New to me Corolla with rough idle is making me crazy trying to figure it out! It idles at a steady RPM, accelerates normally, and starts easily. So far I have cleaned the throttle body, air intake valve, mass air flow sensor, changed the plugs (they looked good), new PCV valve, new air filter (had an oiled K&N) and visually checked all the vacuum hoses. All of that only made it slightly better, Does anyone have any other ideas? Car is 2004 with 110k miles it's making nuts with the idle
2004 Corolla 110k miles with poor idle
- Thread starter fozzdesy2001
- Start date
The Corolla's from that era all seem to exhibit this issue to varying extents. Assuming you have no vacuum leaks, no exhaust leaks, fuel trims are normal (+/- 10) and the belt tensioner isn't ready to fly off (not uncommon on those), that is the best it'll get.
If it had an oiled K&N you may want to replace the MAF and not just clean it.
Are you sure it's actually a bad idle and not vibrations from a bad engine mount?
Intake leak?
That’s a rabbit hole you don’t wanna go down. If none of the mounts are severely torn or leaking, it becomes an expensive parts cannon exercise.
Hook up a scan tool capable of live data, especially fuel trims but of course check for trouble codes while you're at it.
Does it only idle rough with the A/C compressor on? What is the idle RPM?
New to you as-in, have you even put a fresh tank of gas in or might it have sat a while and have old fuel? Might also be worthwhile to put a double dose of fuel injector cleaner in it.
Does it only idle rough with the A/C compressor on? What is the idle RPM?
New to you as-in, have you even put a fresh tank of gas in or might it have sat a while and have old fuel? Might also be worthwhile to put a double dose of fuel injector cleaner in it.
Had a 2005 and can confirm the idle is all over the place with these things. Sometimes it would be fine, other times it would idle low and rough enough to rattle the fillings out of your teeth. Didn't care enough to try and fix it.
That would be my guess.
No codes pending or stored. I sprayed some carb cleaner all over the place no idle changes so no leaks i guess
short trim read -1.6 long was 2.6 might not have waited long enough for it warm up all the way.
it certainly could be the mounts I was hoping for something easier
I ditched the K&N dose the oil kill the MAF?
No, only if it's over oiled. It doesn't really kill the MAF it just gets gunk on it and would need to be delicately cleaned with a MAF sensor cleaner.
Bud_One
Site Donor 2022
The oil kills the MAF.. I had a 2003 Vibe with the 1ZZFE engine and had a MAF go out due to excessive oil from over oiling the filter .
