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ryan_h

Will Not Idle Properly After Disconnecting Battery

22 posts in this topic

Today, I replaced the drivers side headlight on my 2002 es300. to do so, I had to disconnect the battery to see what I was doing and fit my hand. When I reconnected the battery and went to start the car, it started as normal for about 1 second, then died. I then found out I could keep it alive by holding down the gas (try having to drive 20 miles attempting to keep the car alive this way). Any ideas? Called the dealership this afternoon and the guy in the service department told me to keep the car idling around 650 rpm for 10-15 minutes and the car would relearn correct fuel/air ratios. Did this to no avail. No Check Engine light, car runs fine and always has until disconnecting the battery. HELP!

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Update:

Cleaned the Mass Airflow Sensor today. Still nothing. The car will idle around 200 RPM if the engine is cold but as soon as it heats up, it will die. I understand auto theoreticals but I really don't know too much as I have never actually done it myself. Anyone have any ideas? I am willing to do just about anything!

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ryan h,

Your problem started when you disconnected the battery, and then reconnected it. I suspect that that is the source of your problem. All kinds of crazy electrical goings on can occur when improper voltages are supplied in modern cars. I would double check your battery connections to ensure that you don't have any corrosion and that they are making good contact. Then I would follow your Lexus Tech's advice one more time. If that doesn't do the trick, it may be prudent to just bite the bullet and let them track down your problem. By the way, an idle of 200 rpms is way to low. It should be in the range of 750 - 800 without the air conditioning on on most cars. Good Luck!

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ryan h,

Your problem started when you disconnected the battery, and then reconnected it. I suspect that that is the source of your problem. All kinds of crazy electrical goings on can occur when improper voltages are supplied in modern cars. I would double check your battery connections to ensure that you don't have any corrosion and that they are making good contact. Then I would follow your Lexus Tech's advice one more time. If that doesn't do the trick, it may be prudent to just bite the bullet and let them track down your problem. By the way, an idle of 200 rpms is way to low. It should be in the range of 750 - 800 without the air conditioning on on most cars. Good Luck!

Yeah, I knew 200 was low, I was thinking around 650 to 800 myself. I had been running 87 octane gasoline and put in 14 gallons of 93, which helped somewhat, and took it on a 100 mile interstate trip. It **HELPED** but not much at all. I think I am going to clean the idle air control valve tomorrow. If that doesn't work, I am taking it in. Unless anyone has any other ideas! Thanks though! I will keep you all posted as to what it is!

Ryan

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Hi, I also have a 2002 ES300 and change the battery today and am having the same issue. Did you find a resolution?

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This used to happen to me in my 02 when I would disconnect my battery to reset to factory defaults for the tranny (see 45+ page thread pinned at top of this forum). Scared the crap out of me the first time, but then knew it was to happen anytime I disconnected the battery.

The ECU is learning the MAF sensors, TB position sensor, etc, etc. It will clear out in a few hours (definately less than a day). I would drive around on all kinds of roads, just remembering to have to give it some gas at the stop lights so I wouldn't stall. Often I would through it in N, so I could give it a little gas. Don't worry, from experience, it clears out and will be idling normally in a short period of time.

steviej

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Same problem with my 02 es300. I did what the stevej said but that did not help me. Turns out that my throatle plate was very dirty. My friend, the learn it yourself mechanic, and I cleaned it with a can of carburator cleaner and now my idle is holding at 300-500 rpm. This job requires that two persons; one to step on the brake and gas peddle and the other to spray the carb cleaner while the car is reved up. We used the whole can. He removed one of the hose connector and spray the can in there. We tried to open the air filter but the engine will not run with the air filter open.

I am hoping that it will relearn and settle at the right rpm.

I don't know why dirty throatle plates affects the relearning of the computer.

Hope that helps.

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SORRY! GUYS! Idle Air Control Valve was the problem..... THATS IT! Just needed to be cleaned- it was covered in carbon! Should take you about 30-45 mins to fix :).

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SORRY! GUYS! Idle Air Control Valve was the problem..... THATS IT! Should take you about 30-45 mins to fix :).

why was your IACV not a problem before you disconnected the battery?

steviej

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SORRY! GUYS! Idle Air Control Valve was the problem..... THATS IT! Should take you about 30-45 mins to fix :).

why was your IACV not a problem before you disconnected the battery?

steviej

Just a guess- its probably because of the way they work- they allow a certain amount of air in and mine was covered in carbon. The computer over time had told it to open more to compensate for the carbon, however when I disconnected the battery, I assume that the computer was saying "hey, you cant open that far that fast! I am just idling!"

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SORRY! GUYS! Idle Air Control Valve was the problem..... THATS IT! Should take you about 30-45 mins to fix :).

why was your IACV not a problem before you disconnected the battery?

steviej

Just a guess- its probably because of the way they work- they allow a certain amount of air in and mine was covered in carbon. The computer over time had told it to open more to compensate for the carbon, however when I disconnected the battery, I assume that the computer was saying "hey, you cant open that far that fast! I am just idling!"

hate to tell you stevie,

Iam 99% sure 02& 03 do not not have a IACV

Scott

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SORRY! GUYS! Idle Air Control Valve was the problem..... THATS IT! Should take you about 30-45 mins to fix :).

why was your IACV not a problem before you disconnected the battery?

steviej

Just a guess- its probably because of the way they work- they allow a certain amount of air in and mine was covered in carbon. The computer over time had told it to open more to compensate for the carbon, however when I disconnected the battery, I assume that the computer was saying "hey, you cant open that far that fast! I am just idling!"

hate to tell you stevie,

Iam 99% sure 02& 03 do not not have a IACV

Scott

You are correct Scott, this year does not have a IACV.

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hate to tell you stevie,

Iam 99% sure 02& 03 do not not have a IACV

Scott

Scott,

I think you will find every fuel injectied car with a throttle body has some kind of idle air control valve or idle speed control mechanism.

The ES most certainly does.

steviej

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hate to tell you stevie,

Iam 99% sure 02& 03 do not not have a IACV

Scott

Scott,

I think you will find every fuel injectied car with a throttle body has some kind of idle air control valve or idle speed control mechanism.

The ES most certainly does.

steviej

On these cars, the throttle body is controlled by the ECM. The gas pedal sends a electronic signal, (actually two potentiometers, one starts at a low voltage, the other starts high). The ECM reads the position, and determines the appropriate position to place the throttle blade. Since the ECM has complete control of the throttle, there is no longer a need to have a separate control for the idle. The ECM just comands the throttle to open to a appropriate amount to set the idle speed. I assume from the previous posts, that the original problem was the throttle body had deposits, and they cleaned them off.

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hate to tell you stevie,

Iam 99% sure 02& 03 do not not have a IACV

Scott

Scott,

I think you will find every fuel injectied car with a throttle body has some kind of idle air control valve or idle speed control mechanism.

The ES most certainly does.

steviej

On these cars, the throttle body is controlled by the ECM. The gas pedal sends a electronic signal, (actually two potentiometers, one starts at a low voltage, the other starts high). The ECM reads the position, and determines the appropriate position to place the throttle blade. Since the ECM has complete control of the throttle, there is no longer a need to have a separate control for the idle. The ECM just comands the throttle to open to a appropriate amount to set the idle speed. I assume from the previous posts, that the original problem was the throttle body had deposits, and they cleaned them off.

Then tell me why it costs ~$300 for an Idle speed control for a 02-03 ES300 if the car does not have one according to you.

Click here.

steviej

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Well either my copy of Alldata is wrong, (which it has been before), or Park Place has labled the throttle control servo poorly. Unfortunately they do not post a picture of this. I do not have access to a 2002, so I am only going off manuals. Do you have access to one?

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Well either my copy of Alldata is wrong, (which it has been before), or Park Place has labled the throttle control servo poorly. Unfortunately they do not post a picture of this. I do not have access to a 2002, so I am only going off manuals. Do you have access to one?

I had both Lexus shop manuals for the 02 ES300 but they went with the sale of the vehicle last year.

steviej

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So far I have not found any further info on this. I have searched the schematics and mechanical drawings on Alldata, and there is no indication of a separate idle control on these cars. Since you used to own one do you recall, or did you ever have to work on the idle control valve? Everything I can find indicates that there is no separate idle control, and logically if the computer has complete controll over the throttle, there should be no need for a separate controll valve.

If anyone has access to a service manual, I would appreciate if you would could upload the relevent section. I am very interested in finding out what the actual setup is.

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When you removed the battery you erased all the learning values. It takes about 7 drive cycles to learn new ones. Depends on the distance of your daily drive and the number of times you turn the engine off and on, 7 drive cycles is 4 to 7 days. This is normal for all new generation vehicles.

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I had the same thing happen when I changed my battery. It took around 10 min of "assistive idling" and driving around for 15 min, but the ECM caught on. 

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Idle relearn

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In my case. It is owner " gotta-learn"! 

I disconnected the battery overnight. 

WTF moment. 

Thanks all

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