It revs up and idles good for almost 5 minutes then the rough/low idle begins. Always idles good when cold. Changed the IACV today and made no difference. Also cleaned throttle body and mass air flow sensor. Had a a good mechanic to run codes and look at it but not found anything yet. Any help would be greatly appreciated.
2004 Corolla Rough Idle When Warm
- Thread starter corolla15
- Start date
Sounds like a vacuum leak on the Exhaust Gas Recirculation (EGR) circuit. That only opens up when the engine is warm. IAC wasn't the issue. IAC increases idle when the engine is cold, when the A/C Compressor clutch is active, or when steering the car while parked, but it does not effect the idle trim when the engine is warm up and none of the other conditions are occurring.
Check the EGR system, don't just replace it without verifying an issue there.
Check the EGR system, don't just replace it without verifying an issue there.
Thank you so much for the help. I just changed the EGR and it did not help the low/rough idle. The car has 138k miles and runs great. My mechanic seemed to think there might be a timing chain noise and the guides could be worn some. He said his scanner showed misfire on 2,3, and 4 cyl. He also resealed the intake and throttle body gaskets. Please let me know what you think.
Grab a bottle of water and start spraying around vacuum lines when the engine is warmed up and running rough. Check around the EGR circuit and those hoses. If the idle improves when you spray an area then goes back to running rough, you found your leak.
I would say to check your spark plugs with the misfires, but given that it only does this when running warm, I am still thinking there is a vacuum leak around there somewhere.
I would say to check your spark plugs with the misfires, but given that it only does this when running warm, I am still thinking there is a vacuum leak around there somewhere.
I have a 2009 Corolla that idles very low and rough when I brake. I took it in to Modesto Toyota here in Cali and they did a compression check and said number 4 cylinder was bad,so I authorized a valve job...when they got apart said they couldn't do a valve job the valves were to pitted and the walls to thin. So I purchased a used engine and had them install it.....I get my car back it idles great for 1 day and now the idles is starting to do the same thing, ideling low and rough when I brake!!! I did have 200K on the old engine...However it was running great!!! so I'm a little pissed to say the least...they sold me an engine and I probably didn't need one yet!!! I took it back and they haven't a clue why the idle is doing that.
any advice? outside of not going back to Modesto Toyota
any advice? outside of not going back to Modesto Toyota