cold start help

[ugaucin]

My 94 L legacy has a very rough time when i comes to cold starts. Its on every cold start. I turn it on, it starts and then it goes into a very very rough idle and it dies. I have to give it gas to start up, after that it will run fine. Its everytime I try to turn it on after being off for a while. Any ideas it can be?

[macipusy]

Mine does the same thing. I am suspecting the IAC as the culprit...it's almost as it's a little too closed when cold, before warm coolant runs through the IAC body.

[kimokalihi]

Either that or the coolant temp sensor.

[lucas]

id start with the coolant temp sensor its cheaper.

[scoobydoo94turbo]

Not sure what they call it out your way but its been -15 to -30 here for a few days and my idle has also been jumpy, I pulled the IACV hose off and sprayed some combustion chamber cleaner into it (one the motor was warm and engine not running) let it sit for 20 minutes, cranks over for 3 seconds then finally starts due to the iac being flooded with fluid but it works great now, ive done this in the past also, quick fix or quick clean call it what you wish! Sea foam is the same crap but combustion chamber cleaner is an aerosol can and sea foam is a pure liquid..

[lucas]

gotta be careful doing that as it can eat away the seals on the inside of the valve. Your correct is a super effective quick fix but could cause more problems in the long run. Best bet is to take that damn thing off go to subarus headquarters In tennessee or where ever and throw it through the window for designing such a retarded sensor. No seriously though go to the deal and but the subaru upper intake cleaner, or GM upper intake cleaner and clean it that way.

[ugaucin]

Would a bad valve cause it to bog?

[lucas]

its possible. Think about it these cars arnt getting younger so every year more and more crap builds up in that tiny little sensor, so every time we clean them we could possibly be destroying them. The guys down the street at my local subaru shop recommend I use GM upper intake cleaners. take it off soak some in there use q-tips to get the crud out of it.

[wtdash]

Try the CTS first...they are a 'maintenance item' as they tend to need replaced on many older Subies.

[lucas]

^start cheap

[ugaucin]

But my legacy doesn't have a code.

[kimokalihi]

It won't have a code for the coolant temp sensor.

[ugaucin]

Really? My wagon did.

[kimokalihi]

Well I guess it might but not guaranteed.

[ugaucin]

I'll still change it out. It won't hurt.

[Legacy777]

The coolant temp sensor has a HUGE affect on all the fuel enrichment including cold starts. If someone is having a starting issue like you described, the coolant temp sensor is usually the first thing I recommend. Sometimes it can leave a code, but most of the time it won't because it's still within the appropriate range for being "warm" but isn't working properly at cold temps. The ECU's on these cars are not smart enough to know that.