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Old 03-20-2009, 08:58 PM   #1
TurboQueef
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Default Idle varies like vaccum leak but not !

Hi,

I am running a RAW/Axis block with KS Tech 83mm CAI, APS turbo inlet, FP Red, 850 DW injectors, Perrin EL headers.

Every so often when I come to a stop the RPM's will increase to 2K or so then settle in at 1K (as set via ECU). It acts like a vacuum leak but I don't see any signs of this on the gauge and I can't reproduce it by probing the vacuum lines when at idle.

Anyone else have a this problem?

Thanks,

Jeff B
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Old 03-21-2009, 04:16 AM   #2
jigga
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are you running a standalone ECU? Some are setup to give you a fast idle as you come to a stop in order to stabilize the engine and prevent stalling. Usually though, the idle settles down to normal as soon as you stop, but for those last 1 or 2 mph, the idle stays a tad higher than usual.
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Old 03-21-2009, 09:07 AM   #3
TurboQueef
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Quote:
Originally Posted by jigga View Post
are you running a standalone ECU? Some are setup to give you a fast idle as you come to a stop in order to stabilize the engine and prevent stalling. Usually though, the idle settles down to normal as soon as you stop, but for those last 1 or 2 mph, the idle stays a tad higher than usual.
Thanks for the feedback. I am running the stock ECU. I can relate to what you are saying it seems like the ECU is trying to stabilize the engine but in some cases, it holds the idle up to long.
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Old 03-21-2009, 09:44 AM   #4
Tap
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Sticking BOV or IAC
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Old 03-21-2009, 10:37 AM   #5
TurboQueef
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Quote:
Originally Posted by Tap View Post
Sticking BOV or IAC
Good lead.. can you tell me where the Idle Air Control valve is located (is it that stupid white thing hooked to the inlet tube hose?)

Thanks,

Jeff B
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Old 03-21-2009, 12:11 PM   #6
Tap
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sorry, the 05 doesn't have a IAC, do you have any CEL codes?
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Old 03-21-2009, 12:26 PM   #7
TurboQueef
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Quote:
Originally Posted by Tap View Post
sorry, the 05 doesn't have a IAC, do you have any CEL codes?

It never throws a CEL when the idle acts up but it just recently offered up a P2096 as I was cruising on the highway.

Last year I randomly got P2100 a few times.

Thanks

Jeff B
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Old 03-21-2009, 06:28 PM   #8
Tap
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p2100 has to do with the "Throttle Actuator Control Motor Circuit" which could indicate issues with the DBW throttle body. Even if it is not throwing codes now, check the connector, pins and the wires make sure they are not damaged (cracked connector, worn spots on the harness, bent damaged pins, etc). That circuit is part of the idle control. That all being said, I tend to have a high idle every once in awhile (non-DBW). A quick trip into high boost and slamming the throttle shut fixes it for a couple of days.

Last edited by Tap; 03-21-2009 at 06:38 PM.
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Old 03-22-2009, 09:21 AM   #9
andya
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The P2100 code is caused 90% of the time by the throttle control relay which is mounted with the fuel pump and ASD relay set.. Pass side kick panel by the glove box. It is a round metal relay with the black wire connector.
It is possible for your other code to be set as well if the points are burnt causing a low ripple voltage to the MAP sensor.
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Old 03-22-2009, 09:27 AM   #10
TurboQueef
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Quote:
Originally Posted by andya View Post
The P2100 code is caused 90% of the time by the throttle control relay which is mounted with the fuel pump and ASD relay set.. Pass side kick panel by the glove box. It is a round metal relay with the black wire connector.
It is possible for your other code to be set as well if the points are burnt causing a low ripple voltage to the MAP sensor.
Good lead... by chance do you know the part number for this relay? It may be worth a try to just replace it.

Thanks,

Jeff B
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Old 03-22-2009, 09:35 AM   #11
andya
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I can look it up for you at work tomorrow, but I just swapped the relays with the fuel pump since they are the same and the pump does not use as many amps to operate.... Just to be sure.
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Old 03-22-2009, 09:48 AM   #12
TurboQueef
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Quote:
Originally Posted by andya View Post
I can look it up for you at work tomorrow, but I just swapped the relays with the fuel pump since they are the same and the pump does not use as many amps to operate.... Just to be sure.
Good idea... I will do that this AM and test it out.

Thanks a lot for the help!!!
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Old 03-22-2009, 10:25 AM   #13
TurboQueef
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Quote:
Originally Posted by TurboQueef View Post
Good idea... I will do that this AM and test it out.

Thanks a lot for the help!!!
I just swapped them out... the part number is ink stamped on each relay:

DENSO # 056700-5260

I will post update as to it working later today.

Thanks again for the lead

Jeff B
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Old 03-23-2009, 05:23 AM   #14
TurboQueef
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Quote:
Originally Posted by andya View Post
I can look it up for you at work tomorrow, but I just swapped the relays with the fuel pump since they are the same and the pump does not use as many amps to operate.... Just to be sure.
I put 200 miles on it yesterday (after swap of relays) and the idle was much better but... It still acts a bit strange at times just not as pronounced as before. I would say there is still something causing it to raise the idle abnormally during slow down. I will update this thread if anything else materializes.

Thanks,

Jeff B
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Old 03-23-2009, 08:00 AM   #15
andya
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Quote:
Originally Posted by TurboQueef View Post
I put 200 miles on it yesterday (after swap of relays) and the idle was much better but... It still acts a bit strange at times just not as pronounced as before. I would say there is still something causing it to raise the idle abnormally during slow down. I will update this thread if anything else materializes.

Thanks,

Jeff B
I totally forgot to tell you to clear memory. The ECU has a tendency to learn bad habits.
The SOA part# for the relay.... 82501AA130

Last edited by andya; 03-23-2009 at 10:13 AM.
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Old 03-23-2009, 06:37 PM   #16
TurboQueef
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Quote:
Originally Posted by andya View Post
I totally forgot to tell you to clear memory. The ECU has a tendency to learn bad habits.
The SOA part# for the relay.... 82501AA130
O... I should have thought of that too... will give it a try next time out.

Thanks,

Jeff B
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Old 04-26-2009, 11:24 PM   #17
07wrx4life
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Hey I just searched up this thread as I too have this same problem, I randomly get a P2100 CEL code while driving usually under vacuum.
The only problem I have with the car Is an Idle Issue when the car Is warm, I will shut off the car for a few mins come back to It start It and It will shake violently like It's missing or something, No CEL's just shakes and Idles crappy. Drive the car for about 5 seconds come to a stop sign and Its completly normal again. Anyone this these 2 are related? I will order up a SOA Part# 82501AA130 tomorrow morning but I wanted to see what you guys think.

Thanks
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Old 04-27-2009, 05:14 AM   #18
TurboQueef
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Quote:
Originally Posted by andya View Post
I totally forgot to tell you to clear memory. The ECU has a tendency to learn bad habits.
The SOA part# for the relay.... 82501AA130
I reset the ECU and have put 1000 mile on the car. The P2100 error has not re-occurred and the idle was good for the first 300 miles or so but it seems the ECU learns something in the 300 miles that makes the idle go strange again. I am starting to think it has to do with the 83mm MEGA MAF. I have always struggled to get the intake calibration set correctly at 2500 RPM and I think the ECU is not happy learning its way around that.

Jeff B
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