car runs great before it fully warms up...

Dizzy · Post by **Dizzy** » Mon Mar 29, 2004 4:17 pm

...but it seems to pull quite a bit less after it reaches normal operating temp. As I recall, the ECU operates in closed loop mode during warmup, relying on pre-set fuel/timing maps. Can anyone remember if that is the case?

Also, my idle is fine & boost peaks at the same value. (~11psi) It just feels like the ECU pulls timing. Any ideas?

Post by **Legacy777** » Mon Mar 29, 2004 5:23 pm

your getting more fuel when cold......coolant temp sensor.

This is one of the things the aftermarket chips do....alter coolant temp sensor readings to increase fuel delivery.

vrg3 · Post by **vrg3** » Mon Mar 29, 2004 6:18 pm

You're pushing full boost before the engine warms up?! That's probably not great for its longevity...

Many people notice a little more power when the engine's cold than when it's warmed up. I think part of it has to do with ignition timing being more advanced in addition to the richer fuel mixture.

ciper · Post by **ciper** » Mon Mar 29, 2004 7:29 pm

If the coolant temp sensor doenst help Id say oxygen sensor.

Dizzy · Post by **Dizzy** » Mon Mar 29, 2004 7:49 pm

You're pushing full boost before the engine warms up?! That's probably not great for its longevity...

The car is running on stock boost control mechanisms. I don't have a controller hooked up.

vrg3 · Post by **vrg3** » Mon Mar 29, 2004 7:51 pm

Yeah, but I don't think it's a good idea to actually drive the engine on boost (especially full boost) when it's cold. Before my engine warms up I usually stay off boost as much as possible and keep engine speed below 3000 rpm.

Post by **Legacy777** » Mon Mar 29, 2004 8:37 pm

I don't think you're going to hurt anything driving the car on boost before it's warmed up.

Sure you probably shouldn't redline it as soon as you turn it on and throw it into gear.....but making some boost shouldn't be a big deal at all.....

vrg3 · Post by **vrg3** » Mon Mar 29, 2004 8:44 pm

I was once told the cold oil wouldn't lubricate the turbo's bearings as well, so boosting when cold would shorten the turbo's life span.

bugeyes · Post by **bugeyes** » Wed Mar 31, 2004 3:52 pm

I try not to go under boost when its not warmed up but sometimes it just happens. Id be going up a hill at around 2.25k rpm (3rd) and be at ~7psi. I can hear the turbo spooling more when its cold (probably cause its not lubricated as well).

luckylouie · Post by **luckylouie** » Wed Apr 07, 2004 4:51 am

I just got a 92 L Wagon AWD 5MT NA but it came without a owner's manual. So my question is how long Subaru suggests to wait until the car is warmed up?

vrg3 · Post by **vrg3** » Wed Apr 07, 2004 4:54 am

The coolant temperature gauge should give you some idea of how warmed up the engine is. When the needle's about horizontal you're pretty good.

NICO · Post by **NICO** » Wed Apr 07, 2004 6:51 am

you what vrg3 my temp gauge does not go past half way, its stays in the middle of half way, i think it has some thing to do with getting ride of the a/c rad. before the change half all the time some times over, now under the half mark. i can drive right in the hottes day of the year and still red line every gear and it wont move past the half of half mark. what you think is it good like that for the motor.

vrg3 · Post by **vrg3** » Wed Apr 07, 2004 3:56 pm

Well, ideally, your coolant temperatures shouldn't change much when you change small parts of the system -- the temperature is still regulated by the thermostat, after all. So the difference in temperature you see ought to be just the change in how much heat goes into the coolant from the engine on its way from the water pump to the water manifold where the sensor is. I don't really understand cooling systems as well as I wish I did, so I can't say for sure whether it's better for it to read slightly warmer or slightly colder with the same thermostat.

DOA · Post by **DOA** » Wed Apr 07, 2004 8:11 pm

Most engines produce more power when the engine is cooler as the intake air is cooler and denser (especially true on turbo cars) and due to the thermodynamics of the engine (which I dont understand at all well) more power can be made by running the engine cooler, its just not quite as good for reliability hence higher running temps. It also sounds like the ECU adds extra fuel as well which with more air can only be good.
Its not a brilliant idea to thrash an engine from cold but hey, everything wears out eventually so why worry so much. Its far more damaging to thrash the car and then just switch it off by the way, warped housings and impellers, fried oil sticking the rotor shafts and so on.

NICO · Post by **NICO** » Thu Apr 08, 2004 6:23 am

very true

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car runs great before it fully warms up...

car runs great before it fully warms up...