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Old 01-10-2010, 09:06 PM   #1
MRX WRX
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Default surging idle

ok so i have tried EVERYTHING to try and get the surging to go away. its not bad but it drives me crazy! strange thing is that it did not do it until i put a header on yesterday?!?! anyway here is the setup: BC 272 cams, modded stock injectors (STI), ported heads, base FP is 50psi and i run on e85. the car surges from about 750 up to around 1050. adjusted MAF at that range,timing and everything and nothing changes at all??? i have set the base at 800-900 and 1000 and still does the same. i also have the idle timing (and all other relevant tables ) set at 15* and for some reason it fluctuates between 10* and 22* and teh AFR goes from about 13.5 to 16.1 while its surging. trim values stay around -8 to +3. while its surging and will show trim learning at -.78
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Old 01-10-2010, 10:49 PM   #2
freetors
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kinda sounds like your IACV might be going out. mine had similar symptoms. If it is the IACV it WILL get worse.
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Old 01-10-2010, 11:43 PM   #3
van_dutch
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Quote:
Originally Posted by freetors View Post
kinda sounds like your IACV might be going out. mine had similar symptoms. If it is the IACV it WILL get worse.
Drive by wire (the 2.5L engine) means no IACV.

Last edited by van_dutch; 01-10-2010 at 11:46 PM. Reason: wording.
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Old 01-14-2010, 11:07 AM   #4
tekfoc
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try cleaning your mass airflow sensor with rubbing alcohol also make sure the o ring is not damaged .
while their check carefully for intake leaks -hoses-clamps -and so on .
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Old 01-14-2010, 05:36 PM   #5
notraceready
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My idle surges sometimes but I just attribute it to my tial bov.
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Old 01-15-2010, 09:20 AM   #6
MRX WRX
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im running blow thru so the BOV wont make a difference. but i am gona try cleaning the MAF sensor today and that may fix it.
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Old 01-15-2010, 09:42 AM   #7
nitroinsane
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while installing your header did you hit anything? check engine light? my wrx had a surge that drove me nuts. it ended up being a vac leak.
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Old 01-16-2010, 01:09 PM   #8
MRX WRX
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checked for vacuum leaks this morning and that was not it. so im gonna clean the sensor in a bit and se what that does!
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Old 01-22-2010, 01:37 PM   #9
MRX WRX
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ok, i am in need of some serious help now!! i have checked everything, cleaned sensor ,replaced 02 and it still surges. what is really killing me is that with the 02 unplugged it idles perfect but as soon as you plug it in it starts to surge, i have changed all settings and it still does the same thing??? i have even turned off closed loop completely (i think). with soooo many tables i must be missing something so could someone tell me how to eliminate closed loop during idle?
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Old 01-27-2010, 06:32 PM   #10
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So if it's not the o2 sensor then maybe it's the reading that the o2 sensor is getting. Like a small exhaust leak before the sensor. I think at idle air can get sucked in through a small leak, making the o2 read lean. I'm trying to figure out the same problem and I've checked for vac leaks. What's your learning View look like?
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Old 01-28-2010, 09:10 AM   #11
MRX WRX
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well interesting enough after changing EVERY parameter in the accesstuner and getting zero changes. i took the commander and raised the idle to 975 and the surging went away. what i dont understand is that i changed the idle settings(all tables) in the tuner and the idle did not change at all. it seems like something is not working. my learning numbers while surging were anywhere from -5 to -15 NO MATTER WHAT I CHANGED IT STAYED THE SAME????? i have the idle tables set at 1k and the idle still would drop down to 750, like stock. another issue im having is that no matter what numbers i put in the fuel table im still getting over 100% IDC. and i have scaled the MAF numbers down too and its not changing either??? i must have something way off although the car runs great, trims are all within 5%. i just cant seem to get anything to change.
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Old 01-28-2010, 11:03 AM   #12
tekfoc
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Call cobb ! could be a software glitch .
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Old 03-22-2011, 09:59 PM   #13
Rizzo314
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My car just started doing the EXACT same thing. I thought I had it figured out when I found a tear in the turbo inlet, but I just spent all night replacing it and it still does the same thing.

AFRs bounce between 12.7 - 15.5, both at idle and also when driving. I am totally confused about this. Did you ever figure it out?
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