Difficult cold start

Wouter1973 · Post by **Wouter1973** » Thu Apr 28, 2005 9:14 am

Hi! My '92 Legacy 2.0 GL (no AWD) is not starting as smooth as it should. That is: when cold, I turn the key, engine drops and almost stalls, the check oil on my dash lights up, then it revs to about 1500 rpm, drops again and allmost stalls, and finally starts running smooth, about 1200 rpm slowly dropping to 750 rpm as the engine warms up. I looked for vacuum leaks, couldn't find anything suspicious. The engine starts smoothly when warm.
Anyone an idea what this could be?

Post by **Legacy777** » Thu Apr 28, 2005 2:40 pm

check the codes. More then likely the coolant temp sensor needs to be replaced.

Wouter1973 · Post by **Wouter1973** » Thu Apr 28, 2005 2:42 pm

And I can find this coolant temp sensor where? Sorry to tell you that I'm not that streetwise onder my hood, is it the same as MAF sensor?

Post by **Legacy777** » Thu Apr 28, 2005 2:52 pm

No, the maf sensor is completely different.

The coolant sensor measures the coolant temps. It can be located under the intake manifold

http://www.main.experiencetherave.com:8 ... P_2477.JPG

It's the bigger one in that pic.

Wouter1973 · Post by **Wouter1973** » Thu Apr 28, 2005 2:55 pm

Now I see....thanx! In the Netherlands that part is called 'themostat'...

Wouter1973 · Post by **Wouter1973** » Thu Apr 28, 2005 3:00 pm

Let me get this straight....is it possible that my problem (which is basically a rough start when cold) is caused by this coolant sensor? Correct me if I'm wrong, but if this sensor is broken my engine would become too hot, or wouldn't get hot at all, right? I'm asking this, because the temp of the coolant water seems to be right when the engine has warmed up, according to the meter on my dash...

Post by **Legacy777** » Thu Apr 28, 2005 6:11 pm

You have things confused.

That sensor is the coolant temp sensor, not the thermostat. All the coolant temp sensor does is measure the temperature of the coolant, and send that information back to the ECU.

Depending on the temperature of the coolant, the ECU will adjust the air/fuel mixture to help the car start better when it's "cold". It also turns on the radiator fans when the temp reaches a certain point (200 deg F).

The coolant temp sensor is kind of finicky. Sometimes they can just sort of break, or just not work worth a shit. What you're probably experiencing is the coolant temp sensor telling the ECU that the coolant is already warm. So the ECU isn't giving the engine enough fuel to start when "cold". It's just like a choke on a carburator.

The thermostat is a mechanical device that helps control the coolant temp, mainly the lower temp of the normal operating temperature range by closing slightly, and restricting flow to the radiator.

Make sense?

Wouter1973 · Post by **Wouter1973** » Fri Apr 29, 2005 7:00 am

Ok, this makes sense to me. Your explanation fits really well with what actually happens when I start the car when cold. So where can I find this coolant sensor? Is it hard to replace? I know w store here that sells 2nd hand Japanese car stuff, they probably have another sensor for me.

Post by **Legacy777** » Fri Apr 29, 2005 8:19 pm

the sensor is in the pic I posted above

this should help too
http://www.surrealmirage.com/subaru/fil ... tion10.jpg

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Difficult cold start

Difficult cold start