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Old 06-22-2010, 08:37 AM   #1
zavier
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2014 BRZ (DGM)

Default CEL P0506 problem

So I installed a switch next to the fog light switch on my 2.5i that connects the test connectors together because I was sick of going under the dash every 5min...it's been on the car for ~6mo now w/ no problem. The problem I am having now is I got the car washed the other day and the guys cleaning the inside of the car hit the switch while the car was on...every since the car has been throwing a P0506 "IDLE CONTROL RPM LOWER THAN EXPECTED".

I've cleared the CEL 3 times now but the car will not idle no matter what. The RPMs after warm up are around 400...after letting go of the gas they drop to like 345. After a reset it seems "fine" but the moment I go to move the car just shuts off unless I keep my foot on the gas...clutch engaged or in neutral the RPMs drop like a rock in a pool...I've never seen anything like it...It actually stalled today on my way to work (stuck in traffic) with the needle still around 2k rpm and the car turned off and the needle went down faster then a catholic school girl on prom night...

This is the switch...


This is a screen from LearningView


1st EDIT: (video)
Not sure what is wrong with the car still...btw this is a 5spd manual

At the 5sec mark I gave it gas and you can hear the car almost stall out
At the 11sec mark is when I turned the AC on to try and get the rpms to jump a bit (it sounds like they do but the car is still reporting under 500rpm at this point)
At the 18sec mark I pushed the clutch all the way to the floor, put it in 1st, and continued to keep the clutch all the way down...you can hear the car then hunt for a higher rpm...the car at this point reports 400-900rpm in the jump from low to high.

I think there is a vacuum leak somewhere but I'm not 100% sure...esp with the findings above...originally I thought that just turning the AC on should have made a difference but I was wrong...I accidentally found out about the clutch and 1st gear trick out of frustration...I've never heard of a car hunting for it's idle rpm that bad esp when the car is "in gear" but not engaged...I was under the impressing the car had no clue what to do till the clutch was released and gas was given, guess not :\

The car will not idle properly and just shut off at most stop signs / red lights when the car comes to a complete stop.
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Last edited by zavier; 06-28-2010 at 09:13 PM.
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Old 06-28-2010, 08:50 PM   #2
zavier
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ok so this got even weirder which makes me think it's a vacuum leak somewhere...

when the car wont hold idle (which right now it wont at all after gas is applied it just stalls) if i turn the AC on the RPMs do not move whatsoever...the funny thing though is that when the AC is on if I push the clutch all the way in and then put the car into 1st (or any gear for that matter...it's a MT btw) and continue to keep the clutch to the floor the RPMs jump up to 900-1000rpms but it hunts...it'll drop to 400rpm and then back up to 900rpm every second or so...I took a video and will be uploading it so maybe someone has some suggestions. I've pulled all the vacuum lines from the car and made sure they were snug, then i took the MAF sensor out and cleaned that and even replaced the rubber gasket ring because that was in bad shape too. Nothing seems to work...my next thing to try is replacing the air filter and cleaning the throttle body...if someone has anything to add please do I'm afraid with the car stalling out all the time I'm going to end up killing the starter and right now I don't need even more problems...
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Old 06-28-2010, 09:32 PM   #3
kero
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Anyway to remove that switch, wire back up correctly, reset ECU, let the car relearn idle correctly and see how it goes from their?

Obvioiusly it has something to do with that switch and the day they turned it on while the car was on or just coincidental.

I also read a few things on google and P0506 code and being MAF related either dirty or bad,etc.
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Old 06-28-2010, 09:54 PM   #4
zavier
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Quote:
Originally Posted by kero View Post
Anyway to remove that switch, wire back up correctly, reset ECU, let the car relearn idle correctly and see how it goes from their?

Obvioiusly it has something to do with that switch and the day they turned it on while the car was on or just coincidental.

I also read a few things on google and P0506 code and being MAF related either dirty or bad,etc.
I have removed the switch, reset, and let it sit at idle for 10-15min still no different...I have also used MAF cleaner on the sensor...but I'll give it another try tomorrow and see if something happens thanks
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Old 06-29-2010, 10:20 AM   #5
kero
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Any other mods on the car like intake and such? Also possible that maybe something got wet at the car wash or water go somewhere it shouldn't have?
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Old 06-29-2010, 10:36 AM   #6
zavier
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intake and cbe as far as engine ish goes...everything else is suspension work.
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Old 06-29-2010, 06:40 PM   #7
kero
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Hmmm, I wonder if the intake has anything to do with it? I am surprised no one has chimed in yet.
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Old 06-29-2010, 08:39 PM   #8
zavier
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as far as the intake i think i'm gonna finally convert to the hybrid intake...i just gotta get around to buying the ebay pipe
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Old 06-29-2010, 09:50 PM   #9
frankensubie
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these fly by wire cars don't learn idle after 10-15 minutes...it may require as much as 25-30 miles of driving for the car to return to idling normally after the ecu is reset... I.E. a full drive cycle or two
it's still a good idea to check for loose connections and or vacume leaks
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Old 06-29-2010, 09:59 PM   #10
zavier
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2014 BRZ (DGM)

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I've had this car for almost 3yrs now and I've reset the ECU more times then I can count and 10-15min is all it ever needed to relearn idle and I never had to actually drive it for idle to set properly...this is why I'm finding this hard to believe I can't find out what is wrong with it...
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Old 07-31-2010, 12:21 AM   #11
Mr Evolution
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Has anyone come up with the solution to fixing this low idle, want to pass inspection
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Old 08-06-2010, 08:51 AM   #12
BKRush
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I'm havin the same exact problem....let me know if you find out anything for sure
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Old 08-06-2010, 08:58 AM   #13
Jessekrs123
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Are there any vacuum hoses that go into the intake tube that you might have missed?
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Old 08-06-2010, 10:06 AM   #14
Mr Evolution
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Ok,

So here is what I did to solve the P0506 problem on a '04 Legacy 2.5L Drive by Wire BH5

Approximate 30-45 mins

Remove the negative terminal from the battery and step on the brake to discharge any power.

I took apart the complete intake (air box, MAF, throttle body, IAC)

For the Mass air Flow (MAF) sensor, I unscrewed the two retaining screws and sprayed CRC MAF cleaner on it and let it air dry. I had the sensor right side up (meaning the way it would sit if installed in the air box) This is so that no liquid goes into the sensor chip and only to clean the sensor its self.
Amazon.com: CRC 05110 Mass Air Flow Sensor Cleaner - 11 Wt Oz.:…Amazon.com: CRC 05110 Mass Air Flow Sensor Cleaner - 11 Wt Oz.:…

Next

I took apart the throttle body. *My car is drive by wire, so I just have to disconnect a wire. *I also did not remove or do anything to the actual throttle control (drive by wire)

I cleaned the throttle body by spraying on a towel and not directly to the throttle body. I cleaned flapper and all its carbon build up. I also sparyed the port where the IAC is plugged into (IAC removed before I sparyed it)

Re-assembled everything and started the car and gone is the CEL (Check Engine Light) and car never ran so nicely.

****Don't forget to reconnect the vacuum and heater hoses when you are doing the re-assembly of the throttle body and air boxes. ****

(I will be using Seafoam soon to clean through the vacuum line method. This is a just because I want to and the problem has already been corrected)

Hope this helps others to getting rid of the P0506 CEL code

God bless

Last edited by Mr Evolution; 08-06-2010 at 10:20 AM.
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Old 08-09-2010, 09:42 AM   #15
zavier
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2014 BRZ (DGM)

Default

Quote:
Originally Posted by Mr Evolution View Post
Ok,

So here is what I did to solve the P0506 problem on a '04 Legacy 2.5L Drive by Wire BH5

Approximate 30-45 mins

Remove the negative terminal from the battery and step on the brake to discharge any power.

I took apart the complete intake (air box, MAF, throttle body, IAC)

For the Mass air Flow (MAF) sensor, I unscrewed the two retaining screws and sprayed CRC MAF cleaner on it and let it air dry. I had the sensor right side up (meaning the way it would sit if installed in the air box) This is so that no liquid goes into the sensor chip and only to clean the sensor its self.
Amazon.com: CRC 05110 Mass Air Flow Sensor Cleaner - 11 Wt Oz.:

Next

I took apart the throttle body. *My car is drive by wire, so I just have to disconnect a wire. *I also did not remove or do anything to the actual throttle control (drive by wire)

I cleaned the throttle body by spraying on a towel and not directly to the throttle body. I cleaned flapper and all its carbon build up. I also sparyed the port where the IAC is plugged into (IAC removed before I sparyed it)

Re-assembled everything and started the car and gone is the CEL (Check Engine Light) and car never ran so nicely.

****Don't forget to reconnect the vacuum and heater hoses when you are doing the re-assembly of the throttle body and air boxes. ****

(I will be using Seafoam soon to clean through the vacuum line method. This is a just because I want to and the problem has already been corrected)

Hope this helps others to getting rid of the P0506 CEL code

God bless
Yea someone suggested to me that I try and clean the TB as well as the IACV...that's on my list of things to check...thanks
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Old 08-09-2010, 10:48 AM   #16
Mr Evolution
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good luck with it. My car is running no problems for two weeks now and huge noticeable power increase
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Old 08-09-2010, 06:42 PM   #17
RaceFaceXC
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Quote:
Originally Posted by frankensubie View Post
these fly by wire cars don't learn idle after 10-15 minutes...it may require as much as 25-30 miles of driving for the car to return to idling normally after the ecu is reset... I.E. a full drive cycle or two
it's still a good idea to check for loose connections and or vacume leaks
Quote:
Originally Posted by zavier View Post
I've had this car for almost 3yrs now and I've reset the ECU more times then I can count and 10-15min is all it ever needed to relearn idle and I never had to actually drive it for idle to set properly...this is why I'm finding this hard to believe I can't find out what is wrong with it...
DBW subaru's take about 8-10 mins to settle the idle trims down after an ECU reset. the accel pedal and A/C-defrost must not be touched during this first start after a reset for the 8-10 mins. If a reset is done and driven immediately, it can take several hundred miles to get the idle rock solid.
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Old 08-10-2010, 08:51 AM   #18
zavier
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2014 BRZ (DGM)

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Quote:
Originally Posted by RaceFaceXC View Post
DBW subaru's take about 8-10 mins to settle the idle trims down after an ECU reset. the accel pedal and A/C-defrost must not be touched during this first start after a reset for the 8-10 mins. If a reset is done and driven immediately, it can take several hundred miles to get the idle rock solid.
Yea I know that...what's why I'm having a hard time believing all of a sudden (after 3yrs) my car is no longer following that rule of thumb...which leads me to believe something is "broke" somewhere...I've checked all vacuum lines, cleaned the maf, replaced the maf gasket because it broke a few months back but was still holding together, checked the spark plugs...at this point it's time to check the TB/IACV
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