Rough Idle When Cold

U

Ua22plumber

New Member
#1
#1
This is my wife's 2004 corolla which I rarely drive. I drove it today and after driving for three miles I came to a stop sign and while sitting at the stop I thought the engine was going to die, but it did not. That's when my wife says to me "oh ya it's been doing that for a while when it's cold.
I'm in New York at it was 25 degrees at the time...
The car has over 110,000 miles on it.
Any suggestion on what to check for the cause?
 
U

Ua22plumber

New Member
#6
#6
when I google that code the were so many post about people changing the O2 sensor and it was not actually the problem... I don't want to waste $90 on something that isn't broke...
I think a saw something about the intake gasket causing problem and needing to be replaced. any thought? thats only $5 bucks...
 
Scott O'Kashan

Scott O'Kashan

Super Moderator
#7
#7
Always diagnose first. Never just replace parts hoping it will fix a problem. As you correctly point out, the parts replacement routine can get very expensive.

To diagnose a vacuum leak, use a spray bottle of water and slowly spray the water along vacuum lines and gaskets as the engine is running. If you suddenly spray an area and then the engine idle changes, you've found a vacuum leak. What happens is that the water momentarily plugs the vacuum leak and improves the engine idle.
 
Donabed Kopoian

Donabed Kopoian

6 Speed Master
#8
#8
You should be changing O2 upstream sensors every 60,000 miles anyway to keep up fuel economy. If you replace it and it fixes the code you're set. If you replace it and it doesn't, then you have a fresh O2 sensor that you are probably due on as it is, and then you can start looking for other things.

Scott, don't think vacuum is the issue. Usually vacuum leaks will throw "Lack of HO2S Switch: Sensor Stuck Lean", but I could be wrong.
 
U

Ua22plumber

New Member
#9
#9
ok i got the 02 sensor. there is only one upstream sensor, correct? and one down stream sensor.
and its between the engine and the fire wall under a heat shield?

I just wanted to mack sure because auto zone.com had a diagram and it showed more than that but I think it was for a v6 or some thing.

Figured I'd change out the 02 sensor and see if that fixes the problem. if not hopefully it helps with the MPG's like Donabed Kopoian said.
 
Donabed Kopoian

Donabed Kopoian

6 Speed Master
#11
#11
Yes, only one upstream sensor. Don't worry about the downstream sensor until it throws a code, as that one just checks to make sure the catalytic converter is working. The upstream one does all of the stoich measurements, and thus impacts your mpg (I replaced mine at 60,000 in the Matrix and it had fouling on it, and the replacement improved my mileage by about 2).

Upstream is between catalytic converter and engine head. On my Matrix I managed to remove it by pulling the heat shield and using a wrench on it.
 
05corolla

05corolla

Super Moderator
#12
#12
This is definetly the intake gasket. People have the wrong diagnosis. Make sure to buy the orange one instead of black otherwise be doing it again in 2-5 years
 
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