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Discussion Starter · #1 ·
Problem started on Sunday night on the M4 at about 80mph. Felt like the engine was misfiring and very rough, when I accelerated I could see a cloud of smoke in my rear view mirror and the car ran OK for a while. I managed to get the car home (£40 of fuel Reading>London)and to my local garage on Monday. He found a few air leaks and has changed a vacuum hose and the hose that joins the air flow meter to the inlet manifold. The engine ran fine until it warmed up and the problem started again. Anyone got any ideas why it should run so rich only when the engine warms up? Need to get this sorted urgently as the purple clio with flowery seats he's let me use isn't doing much for my image, even if it's saving me loads on fuel bills!!. (93 9000 CS, non-turbo, a/c, no DI)
 

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If your engine temperature sensor has failed, the ECU may decide that it's cold and overfuel. Same thing as running with the choke out all the time. So, OK when cold because you need the "choke out" but when hot it stays rich.

Another guess I'm afraid but it's all I can think of at the moment.
 

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It's in the middle of the head, at the back of the engine, underneath the inlet manifold, near the AIC. It's a small screw in device with a 2-wire connector.

You can test it if you want to... search this site for info. Basically you need to test its resistance with a meter at various temperatures.

However, the first step is to check that the connection is good, so inspect the connector and clean it if needed.

You could also borrow and try a known good one if you can find one. You should only lose a tiny bit of coolant by removing it (on a cold engine;) )
 

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Here are the resistances for a working sensor:

20-30 K ohms at -30 deg C
7.0-11.4 K ohms at -10 deg C
2.1-2.9 K ohms at 20 deg C
1.0-1.3 K ohms at 40 deg C
0.565-0.670 K ohms at 60 deg C
0.295-0.365 K ohms at 80 deg C
0.24-0.26 K ohms at 90 deg C
0.14-0.16 K ohms at 110 deg C
 

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Discussion Starter · #8 ·
No luck with that, problem persists!!
Had a suggestion from a saab fiend in Bristol that it could be the flywheel sensor. Has anybody had any problems with this before or have any other ideas.
P.S. The car was running like s**t when it was started this afternoon, so the problem is intermitant rather than temp related.
 

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My 9-5 was stalling intermittently. Varying from once in a month to three times in a day.

I have changed the crankshaft position sensor. It stalled on the very first trip to check it out, but it's been fine since - over three months and 8,000 miles.

At around £60 it was a cheaper option to try than many others.
 
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