SaabCentral Forums banner

1 - 5 of 5 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
My 9-3 Convertible just started something odd. After driving it, then trying to start it again within 15-30 minutes, it won't start. It will crank without any problem, telling me there's no battery problem, but it won't fire at all. Then after a short break, I go back out there and it starts right away. It started doing this late last week. Thinking it might be an old fuel filter, I replaced that, but tonight same problem. My daughter was driving it, made a couple of stops, turning the engine off, then restarting without problem. Then, on her last stop, no go. I went back about an hour later, and it started the first time.

This problem did start right after filling an almost empty gas tank, so maybe the fuel pump picked up some junk in the bottom of the tank, or I got some bad gas. I refilled it tonight at the half full mark, drove it about ten miles, but had the same problem when I returned. I going to give the new gas a chance, but I don't really think this is the problem, since it either starts fine or doesn't start at all (though I have noticed an occasional miss since trying to solve this).

Anyone had a similar problem or have any ideas? I'll likely be taking it to my Saab mechanic early next week, but I'd like to be able to suggest to him what it could be.

Thanks.

JM
 

·
Registered
Joined
·
4,293 Posts
That is one of the two possible symptoms of a failing crankshaft position sensor.

When the sensor starts to fail while driving, the engine may miss or stall, and there may be a CEL and a corresponding fault code.

When the sensor fails during a start attempt with engine hot, there is no signal to the ECU at all, and therefore there is no CEL and fault code generated. The ECU uses the signal to determine the engine is cranking (and later, rpm and crankshaft angular position, tdc, etc.) Once the engine cools off, the sensor generates a valid signal, and the engine starts.

With no signal from the CPS, the ECU will not start the fuel pump (no fuel pressure), or the ignition (no spark).

Edit: oops, looks like a duplicate thread.

http://www.saabcentral.com/forums/showthread.php?p=1112856
 

·
Registered
Joined
·
7,876 Posts
jm7128 said:
My 9-3 Convertible just started something odd. After driving it, then trying to start it again within 15-30 minutes, it won't start. It will crank without any problem, telling me there's no battery problem, but it won't fire at all. Then after a short break, I go back out there and it starts right away. It started doing this late last week. Thinking it might be an old fuel filter, I replaced that, but tonight same problem. My daughter was driving it, made a couple of stops, turning the engine off, then restarting without problem. Then, on her last stop, no go. I went back about an hour later, and it started the first time.

This problem did start right after filling an almost empty gas tank, so maybe the fuel pump picked up some junk in the bottom of the tank, or I got some bad gas. I refilled it tonight at the half full mark, drove it about ten miles, but had the same problem when I returned. I going to give the new gas a chance, but I don't really think this is the problem, since it either starts fine or doesn't start at all (though I have noticed an occasional miss since trying to solve this).

Anyone had a similar problem or have any ideas? I'll likely be taking it to my Saab mechanic early next week, but I'd like to be able to suggest to him what it could be.

Thanks.

JM
2 possible problems. PMI indicated the first ie a bad CPS.
It's best to test it on a warm engine, not cold. The resistance values should be 860+-100 Ohms IIRC but I'm not 100% sure of that so do your homework first.

The second is the purge valve. Unplug it and see if the car goes back to normal. The check engine light will light up obviously since an emission component is unplugged. No harm to the car though. :cheesy:
 

·
Registered
Joined
·
2,203 Posts
hkayssi said:
2 possible problems. PMI indicated the first ie a bad CPS.
It's best to test it on a warm engine, not cold. The resistance values should be 860+-100 Ohms IIRC but I'm not 100% sure of that so do your homework first.

The second is the purge valve. Unplug it and see if the car goes back to normal. The check engine light will light up obviously since an emission component is unplugged. No harm to the car though. :cheesy:
Where is the purge valve located?
 

·
Registered
Joined
·
4,293 Posts
mr rx-7 tt said:
Where is the purge valve located?
On the NG900 it is located on a rubber hanger below a metal bracket, on the passenger side strut tower. You can also find it by simply following the evap canister purge hose back from the throttle body.
 
1 - 5 of 5 Posts
Top