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Old 09-04-2016, 11:07 PM   #1
mattchyuuu
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Member#: 411061
Join Date: Jan 2015
Chapter/Region: RMIC
Location: Ogden, UT
Vehicle:
2004 WRX Limited

Default Cold Start Idle Issue

So I've been battling this weird issues for the past few weeks and haven't been able to figure it out.

I'm having a cold start issue where once I tap the gas after I first start the car ( like driving to a stop sign down the street and stopping ), my AFR will swing lean up to the 17-18 and back down to around 15 like normal. The car sounds lopey like I have cams when it swings lean. It will do this till the car comes to operating temp. There are no CELs. After the car warms up it drives great. My MPG have down quite a bit and when I come to a stop after the car is warmed up, my AFR will stay at about 14 for 30 seconds and go back up to in between 14.9-15.3. Also my car is hard to start sometimes taking quite a few more seconds to turn over.

Now I've went through and fixed minor boost and vacuum leaks that I found, thinking it was a boost or vacuum leak, but it didn't help. I'm thinking it might either be a bad MAF, so I cleaned mine and it still didn't do anything. Maybe it might be my tune? I'm not sure. Any insight would be appreciated.

My mods are:

Perrin Intake
Perrin Inlet
STI top mount
Catless Up pipe
Catless down pipe and exhaust
Lightweight crank pulley
Manual boost controller (tuner recommended)
DW 340lp fuel pump
Road tuned by Ed Hawkins at Fast Performance Tuning
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Old 09-05-2016, 01:33 AM   #2
hondaeater69
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Member#: 60324
Join Date: Apr 2004
Location: a pillow.
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changed your plugs lately?
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Old 09-05-2016, 02:17 AM   #3
mattchyuuu
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Member#: 411061
Join Date: Jan 2015
Chapter/Region: RMIC
Location: Ogden, UT
Vehicle:
2004 WRX Limited

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Yeah. Put the NGK iridiums in.
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Old 09-05-2016, 02:44 PM   #4
Horkus
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Join Date: Apr 2006
Chapter/Region: VIC
Location: Coquitlam
Vehicle:
2002 WRX wagon
WRB

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Fuel filter changed? Perhaps focus on fuel supply
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Old 09-05-2016, 03:05 PM   #5
wtdash
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Location: N. Idaho
Vehicle:
2002 WRX GG>>
2016 Focus RS

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Old 09-05-2016, 04:31 PM   #6
mattchyuuu
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Location: Ogden, UT
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2004 WRX Limited

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I changed the fuel filter about a year ago. But it was some brand from Autozone, not OEM
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Old 09-06-2016, 11:13 AM   #7
mattchyuuu
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Location: Ogden, UT
Vehicle:
2004 WRX Limited

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Just unplugged the MAF. Seems to run good if not better when it is unplugged. No bucking or hesitation. Does that mean a bad MAF?
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Old 09-08-2016, 01:05 AM   #8
205bug
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Have any way to log? You should get tactrix cable setup to see whats going on.
It does sound like a maf because you unplugged it and it ran better, typical failure point.
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