Saab 9-3 Turbo Convertable starting problems

[saaby]

I am having problems with my Saab in as much as it starts OK...I run it for 3-4 miles, stop and it won't start again for 30 or so minutes, then it coughs and starts again. It is turning over but just wont fire up.  Whilst driving the 3-4 miles it also clunks after a mile or so but does not break down at this point.

It has been into the garage twice now and has had a new battery and coil pack but the garage (no being Saab specialists) haven't got a clue?

Any ideas?

[ScarbSaab]

Although I've not had it myself, hot start problems can be the Crankshaft Position Sensor (CPS). Have a search on this site (I'm pretty sure it's been covered on the 9-5) for info.

[sgould]

I agree.  The CPS is favourite.  About £60 for a new one.  It's a Bosch part supplied to Saab.

I have cured the same symptoms on two 9-5's so far, by changing the CPS.

You can do a check of the CPS resistance.  But it's not always conclusive, as a normal reading does not mean it's OK.  Whereas a reading outside the limits is a good indication of failure.

The CPS is on the front of the engine block on the passenger side of the car.  It's awkward to change as the (hot!) exhaust is in the way.  But you check the resistance at the connector, which is at the end of a long wire, up behind the engine.  If you look under the air inlet pipe behind the top of the engine, you should see a block of three connectors.  The one nearest the engine is blue.  Undo this and you will see three pins.  Only two of these will show a resistance across them.  Resistance should be between 770 ohms and 950 ohms at 20 deg C. Resistance changes a bit with temperature.  Most failures result in the resistance going over the 950 ohms.

Some attachments to show the CPS under its tin cover. And the connector.

[pandaboy]

I also agree with the CPS. 

My CPS went and the symptoms were similar, although I didn't have any 'clunking' like you describe. 
Basically mine would start up fine when cold, but once the engine was up to temperature it wouldn't restart until it had cooled down again.  I did once have to resort to dousing the area of the CPS with cold water to hasten the cooling process, but this is not recommended...!

As sgould says, its awkward to get to.  I found it fairly straightforward to remove, but putting the new one in was a little challenging...