High Idle speed after starting. Have to restart - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

 
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post #1 of 8 (permalink) Old Oct 3rd, 01, 12:57 AM Thread Starter
 
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Location: Kissimmee Florida. USA
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My 1998 LS1 Camaro Z-28 Idles up to 2500 to 3000 rpm's sometimes when you start the car. I shut down the engine and restart. After several attempts (and a few well-chosen words), the idle drops in line. What should I look for? The throttle linkage is fine.
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post #2 of 8 (permalink) Old Oct 4th, 01, 02:56 AM
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John
 
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I am not very well versed with the newer models unfortunately. Welcome to the site all the same! I hope that someone can help you. The only thing that really comes to my mind would be the choke, but I don't know how the choke works on an LS1. Good luck.
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post #3 of 8 (permalink) Old Oct 4th, 01, 03:49 PM
 
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Ok dumb question.

Does it idle up to 2500-3000 and then drop back off after a short period of time?

The only thing I have close to you year is my 95 truck. When I start is it will idle up to 1500-2000 and drop back off. I always thought it was the electronically controlled choke or something in the fuel injection system being on at start up and then cutting off if not needed.

Thanks for your time.
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post #4 of 8 (permalink) Old Oct 7th, 01, 03:18 PM Thread Starter
 
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<BLOCKQUOTE>quote:</font><HR>Originally posted by 68moneypit:
Ok dumb question.

Does it idle up to 2500-3000 and then drop back off after a short period of time?

The only thing I have close to you year is my 95 truck. When I start is it will idle up to 1500-2000 and drop back off. I always thought it was the electronically controlled choke or something in the fuel injection system being on at start up and then cutting off if not needed.

Thanks for your time.
<HR></BLOCKQUOTE>

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post #5 of 8 (permalink) Old Oct 7th, 01, 03:29 PM Thread Starter
 
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<BLOCKQUOTE>quote:</font><HR>Originally posted by 68moneypit:
Ok dumb question.

Does it idle up to 2500-3000 and then drop back off after a short period of time?

The only thing I have close to you year is my 95 truck. When I start is it will idle up to 1500-2000 and drop back off. I always thought it was the electronically controlled choke or something in the fuel injection system being on at start up and then cutting off if not needed.

Thanks for your time.
<HR></BLOCKQUOTE>


Thanks for taking the time to reply to my question. It does rev up at the start but does not drop back. I have to shut it off and restart the car. Sometimes several times. I checked the linkage when this happens and it is in the correct position. There is a solenoid on the air intake. When I disconnect it, it makes no difference. I think I just answered my own question. I think I will disconnect it when it is running ok. Well if I can't figure it out I will do the dirty and let someone else look at it. I hate the thought of someone else touching it. Kind of like when my wife asks, Can I drive your car? Gives me the willys just thinking about it. Thanks again, Michael
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post #6 of 8 (permalink) Old Oct 7th, 01, 03:39 PM
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The Idle Air Control valve, or IAC controls the idle. All it is is a motor with pintle the at contracts and extends varying the amount of air that bypasses the throttle plate (which is closed at idle). when cold, the pintle in contracted to open the passage fully. This allows a lot of ait into the engine. The Mass Airflow Sensor(MAF) or Manafold Absolute Pressure sensor(MAP)..not sure which one your car uses, but serve the same purpose, senses the amount of air flowing entering the engine. The ECU or (computer) Uses the info form the MAF, or MAP and determines the amount of fuel to be delivered...knowing this, you may have a faulty IAC valve, A fauly MAF or MAP that is sending wrong info to computer, or a faulty computer (not very likly, but possible) First thing to do is to determine wether the computer has a stored code. This will make diagnosis much easier.So..all I can offer, since I cant actually see the car is that you find a shop that can determine if there are any codes in the system...Not much help, I know. there are simply too many possibilities to pinpoint the cause.
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post #7 of 8 (permalink) Old Oct 7th, 01, 03:50 PM Thread Starter
 
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<BLOCKQUOTE>quote:</font><HR>Originally posted by cavemate:
The Idle Air Control valve, or IAC controls the idle. All it is is a motor with pintle the at contracts and extends varying the amount of air that bypasses the throttle plate (which is closed at idle). when cold, the pintle in contracted to open the passage fully. This allows a lot of ait into the engine. The Mass Airflow Sensor(MAF) or Manafold Absolute Pressure sensor(MAP)..not sure which one your car uses, but serve the same purpose, senses the amount of air flowing entering the engine. The ECU or (computer) Uses the info form the MAF, or MAP and determines the amount of fuel to be delivered...knowing this, you may have a faulty IAC valve, A fauly MAF or MAP that is sending wrong info to computer, or a faulty computer (not very likly, but possible) First thing to do is to determine wether the computer has a stored code. This will make diagnosis much easier.So..all I can offer, since I cant actually see the car is that you find a shop that can determine if there are any codes in the system...Not much help, I know. there are simply too many possibilities to pinpoint the cause.<HR></BLOCKQUOTE>
Thank you! I will take this information and have a read out done. I will post what was found and what was done to correct the problem for anyone's future reference. Thanks again


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post #8 of 8 (permalink) Old Oct 10th, 01, 01:24 PM Thread Starter
 
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Here is the skinny. I decided to get an obd2 code reader. The day I went to get one, I noticed The car would turn over (start) As if there was too much compression. My clock would reset to 1:00 at times. Trying to start the car sometimes the voltage meter would not show a full charge. I decided to do an electrical check first. I started the car and checked the voltage at the battery. I got 14 vdc. I shut the car off and read the voltage. 11 volts and the car started fine. So, I started the car several time with the AC on. The car idled up to 3000RPM's. I shut the car down and rechecked the voltage. 10 vdc. I had one of my employees check the voltage as I started the car. It dropped below 8 vdc. I replaced the battery. The problem stopped. It runs fine now. New problem. You see nothing goes as planned for me. I can't use my radio. I have to go to a dealer to set the code for it. I forgot my code. That's ok, I drive too fast to hear it anyway. Thanks all that replied. I hope this will help someone else in the future.

<BLOCKQUOTE>quote:</font><HR>Originally posted by cavemate:
The Idle Air Control valve, or IAC controls the idle. All it is is a motor with pintle the at contracts and extends varying the amount of air that bypasses the throttle plate (which is closed at idle). when cold, the pintle in contracted to open the passage fully. This allows a lot of ait into the engine. The Mass Airflow Sensor(MAF) or Manafold Absolute Pressure sensor(MAP)..not sure which one your car uses, but serve the same purpose, senses the amount of air flowing entering the engine. The ECU or (computer) Uses the info form the MAF, or MAP and determines the amount of fuel to be delivered...knowing this, you may have a faulty IAC valve, A fauly MAF or MAP that is sending wrong info to computer, or a faulty computer (not very likly, but possible) First thing to do is to determine wether the computer has a stored code. This will make diagnosis much easier.So..all I can offer, since I cant actually see the car is that you find a shop that can determine if there are any codes in the system...Not much help, I know. there are simply too many possibilities to pinpoint the cause.<HR></BLOCKQUOTE>

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