a lean mixture. The PCV system takes measured fresh air, and
the mixture will be correct.

This is very simple to check, just pull the dipstick a bit with the
engine idling and you should notice a distinct change in RPM.