Re: low idle/stall when first starting

[Aleksander Mierzwa <alex@matrix.com.pl>]

At 13:29 23.04.98 -0400, Preston Brown wrote:

>I've been having ongoing trouble with my 86 5000CST for the last couple of
>months.  It is NOT related to the idle stabilizer valve, which is only
>about 6 months old and has just been cleaned.  My oxygen sensor was just
>replaced as well.
>When the car is first started, the idle is really low, and it will often
>stall.  You have to stay on the gas.  After about 10 minutes of driving,
>it will idle and not stall, but the idle is still "borderline" I.e. I can
>see it bouncing down almost to the point where I think it might stall
>every couple of seconds.

Preston, I can think of couple of things.
First of all, a large vacuum leak will usually cause low idle. It may be
worthwile to visually check the condition of all vacuum hoses. 
There's a separate temp sensor for the idle stabilization system. It's the
one-point sensor on top of the upper coolant flange. The specs for this
sensor are about 1000 ohms at 20C and about 100 ohms at 80C. This sensor is
identical to the ECU sensor mounted on side of the head under the flange,
so a quick and dirty method to check the operation of both sensors is to
swap the wires between them and see if it makes any difference.
Finally, don't overlook the obvious - is the idle switch working properly? 
If everything turns out to be withit specs, you may want to simply adjust
the idle screw. 


Aleksander Mierzwa
Warsaw, Poland
mailto:alex@matrix.com.pl
87 Audi 5000CS turbo (mine)
88 Renault Medallion wagon (mom's)
91 mountain bike (just in case both cars broke at the same time :-)