Car has trouble starting when cold...

[shizznats]

Over the past few months, I've noticed that when I start my car (97 Legacy GT), it seems to 'choke' a bit and seems like its going to die for a few seconds until it picks up revs and then gradually revs to about 1500rpm and back down. Along with this, the smell of gasoline is present. However, with winter here in full force, the car just wouldnt start yesterday. I had to turn the key, quickly give it some gas, and then it finally started. After a few seconds of running it holds revs on its own. The smell of gasoline is still there for the first few minutes after starting the car. One more symptom: when the car is started and has been running for a couple minutes, if I tap the accelerator just to bring up the revs a tad, the car first hesitates (sort of chokes for a second) and then responds to my input. Once the engine has warmed up completely, it holds revs smoothly at 700rpm and everything seems to work ok. The other day while cruising down the highway I got a CEL; I stopped into autozone and scanned the code: it said: Catalytic efficiency below threshold. I cleared the code and it hasn't come back, but I'm worried that the car is not running on all cylinders when it first starts up, which could be pouring gasoline down the cylinder chamber and destroying my stromung cat... but wouldn't this give me a raging CEL every time I start the car??

In any event, what could be causing the hesitant starts? The plugs and wires were changed not too long ago. The car has a short ram intake and full exhaust. I get the sense that it runs quite rich, as my exhaust tip is pure black on the inside. Any help would be great... thanks.

[Huffer]

Subaru's run rich to begin with. In cold weather you're going to smell unburnt fuel because the computer is in startup mode. It's going to pump in more fuel because running lean at startup is like bowling in socks.

If your O2 sensor is on the way out, then that will cause a rich startup pretty much all the time, and will cause your MPG to drop because the ECU is getting a false reading and dumping fuel into the engine just in case.

I would buy a replacement O2 sensor just in case, but in the mean time you can do the following:
check your battery - is it reaching a full charge on your drives, is it holding a charge overnight
check your battery terminals - are they corroded or messed up? Clean terminals help tremendously
check your Idle Air Control Valve - if this is dirty or has a broken gasket you will get a fluctuating idle issue.

[shizznats]

New symptom: It hasn't been too cold lately so the car starts, chokes for a bit but doesn't turn off... but yesterday I started it and got a CEL a few seconds after starting the motor. I scanned the code and got a cylinder misfire on cylinders 1 and 3. Does this give any hints to what the cause of the cold starting rough idle issue is?

Battery looks fine... the O2 sensor might explain the car running rich, and I still have yet to check the IACV.

[Huffer]

Check the plugs to make sure they're seated correctly. Worst case scenario you could need a new coil.

[shizznats]

yeah I was thinking the coil could be the problem... I'll check the plugs first though. But would it make sense for the coil to cause cylinder 1 & 3 misfire at the same time?

[decke48]

1 and 3 share the same coil

[shizznats]

nice... so we might have found the culprit. I wasn't sure whether it was 1 and 2 or 1 and 3 that share the same coil. Looks like it might be time for a new coil pack. Thanks guys.

[Huffer]

ok, so a bad O2 sensor will cause a false reading, which will make the car run rich in this instance, creating an overfuel issue which fouls the plugs...

and you may have a bad coil pack too.

I'd still get that O2 checked/changed out.

[decke48]

it could be possible that the ecu wont self-learn the cold start. since pre-99 arent learning ecu's a reset might help.

[shizznats]

Interesting points... I might take out one of the plugs just to see what it looks like.

Also, how would I go about resetting the ECU? Is it just a matter of disconnecting the battery overnight?

[decke48]

disconnecting the positive terminal and steping on the brake for 30 seconds. (hasnt worked for me a couple times) to do it correctly you need to pull back the passengers carpet under the dash, removing the kick shield over the ecu, and unpluging the ecu for 30 sec and put it back together

[97legacygt]

Umm, your always supposed to disconnect the negative cable first so you don't end up frying yourself if your wrench makes contact with any other metal.

[decke48]

that pansy talk. :razz: yes your supose to do that so the terminal dont spark. and if theres hydrogen gas coming from the battery it doesnt explode. or they say

[97legacygt]

I'd rather be safe than sorry. I like my skin and eyesight the way it is now. Not with acid burning it up. :smt013