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Old 06-23-2011, 09:54 PM   #1
Mertzz
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Default 05 2.5 RS low idle

Last week my car started to idle very low almost like it was cammed up. Did a tune up then wouldnt idle at all. So i reset the ecu and still wouldn't idle and then i unplugged the throttle body connector fired up and idled fine. But no throttle response though since it was unplugged. Is it possible to clean the throttle sensor and the servo and what to use if i can?
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Old 06-24-2011, 12:04 AM   #2
Bluefoton
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Location: Quebec, QC
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2008 2.5i-hatch -
now with a HID retrofit

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No CEL, just bad idle? Could be the MAF sensor.. or the idle air control valve... or a vacuum leak...
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Old 06-24-2011, 12:47 AM   #3
rhino6303
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05 Legacy GT RBP

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Can't be idle air control valve, as 2005+ does not have one.
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Old 06-24-2011, 11:35 AM   #4
Mertzz
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Well the cel was on before the problem started, because of the rear O2 sensor throwing a code, but it ran fine and all looked clear on the scanner. My brother and I have checked for leaks and couldn't find any. The odd part was after checking all the sensors while it was idling barely nothing changed until with unplugged the throttle body and it started and idled find. That's another thing I forgot to mention it starts hard and usually have to tap the gas a little. But with it unplugged it started and idled with only a slight surge. I'm gonna hook the scanner up today to see if it is throwing. Any other codes besides the o2 one
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Old 06-24-2011, 01:49 PM   #5
RaceFaceXC
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Anything changed from stock on the engine, intake,exhaust, etc? What was involved in the "tune up"?
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Old 06-24-2011, 04:50 PM   #6
Mertzz
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I have an injen intake, Borlaug unequal length headers and full exhaust. I put new plugs in and the wires I was going to get but they didn't have, but they don't look bad at all. I bought injector cleaner to but I didn't put that in yet either
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Old 06-24-2011, 04:53 PM   #7
Mertzz
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Borla* stupid auto correction on my iPhone
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Old 06-24-2011, 08:02 PM   #8
RaceFaceXC
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Clean the maf sensor yet? What kind of filter on the intake- the one that came with the injen? Unplugging the tb might disable lots of things like o2 sensors, maf, etc so it would just run off the ecu maps in "limp mode" so to speak. You should try plugging the tb back in and unplugging the maf sensor and start it, see how it idles. Don't drive out like that, though. With that intake and maf disabled your fueling will probably be ****.
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Old 06-24-2011, 10:31 PM   #9
slayers_x
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this happened to me before. how many miles do you have on your car? I changed the front o2 sensor and everything went away.
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Old 06-24-2011, 11:46 PM   #10
Mertzz
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It only has 57,000. And yes it is the intake that came with( its clean). We cleaned the maf twice now and it hasn't helped at all. Does anyone know what the throttle position sensor percentage reading should be while hooked to the diagnostic reader. Mine was running at 17% closed and 79% wide open throttle. Sometimes when its unplugged and plugged back in it wont read the throttle response from the pedal anymore. But when resetting the ecu it works again
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Old 06-25-2011, 12:28 AM   #11
formula91
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Sounds like the sensor might be going bad.
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Old 06-25-2011, 03:11 AM   #12
williaty
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Vehicle:
2005 2.5RS Wagon
Regal Blue Pearl

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Your throttle positions are bad.

Idle takes 3-5% on that car and WOT should obviously be 100%.

Plug everything back together properly. Reset the ECU. Turn the key to ON (DO NOT touch the gas or try to start the car). Let it sit with the key ON for 20 seconds. DO NOT TOUCH THE GAS PEDAL. Start the car. DO NOT TOUCH THE GAS PEDAL. Let it idle for 10 minutes. DO NOT TOUCH THE GAS PEDAL. Turn the key to OFF. Wait 10 seconds. Turn the key to ON (but don't start the car). Monitor the throttle position using the scanner while you slowly move your foot from no throttle to the carpet and back a couple of times. If it doesn't go from min (0% or the 3-5% for idle depending on your ROM) all the way to 100%, you have a problem. Compare this to the accelerator pedal position sensor (again using the scanner). The ACPS should run from 0% to 100% smoothly.

If the ACPS moves from 0% to 100% smoothly but the TPS doesn't track it, the throttle body needs replaced (sensor and motor are integral to it). If the ACPS doesn't move smoothly from 0% to 100%, the accelerator pedal assembly needs replaced (sensor is integral to the assembly).
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