9 5 ´02 2.0 cranks but won´t start when hot

[IceSaab]

Hello you all good people.

Have been searching for this problem on saabnet and here and google but without results.

When cold the engine starts right away and runs without problems. If I stop and turn the engine off it will not start again until it has cooled down. This takes around 1 to 2 hours.

My patience is not big so when I forget this and turn engine of to pump fuel, I can pour cold water on the engine and after about 30 liters it starts and runs.


Is there anyone that knows this problem? Or maybe the solution?



Best wishes, Jón Gunnar

[twoturbos]

Hi
You don't say whether the car is auto or manual but..............

Crank sensor (CPS) is the most likely cause (manual or auto).

If the car is an auto and , when you say it doesn't start you mean it doesn't even spin over it could be the Neutral Safety Switch (NSS). This is essentially the inhibitor switch to prevent an auto starting in any gear other than P or D. It is situated below the battery.

Both scenarios are very common

Edit :-)
Actually rereading the title, you do say it cranks but doesn't start so CPS is the most likely from what you have described.

[first-saab]

I second that, CPS. Should be replaced every 75 K mile imo. At 165K miles I am on the 3rd.

[IceSaab]

Hello and thank you for your reply, my car is an automatic and starts and runs fine when cold and I can drive it until the fuel runs out if I do not turn it off. If I turn it off though it will not start although it cranks and the fuel pump runs fine.


Best wishes, Jón Gunnar

[first-saab]

My experience with a bad cps was different, the engine would die when hot, then start up fine after cooling down.

[IceSaab]

After more testing and driving I find out that sometimes while driving normally in 90 km/h something happens and the motor acts like it looses power for a very short time (less than half a second I would guess). This has happened about 8 times in the last 4 days and 350 km. The check engine lamp is now lighting.

Also now while testing the car starting and letting it cool down again, happens 2 times that the engine stops while idling.

Mesuring the resistance of the CPS helps also, there is no conductivity when hot but when it cools down it has resistance of under 1k ohm.

My guess is the T7 does not need the signal from the CPS while running although it has to be connected.


Thanks, Jón Gunnar

[TankTak]

Originally Posted by IceSaab

My guess is the T7 does not need the signal from the CPS while running although it has to be connected.


Thanks, Jón Gunnar

Replace it as its job is to to monitor the position or rotational speed of the crankshaft. The information is then used by the ecu to control ignition timing and other engine parameters.

[IceSaab]

I will of course replace the CPS as I have now figured out that it is faulty. My guess was that the T7 did not need the CPS while running the engine when it has the signal from the DI casette. I´m guessing this cause the engine runs o.k. and when I turn off the engine it will not start again. I measure the CPS and it is faulty. Then when the engine has cooled down it starts and runs again.

Best wishes, Jón Gunnar

[IceSaab]

Hello, if someone comes across this tread in the future searching for answers then I can tell you that it was the crank position sensor. Just replace and away you drive.

Best wishes, Jón Gunnar