Saab: Saab 93 Turns over but doesnt start, rich fuel mixture, dirt accumulation

Question
QUESTION: Seems to happen only after driving for awhile. When I go inside a store, come
out, car turns over (not a battery problems but won't "ignite." Never happens
when starting cold, or first thing in the morning.  Help.


ANSWER: Lisa: I'm am sorry, but as stated, my hands-on experience does NOT include the 93. What I can say, in general, is that the problem is likely somewhere in the cold-starting circuit, probably due to a sensor failure. For example, if a temperature sensor failed and made the control computer "think" the engine were still cold, even though heated up, it would provide an overly rich fuel mixture which would result in your situation.
         A good mechanic ought to find the problem quite easily.
         Hope this helps.
         Jerry


---------- FOLLOW-UP ----------

QUESTION: Jerry, thank you; How would a mechanic diagnose this? Three people I've
brought the car to already shrug their shoulders adn say 'Oh it's the battery" or,
just on Friday, replaced something called a "cartridge" which didn't work.
Elsewhere I've readd "replace the starter solenoid" do you know what that is?

Answer
Lisa: Firstly: The starter solenoid is a switch that enables the starter to operate. Since you said that the starter works[ turns over], that is DEFINITELY not to blame!
Likewise, if the car starts well when cold and it turns over (but does NOT start) when hot, that says that the battery is in good working order! another 'bum' steer!
A mechanic would start out the diagnosis by attaching a code reader to the electronic test plug; this allows the control computer, which monitors just about 'everything', do be read out. If that doesn't reveal anything, then individual components need to be manually checked for function, for example on earlier model Saabs there is a cold start/automatic idle valve that , being mechanical, sometimes gets stuck due to dirt accumulation. As I'd stated, I cannot speak about the precise details of your system's components, but cars being similar, and Saabs being of conservative design suggest that the approach as above is applicable.
  Hopefully you will find a competent and honest mechanic somewhere.  BTW, in what city are you ?
         Jerry