I bought my 03 Corolla S about a month ago and had an allignment done, tires rotated, and the rear drums tightened up. I then replaced the air filter, ac cabin filter, fuel injector cleaner, and bought a serpentine belt (have yet to replace). Anyways, the car ran good but recently it has begun to idle very low at stops (400-500rpms). I would be alright with this but when I originally bought the vehicle it would idle around 700-800 at stops and didn't feel as rough either. The car is not stalling but doesn't feel smooth at idle when it gets down that low. It does it with the ac on and off. Also it appears when the vehicle is in gear or neutral. Any ideas? Clean throttle body, maf, run fuel cleaner again, replace 02's? One more thing, there is no check engine light.
Clean the TB (not sure if you did) and the idle air control valve.
Do you have a picture or diagram of where the iac valve is located? Also, should the throttle body be removed prior to cleaning or would cleaning it still in place suffice?
Do you have a picture or diagram of where the iac valve is located? Also, should the throttle body be removed prior to cleaning or would cleaning it still in place suffice?
If you do not want to remove it, just spray the hole to IACV and clean the TB while you are at it, making sure to clean the butterfly valve well. Use throttle body cleaner and not just carb cleaner with a soft brush. I am not sure if you can clean the TB with the car running, on my 05 you cannot due to the massive vac leak, but I have DBW, not sure if that matter. It is better to clean it while the engine is running if you can. Massive amounts of smoke will pour out of the exhaust while cleaning or at starting up, that is normal. It is advisable to do this a couple of days before an oil change.
Update. Performed Seafoam procedure and throttle body cleaning this morning. Once completed I waited about a half hour and started the car. It took a little while for it to fire up and it bogged quite a bit but finally got it going and the smoke started pouring out. I threw it in drive and took it for a spin. Within a minute the check engine light came on and the low idle was still there. I drove the car over to advanced auto parts and they scanned the car. Pulled up multiple misfire code and they cleared it for me (hasn't come back . Sounds like a common thing with the newer cars after running seafoam through them and they start to bog/misfire. Anyways, I haven't noticed an improvement in the idle (still at around 400rpms or slightly lower than the half way hash between 0 and 1000 rpms). Normal is around 800-900rpms correct? I have maf cleaner that I was contemplating doing next...any other thoughts. Maybe completely dissasemble the throttle body/iacv like was suggested ^? I was hoping the seafoam & quick throttle body cleaning would work but so far it hasn't appeared to fix the problem.
Normal idle is 750 +- 50 RPM. Did you try to reset the ECU?
Yea, I disconnected the negative terminal and also cleaned out the maf while I was at it. It started raining so I couldn't get to the pcv valve. Idle @ stops have dipped into the 350rpm region @ times and begins to have a moderate shudder. I may end up having to throw in the towel here and take it in because the problem has progressed pretty quickly over the last couple of weeks.
That sucks. Check the spark plug gap and clean the MAF, as that is the next likely cause. Any CELs? Hear any vac leaks?
No improvement after cleaning the maf sensor out and I'm not throwing any codes. I may try removing the pcv valve along with the throttle body, and iac tomorrow to clean. I just sprayed the throttle body and iac holes while the engine was off. I made sure to open up the butterfly valves and spray within the throttle body as well. It didn't look that dirty on the outside. When changing my oil today I did notice what appeared to be a small coating of oil building up on the bottom portion of the engine. Couldn't locate the origin though. What's the best method for listening for vacuum leaks? I've used the hose method for listening to rockers, etc.
No improvement after cleaning the maf sensor out and I'm not throwing any codes. I may try removing the pcv valve along with the throttle body, and iac tomorrow to clean. I just sprayed the throttle body and iac holes while the engine was off. I made sure to open up the butterfly valves and spray within the throttle body as well. It didn't look that dirty on the outside. When changing my oil today I did notice what appeared to be a small coating of oil building up on the bottom portion of the engine. Couldn't locate the origin though. What's the best method for listening for vacuum leaks? I've used the hose method for listening to rockers, etc.
For anything major, you may hear the leaks. If it is the intake manifold gasket, spray carb cleaner around the intake manifold and listen for the revs to increase. The intake manifold is this: http://www.dragtimes.com/images-clas...0112035800.jpg
Just carefully spray around it when it is on the car, while the engine is running and listen for a rev increase. Also, before you do that, inspect all vac hoses for cracks and look for hoses that may have come off. After you do that, might want to check the gap on the plugs, are they original? Clogged PCV valve could cause a low idle too. See if it passes the shake test, then clean it with carb cleaner, let dry, and reinstall.
For anything major, you may hear the leaks. If it is the intake manifold gasket, spray carb cleaner around the intake manifold and listen for the revs to increase. The intake manifold is this: http://www.dragtimes.com/images-clas...0112035800.jpg
Just carefully spray around it when it is on the car, while the engine is running and listen for a rev increase. Also, before you do that, inspect all vac hoses for cracks and look for hoses that may have come off. After you do that, might want to check the gap on the plugs, are they original? Clogged PCV valve could cause a low idle too. See if it passes the shake test, then clean it with carb cleaner, let dry, and reinstall.
I just watched a video about vacuum leaks that said propane works very well at detecting the source as well. I'll probably just end up using throttle body cleaner like you suggested first though. Yes, the plugs are most likely the originals but the car only has 98k miles.
I just watched a video about vacuum leaks that said propane works very well at detecting the source as well. I'll probably just end up using throttle body cleaner like you suggested first though. Yes, the plugs are most likely the originals but the car only has 98k miles.
Time to get those suckers out of there, plugs are good for 100K miles but are often replaced earlier. Stick with NGK or Denso iridium plugs only, they come pregapped, so dont touch them. That may not solve your problem, but may help with mileage and power. If you check the gap on the old ones, and they are not in spec, that can cause a low idle too.
In the process of cleaning out the pcv valve and noticed I don't have the metal clip that slides onto the rubber hose that is pictured here: http://i171.photobucket.com/albums/u...i/PICT1199.jpg
I'm not sure if that would open up the system up enough to allow a vacuum leak. It just allowed me to pull off the hose rather easily. Maybe I'll try pinching the hose shut while it's running with my hand to see if it makes a difference.
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. I drove the car over to advanced auto parts and they scanned the car. Pulled up multiple misfire code and they cleared it for me (hasn't come back 
. Sounds like a common thing with the newer cars after running seafoam through them and they start to bog/misfire. Anyways, I haven't noticed an improvement in the idle (still at around 400rpms or slightly lower than the half way hash between 0 and 1000 rpms). Normal is around 800-900rpms correct? I have maf cleaner that I was contemplating doing next...any other thoughts. Maybe completely dissasemble the throttle body/iacv like was suggested ^? I was hoping the seafoam & quick throttle body cleaning would work but so far it hasn't appeared to fix the problem.
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