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Old 11-01-2007, 10:54 PM   #1
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Default car runs better with tps sensor umplugged

I have been fighting a rough idle in closed loop and decided to disconnect the tps sensor to see how the car would act and it idle's smoother and the get up and go is much better. I got a new tps sensor and the car ran better for a while and then the idle issue came back. What happens is in closed loop only when coming to a stop at a light the idle will go down a little so the engine will idle rough. It will stay like this for maybe 5 secs and then rev back up and just idle a little rough. I unplugged the sensor again the problem went away and the power difference is up in a good way. Is there a special procedure on replacing this sensor? Do I have to test the voltage and adjust or what?
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Old 11-02-2007, 12:07 AM   #2
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Is the car throwing any DTCs? Do you have access to a scan tool? If so, check the TP % at idle. It sounds to me like it's not reading 0%. Anything greater then 0% at idle, the PCM will see as a "non-idle" condition and calculate airflow accordingly. During this situation, the correct idle tables will not be used which would cause the rough idle your describing. I don't know why this would effect power elsewhere, but it has to be related. Below is a link to a short write-up I did on checking the voltage at the TPS and resetting it. Follow the steps and see if it helps.

http://www.ls1tech.com/forums/showpo...24&postcount=2
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Old 11-02-2007, 09:36 AM   #3
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Quote:
Originally Posted by Shallow Bay View Post
Is the car throwing any DTCs? Do you have access to a scan tool? If so, check the TP % at idle. It sounds to me like it's not reading 0%. Anything greater then 0% at idle, the PCM will see as a "non-idle" condition and calculate airflow accordingly. During this situation, the correct idle tables will not be used which would cause the rough idle your describing. I don't know why this would effect power elsewhere, but it has to be related. Below is a link to a short write-up I did on checking the voltage at the TPS and resetting it. Follow the steps and see if it helps.

http://www.ls1tech.com/forums/showpo...24&postcount=2
That's what mine was doing. TP% was 25 at idle. I reset the tps and it's fine now.
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Old 11-02-2007, 10:22 AM   #4
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At idle the throttle % is 0 as it should be. I tested the tps a while ago with a multimeter and it tested fine though. Weird I say. Also no codes thrown.
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Old 11-02-2007, 05:13 PM   #5
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Another thing I noticed is if I turn the car off and restart the rough idle goes away for a while. Today the idle was fine for 25-30 mins of driving then started to idle bad.
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Old 11-03-2007, 10:16 AM   #6
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Hmm not to hijack but I was under the impression on modded cars tps would be more than zero? mines is at 8 at idle.... something I need to look into? btw idles fine.
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Old 11-03-2007, 10:16 AM
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