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2003 Corolla Irregular Revs When Cold

by partyone, January 23, 2007

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Hi to all and thanks for checking out my problem,

When my '03 corolla is "cold started" around 0 degrees celsius and below, the colder it becomes it is even more erratic. What happens is the revs reach 2200rpm and drops to 1800rpm and it does this constantly up and down until the temp gauge senses a touch of heat. Its fine when it is warm but you have no idea how silly it sounds when this happens. The dealer has replaced the mass air sensor but its still an issue, anyone heard this before?

F

Bikeman982

Hi to all and thanks for checking out my problem, When my '03 corolla is "cold started" around 0 degrees celsius and below, the colder it becomes it is even more erratic. What happens is the revs reach 2200rpm and drops to 1800rpm and it does this constantly up and down until the temp gauge senses a touch of heat. Its fine when it is warm but you have no idea how silly it sounds when this happens. The dealer has replaced the mass air sensor but its still an issue, anyone heard this before?

 

F

There are a lot of people that have a similar problem, if this is like the idle hunting problem.

 

Check previous posts for their troubles and attempted solutions.

Here is the lengthy and well documented thread that poster montreal started a while ago with this erratic behavior. Unfortunantly, the fix is not readily available right now - though one is in the works.

https://www.corolland.com/forums/index.php?...l=hunting+idle#

Bikeman982

Lots of people with a similar problem.

Hi everyone I believe to have found the issue with my Corolla S. It was well under zero degrees today and thought of an idea. After work (I'm employed at a BMW retailer) I "cold started" my car, we sprayed brake cleaner under the plastic trim that covers the valve cover and guess what. It did the same revs fluctuations as always but when we sprayed the brake it ran very rough, which in turn means its taking in air (equals a leak) where it is not supposed too. I will perform the same test tomorrow with the cover removed to pin point exactly where the problem is, I will keep you posted.

F

Hope that works for you.

My 03 CE 5-speed has had this since new and has no mechanical issues. Only happens on cold days for the first few minutes.

Causes lousy gas mileage in short trip winter city driving.

Let us know what you find.

Hope that works for you.

My 03 CE 5-speed has had this since new and has no mechanical issues. Only happens on cold days for the first few minutes.

Causes lousy gas mileage in short trip winter city driving.

Let us know what you find.

Well i'm happy to inform everyone with these 5-spd cars that i found the "idle" problem, my car has an intake manifold gasket to cylinder head leak. I am bringing the car to the dealership monday to have it repaired. Now because it is a composite "plastic" intake manifold, it may be possible that it does warp in these weather conditions. Time will tell after gasket is replaced.

Keep us in the loop.

Mine does it since new and only in cold weather. Perhaps something contracts in the cold and seals when parts expand.

If it fixes the problem, I'll get to my dealer on extended warranty.

Thanks for the update.

I doubt its a manifold leak if its a newish car. Toyota in my experience usually build things mechanically to a very high standard.

I believe the hunting of idle in cold temps is to do with the tune of the car.

Im unsure whether Toyota flash the same program into both manual and automatic cars, obviously despite what some people may believe, every car that comes down the assembly line is different in tolerances inside the motor and one generic tune flashed into every single vehicle does not make a car operate under optimum conditions.

Unfortunately Toyota have a history of making it near on impossible to be able to simply plug a laptop with an aftermarket tuning program into the OBD2 port which allows alterations to be made to the factory ECU.

If anyone here has played with an aftermarket program, you can tune out hunting at cold start, and the amount of parameters you can change and alter is mind boggling. So it boils down to what kind of conditions your car sees most often and tune it to suit, or if you are an avid enthusiast, you log and tune your car everyday of the week, year in, year out so you have a tune for every season from winter to summer.

If its a stock car in extreme cold, my advice would be to use an oil with good flowing characterisitcs at low temp to help turn the motor over easy and dont wait for the car to warm up, just get in and start driving to get it up to operating temp ASAP, dont rev the motor past 3 grand till the temperature gauge gets to normal.

Because of the cold, not only will the O2s take longer to warm up, there are other adjustments to consider such as IAC steps, coolant temp, fuel trims, commanded idle speed, AFRs, and alot more sensor info I wont delve into because it really is complex unless one has experience in tuning.

Agree with you.

My son's 2003 LE auto doesn't hunt. My 03 5-speed does it but only under certain conditions.

These computer controls are like a PC. When you tune one parameter, you may very well affect another one. That's what makes it so difficult.

Toyota's TSB reflash almost totally cured the sulphur "farts". Perhaps they will cure the cold idle or perhaps not.

According to a Toyota tech and an independent master tech, the condition is annoying but won't shorten engine life.

Can't have everything.

Bikeman982

Not that it is a solution to an idle hunting problem but it is not recommended you keep your car idling for long periods of time.

Basically either drive it, or shut it off. If you are stuck in traffic, that is another story.

Sorry for those who have doubted the intake leak, hate to break it to ya but it was and the dealer has since replaced the gaskets. So if your 5-spd has this issue buy a can of brake clean and while the car is running spray the intake manifold where it bolts to the head. If the engine chokes guess what you have a leak, it's the oldest trick in the book. Problem solved here on my side :-)

F

Very interesting. I've wondered about that - since they moved from the metal, longer length runners and moved to the more compact composite intake - that there might be some issues with that. But they also did some many other changed for the transition between the 8th and 9th gen Corollas - people with idle hunting issues had a tough time diagnosing it. I guess it pays to do stuff "old-school" before you break out the fancy (expensive) tools.

Bikeman982

Sounds like a great method to check for intake leaks.

I cleaned my daughter's intake using brake cleaner and as soon as I sprayed it, the car would shut off.

I started using just a little with a higher idle and it worked better that way.

Now she has a cleaner engine intake and I reset her CEL that was on.

I will have to ask her if the CEL ever came back on.

Will surely explore it with dealer.

However, I don't feel my issue may be an intake leak. It doesn't correlate entirely with temperature so may not be contraction.

Some cold days, it doesn't "hunt", but some it does. I think it's a combination of computer signals just like the one that caused the infamous sulphur "farts". Only under certain conditions would your Corolla pop an SBD.

Thanks for the update. Glad your idle issue is apparently solved.

Bikeman982

Sounds like a great method to check for intake leaks.I cleaned my daughter's intake using brake cleaner and as soon as I sprayed it, the car would shut off.

 

I started using just a little with a higher idle and it worked better that way.

Now she has a cleaner engine intake and I reset her CEL that was on.

I will have to ask her if the CEL ever came back on.

The CEL came back on after about a day of driving.

 

She has a clean intake, so I assume a sensor is bad.

I will have to do some further troubleshooting.

Ti-Jean

Sorry for those who have doubted the intake leak, hate to break it to ya but it was and the dealer has since replaced the gaskets. So if your 5-spd has this issue buy a can of brake clean and while the car is running spray the intake manifold where it bolts to the head. If the engine chokes guess what you have a leak, it's the oldest trick in the book. Problem solved here on my side :-)F

I wonder what Montreal has to say about this simple fix?

How come Toyota engineers and technical support have apparently gone to great lenghts to find a solution for this issue and oversaw this simple solution?

Bikeman982

Sorry for those who have doubted the intake leak, hate to break it to ya but it was and the dealer has since replaced the gaskets. So if your 5-spd has this issue buy a can of brake clean and while the car is running spray the intake manifold where it bolts to the head. If the engine chokes guess what you have a leak, it's the oldest trick in the book. Problem solved here on my side :-)F

I wonder what Montreal has to say about this simple fix?

How come Toyota engineers and technical support have apparently gone to great lenghts to find a solution for this issue and oversaw this simple solution?

They neglected to check for the obvious.

 

 

Possible, but maybe only for a few Corollas.

As I mentioned before, my 03 CE 5-speed has done this since new.

Never a CEL.

Weird thing is that the problem only happens in cold weather but isn't linked totally to temperature. This morning, for example, the temp was around 30 degrees F which is cold for North Carolina. No hunting idle at all.

Yesterday, it was warmer, but the idle hunted until warmup in about two minutes of driving. I still think most cases of this are caused by the computer reacting to various combinations of sensor input.

The reflash TSB almost 100% cured the sulphur farts for both of our Corollas, auto & 5-speed.

Good the problem above had a simple solution. Don't think it's universal though.

Bikeman982

Possible, but maybe only for a few Corollas.

As I mentioned before, my 03 CE 5-speed has done this since new.

Never a CEL.

Weird thing is that the problem only happens in cold weather but isn't linked totally to temperature. This morning, for example, the temp was around 30 degrees F which is cold for North Carolina. No hunting idle at all.

Yesterday, it was warmer, but the idle hunted until warmup in about two minutes of driving. I still think most cases of this are caused by the computer reacting to various combinations of sensor input.

The reflash TSB almost 100% cured the sulphur farts for both of our Corollas, auto & 5-speed.

Good the problem above had a simple solution. Don't think it's universal though.

The solution may work for some people and it is certainly worth a try.

 

 

I think I had the same thing with my 94 DX. If it was really cold out, and was started for the first time, it seemed as though the RPMs kept going low at idle, and almost died. A minute or so later, once the engine warmed up, it was okay. Not sure what it really is, but I just changed the plugs, pcv valve, and oil, and im hoping itll help.

Ive had no CELs either.

My '06 Corolla is going into Toyota for this problem on Sunday night. It is suppose to be brutally cold out, so i'm hoping that they'll be able to duplicate the problem. It only happens every 20 starts or so, but it definitely happens. I have a feeling it's the way that Toyota programmed the computer at the factor, because it seems to get confused with engine temp. When the car is hunting for an idle, the car thinks that the engine/air is already warm, but then doesn't get enough air flow and starts to lay off the gas... of course then it idles rough and damn near stalls.

It suprises me that in this day in age we are still having this problem. It is something that has been ongoing since the advent of electronic injection, and you would think car manufacturers would have figured it out by now...

Bikeman982

My '06 Corolla is going into Toyota for this problem on Sunday night. It is suppose to be brutally cold out, so i'm hoping that they'll be able to duplicate the problem. It only happens every 20 starts or so, but it definitely happens. I have a feeling it's the way that Toyota programmed the computer at the factor, because it seems to get confused with engine temp. When the car is hunting for an idle, the car thinks that the engine/air is already warm, but then doesn't get enough air flow and starts to lay off the gas... of course then it idles rough and damn near stalls.

It suprises me that in this day in age we are still having this problem. It is something that has been ongoing since the advent of electronic injection, and you would think car manufacturers would have figured it out by now...

I think cars are designed with normal operating temperatures in mind.

 

There is some consideration given to the warm-up process, but mainly it is overlooked.

Extreme temperatures really throw off the cars computer and normal settings.

  • 1,424 posts
My '06 Corolla is going into Toyota for this problem on Sunday night.

Is your car a stick or auto?

As you know I drive a 2005 LE, which is an automatic, and I've never had my car do anything but idle perfectly.

Sometimes it takes a while to start, but nothing excessive, and nothing different from other Toyotas. I'm just used to cars that start faster like V8 Fords.

My son's 2003 LE auto doesn't have the erratic idle issue and he lives in PA.

His LE had a worse case of the "farts" than my 03 CE 5 speed.

I say it's normally caused by the engine computer. Intake leaks are probably only responsible for a few problems.

Both my dealer and independent mechanic have seen this in a lot of Corollas and say it's not correctible but shouldn't shorten engine life.



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