Toyota Nation Forum banner

1 - 20 of 22 Posts

·
Registered
Joined
·
26 Posts
Discussion Starter #1
So I have been fighting this Corolla low idle at the stop sign thing for several months now. I just happened, by chance, to turn on the headlights as it was looking like a bad storm was coming and I noticed that the low idle thing was gone all day. So if I turn the headlights off and the daytime running lights are on the low idle problem is back. Turn on the headlights and it is gone. Weird. Car will idle at 800 RPM steady as the first day I bought it. Turn off the headlights and the darn thing almost stalls at a stop sign. Everything turned off in the car except the headlights and all is fine. Everything turned on inside the car and the headlights on everything is fine. Turn off headlights and low idle problem is back again. I have decided to just manually turn on headlights and drive it.
 

·
2004 Camry LE
Cars
Joined
·
713 Posts
As far as I know the idle is controled by the car's computer.


However I would, for starters, scan for the codes.


What about regular maintenance things: throttle body cleaning, spark plugs (mileage dependent), etc. How about your ATF?


Good luck,
Sam
 

·
Registered
Joined
·
26 Posts
Discussion Starter #4 (Edited)
All the above mentioned items have been done, except auto transmission fluid. Will try that as it is due. Alternator was checked at Auto Zone and they said it was ok. I will go to another place and have it checked under a full load I am wondering does the throttle body need to be removed for a good cleaning?
 

·
Corolla Fan
2013 Corolla L
Joined
·
428 Posts
All the above mentioned items have been done, except auto transmission fluid. Will try that as it is due. Alternator was checked at Auto Zone and they said it was ok. I will go to another place and have it checked under a full load I am wondering does the throttle body need to be removed for a good cleaning?
Dang, you did it all? even spark plugs? wow. Dang that sucks. have you had to replace your serpentine belt yet? maybe its due for replacement or is too tight or too loose? check it's tension maybe?? I know I'm kind randomly thinking up ideas at this point. Did you already do the whole, disconnect your battery wait a few minutes, then reconnect, and let the ECU relearn all it's proper air/fuel and idle settings? all i can say is it sucks. I had it for a LITTLE over a month but once i got my next paycheck i did my seafoam throttle body cleaning and seafoam fuel injector/fuel system cleaning and i was golden. Heck not just my idle with the car parked was better, my purring while on the highway and roads at all speeds felt noticeably smoother, it "purred" much more smoothly that's for sure.

I hear about this problem and read about it for 10 gen corollas all the time, i really feel for you guys. I think the issue isn't as common in 10.5 gens (2011-2013). So I better consider myself lucky that i dont have to turn on my headlights to fix the idle in my car. Honestly it sounds electrical, could be a bad relay? Maybe your ECU relay(s) are going bad? i always check relays when dealing with electrical issues. Also it could be a bad or dirty MAF sensor, I've read about MAF trouble codes on corollas as well. You mean need to clean it with some CRC MAF cleaner.
 

·
Registered
Joined
·
46 Posts
Dang, you did it all? even spark plugs? wow. Dang that sucks. have you had to replace your serpentine belt yet? maybe its due for replacement or is too tight or too loose? check it's tension maybe?? I know I'm kind randomly thinking up ideas at this point. Did you already do the whole, disconnect your battery wait a few minutes, then reconnect, and let the ECU relearn all it's proper air/fuel and idle settings? all i can say is it sucks. I had it for a LITTLE over a month but once i got my next paycheck i did my seafoam throttle body cleaning and seafoam fuel injector/fuel system cleaning and i was golden. Heck not just my idle with the car parked was better, my purring while on the highway and roads at all speeds felt noticeably smoother, it "purred" much more smoothly that's for sure.

I hear about this problem and read about it for 10 gen corollas all the time, i really feel for you guys. I think the issue isn't as common in 10.5 gens (2011-2013). So I better consider myself lucky that i dont have to turn on my headlights to fix the idle in my car. Honestly it sounds electrical, could be a bad relay? Maybe your ECU relay(s) are going bad? i always check relays when dealing with electrical issues. Also it could be a bad or dirty MAF sensor, I've read about MAF trouble codes on corollas as well. You mean need to clean it with some CRC MAF cleaner.
I've done extensive research on this as I have the issue myself, and everything you've mentioned has been tried, as well as people changing their intake manifold gaskets (as was mine), batteries, going through relearn procedures with the computer, having techs analyse for any problems while the car is running, and even having their computers reflashed to no avail. Only message of hope I've seen is someone here mentioned he got lucky with some Lucas fuel injector cleaner, which prompted me to get a bottle and try it. I'm now on my second bottle (you do one per tankful) and not extremely hopeful as there's no change. I'm thinking it's the computer as well. It's one of the smoothest running cars I've ever owned with the lights on. If there was such a problem as to cause such an idle issue I would think there would at least be a glitch or something a couple hundred rpm's higher. But nothing. Smooth as glass and no bog when coming to a stop.

I'm getting a cover for the sensor on my dashboard to fool the computer into thinking it's night 24/7 so the lights stay on at all times when the car is on and automatically shut off when the car is off. DRLs on steroids. On the bright side it will be that much safer.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #8
Three different shops have scanned for codes and there are none!! I think I will just put some black electrical tape over the sensor on the dash and go for it.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #9
You know I never did disconnect the battery, but if that was the problem, why would turning on the headlights fix the low idle problem?
 

·
Registered
Joined
·
26 Posts
Discussion Starter #10
Never replaced Serpentine belt and that is another thing that really needs doing as the car has over 150k miles on it. Again I state, that if that was the problem, why does turning on headlights solve the low idle problem?
 

·
Corolla Fan
2013 Corolla L
Joined
·
428 Posts
You know I never did disconnect the battery, but if that was the problem, why would turning on the headlights fix the low idle problem?
Never replaced Serpentine belt and that is another thing that really needs doing as the car has over 150k miles on it. Again I state, that if that was the problem, why does turning on headlights solve the low idle problem?
It seems like an electrical power draw issue.. here's how i think about it: why would turning on your ELECTRICAL lights, fix an idle issue...? Well, the serpentine belt, battery, and alternator are all interconnected when it comes to electrical power draw, if any of those 3 is in bad shape and in need of replacement or repair, it can and usually does effect the other 2. And it can effect and create electrical power draw issues all over the car.

your serpentine belt is also connected to your water pump, A/C, crankshaft pulley.. So it MAY be effecting your engine idle too? make sure all 3 of those components are in tip-top shape first. (batt, alternator, and serpentine belt) and then reset your battery AFTER youve done your throttle body cleaning and fuel injector cleaning, otherwise its pointless to clean them if you dont reset the battery. lol
 

·
Registered
Joined
·
26 Posts
Discussion Starter #13
Ok, so the battery is new and less than 3 months old and checks good. I went to AutoZone and had alternator checked and the voltage regulator failed!! O"Reilly said the voltage regulator failed also!! So now I know I
need an alternator. I am going to replace the serpentine belt also. Should I replace the tension pulley as well? Now I am looking at prices on the alternator and local shops want $175 for a rebuilt one with lifetime warranty. I can go to Rockauto.com and get a Denso rebuilt for $130. All those parts come with a lifetime replacement warranty. I want the Denso just because I know it is exact replacement. Thoughts from anyone?
 

·
Registered
Joined
·
46 Posts
try resetting the car by removing the battery cable. You might be surprised or not.
I did this after cleaning my throttle body trying to alleviate the problem. I will say that before I thoroughly cleaned the gunk around the butterfly with a toothbrush and TB cleaner the car was bogging down to 400 rpm and almost stalling almost every time I came to a stop, to jump back up and then settle back down to 600 rpm, a rough idle. After cleaning and resetting the computer the bog never went down past 600 and idle settled to around 625. It was definitely an improvement. If it would go up another 25 the idle would be smooth, but it won't stay there for anything longer than a few seconds before it slowly settles on down to 625. It did make a difference but there's still that dip at stops that shouldn't exist and the idle is still too low.

First time I did a reset was as I mentioned after I cleaned the TB. I reconnected the battery and let the car idle in park for about 10 mins then drove it around as instructed. 2nd time I tried it was after I was still searching around the net and found people saying you needed to do it the "Toyota way" which was fully warm the engine, then shut it off. Turn the key to the on position once, then back to off. Now crank the car. With e-brake on and foot on brake put car in drive and let car idle for 5-10 mins until idle resets. No change for me. 3rd time I tried it someone else had said only turning key once was wrong, you have to turn key to on position and back off twice, THEN crank car and let idle same way until idle smooths out. No change again.

At this point I was done torturing the car and myself.

I will say cleaning the throttle body did make a difference but it didn't solve the problem that's causing bog and low idle. I also wanted to add if you do clean it while still on the engine and with a toothbrush make sure it's not old. I made the mistake of using an old toothbrush and pieces broke off inside. I was very fortunate they didn't fall down into the intake and I was able to fish them out.

As far as the question of why would headlights make a difference in idling, the computer automatically switches to "headlights on" mode as it also does with the AC compressor on, to keep up charging and prevent bog, which works perfectly. I would think if the otherwise low idle were anything besides the computer, the computer would be working to overcompensate for something and/or eventually throw a code since this is a screwed up way for the motor to be running. But nothing. Car is comfortable doing this after over 1,000 miles and several months of my driving it. That's how I'm beginning to really lean towards this being a computer issue. I've thought about the possibility of changing the ECM for a later year (10.5 gen) but don't know enough to know if this is even doable or after spending all the money which I can't really afford and possibly screwing something up even worse if it would solve the issue so I'm not going there, myself.

If I can just solve the whole issue by turning on the lights then so be it. AFAIK from research, this generation and model has no "bulb out" warning system so I'll just check my halogen bulbs every few weeks to make sure nothing is blown. That's really my only concern at this point. Cops in town here LOVE stopping you for blown out bulbs. :stop:
 

·
Registered
Joined
·
26 Posts
Discussion Starter #15
Well I am going to replace my bad alternator first and see if that makes any difference on the low idle issue. If not then I will drive with the headlights on and replace the bulbs with brighter ones when needed. I am going to replace the serpentine belt at the same time. I have talked to Toyota parts and I of course will not buy the rebuilt one from them at $300 with a 1 year warranty. I am fortunate that the alternator is on top, so easy to get to.
 

·
Registered
Joined
·
46 Posts
Well I am going to replace my bad alternator first and see if that makes any difference on the low idle issue. If not then I will drive with the headlights on and replace the bulbs with brighter ones when needed. I am going to replace the serpentine belt at the same time. I have talked to Toyota parts and I of course will not buy the rebuilt one from them at $300 with a 1 year warranty. I am fortunate that the alternator is on top, so easy to get to.
I've had nothing but good experience with Rockauto and would only use OEM which I'm assuming is Denso in this case. When Chevrolet had that deal with Toyota and was basically turning out Corollas and rebadging them as a "Prizm", the only problems they were having over the Toyotas were AC Delco parts Chevrolet had the bright idea to use instead of Toyota's Denso parts, to save a dollar. I agree changing your belt is a good thing to do at this point. Mine needs changing as well.

Whatever you do, I highly suggest you do not order from Amazon, even if the seller says "Denso" or "Toyota" or whatever. I and many others have been burned by knock off sellers sending me cheap Chinese parts (for another vehicle) that failed soon afterwards and had a mechanic confirm that's what the problem was and he said don't ever order car parts from Amazon.

Please keep us updated on what happens. :smile:
 

·
Registered
Joined
·
26 Posts
Discussion Starter #17
Ok so I priced a rebuilt Denso from O'Reilly and it is $255 and I just ordered one from RockAuto.com and delivered with 3 day delivery charge it is $151. Son in law will install and check it all out for me as he is off next week and an ex mechanic. I am wondering about that tension pulley at the bottom (maybe it is a idler pulley) not sure, I am getting a new Gates serpentine belt as well. Will post results.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #18 (Edited)
Okay, the alternator arrived today and got a new belt. Will have brother in law install. You know the funny thing about this is the car has never had a check engine light on and there are no codes at all, ever!! So we will see but I know I needed the alternator for sure.

Oh by the way it is hot as you know what in Texas also!! We are in the greater Houston area.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #20
Did the new alternator fix your low idle issue....?
No it did not. But after doing all the things I did do it is some what better. Mass Air Flow was black and covered in carbon. Bought a can of MAF cleaner and removed the MAF, sprayed it let it dry and sprayed it again. re-installed and then drove the car for about 100 miles, so the computer could learn. Forgot to tell you I had disconnected both battery terminals prior to doing this. I should have cleaned the area where it mounts on the engine as well, but did not. It was horrible and stalled a couple of times right after start up but got better and better as time went on. It was fine for about 6 months and now is back to its old tricks.
. Head lights on, no longer works. Must put in neutral at stop sign or red light.I am done throwing money at it and will just drive it until it quits. I wish it would throw some codes then maybe it could be fixed. Good luck if you are having the same problem. Read this whole thread it is pretty informative. Before tearing engine down try all other things first as an engine rebuil is expensive.
 
1 - 20 of 22 Posts
Top