Re: Multi-function sensor woes....

[Thomas Tornblom <Thomas.Tornblom@nexus.comm.se>]

> 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.

Thomas