Date:         Tue, 6 Sep 94 15:16:27 PDT
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         macklow@sybase.com (Jim Macklow)
Subject:      Re: Hesitation at low RPM

Hello,

> 
> On Thu, 25 Aug 94 14:45:03 CDT Jim Macklow said:
> >My '87 Syncro still has the following problem:  ...
> >For the FI experts out there:  Is this an indication that my computer
> >is/has gone bad?  Or is there some sensor that the computer ignores
> >in the first 30-60 seconds that is bad?
> >This behavior is fairly consistent, whether the engine is cold or
> >warm.  I seem to have a longer reprieve from the low-power demon on
> >cool, cloudy mornings.
> 
> i'd bet on the coolant temp sensor. just replace it. don't check it. mine
> all tested 'good'. finally, when i got disgusted and started just replacing
> parts, when i replaced it, the problem was 'solved'. i still don't know why
> it does that, but it has done it twice.
> 
> it could also be the oxygen sensor.
> 
> the way the behavior of the engine was explained to me was that if the
> computer gets confused by null readings or out-of-whack readings from any
> of its sensors, it (the computer) goes into Limp-Home mode, which doesn't
> give you much power, but it keeps the car running.
> 

I decided to check to see if I was going into Limp Mode, so I disconnected
my coolant temp sensor.  There was no change, still had hesitation at
low rpms.

Then I reconnected the coolant sensor, and disconnected the O2 sensor.
Bingo!  Without the O2 sensor attached, I have lots of power at all rpms,
and no degradation when the car is warmed up.  On the downside, it seems
to my very subjective eye which is looking at the gas guage, that my
mpg has gone to hell.  Like, maybe I'm getting 15, but probably less.
Lots o power, though.

Is this "evidence" that the O2 sensor is bad?  Should I ground the loose
wire instead? (maybe the van goes into "drink till ya drop" mode when it
gets 0 volts from the O2 sensor?)

Got any idears?

-Jim
macklow@sybase.com