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Old 09-11-2016, 11:18 PM   #1
Wheel Man
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Join Date: Jul 2007
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Crystal Black Silica

Default Fuel pump issue? Or coils?

Okay, here's what I've got.

I have an 02', which until today, was 100% bone stock.

I was having issues under WOT in 2nd and 3rd gear around 4-5k RPM, where there would be a heavy hesitation. This seemed only prevalent at full operating temperature. (For the sake of getting as much info as possible, I did a couple single pulls when the car was cooler, and it seemed to be less of an issue)

I have replaced the MAF, A/F, and 02 sensors at this point. No change.

Thought, maybe just a bad map on the ECU from non 91 octane runs from the previous owner, so I reset the ECU, and cleaned the plugs.

I added a TBE and an Access-port today, to see if I could get the issue to stop.

New info. When running an Economy map, (w/g spring only) I have ZERO hesitation, and smooth power. Stock, Stage 1 and 2, the bucking at now 3500-5000 rpm is grossly more active.

I am assuming that the fuel pump is getting weak based on the fact that the problem grows in relation to boost/fuel needs.

I just wanted a second opinion. Car's well cared for, but was never really put to it's paces, so I'm finding little issues here and there.

Thanks in advance, I greatly appreciate you guys/gals,

-Rick
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Old 09-13-2016, 03:46 AM   #2
oaklandish_WRX
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Location: Ostinato Rigore
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MBP LongRoof

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Would you call it "oscillating" under boost? Slow, periodic surging and falling off, repeating?

Also, don't run an OTS AP map that does not correspond to your precise mods...recipe for disaster. But, since you have the AP, log and post on googledocs, etc. so we can review. Still have the OEM catted UP?
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Old 09-13-2016, 10:53 AM   #3
Wheel Man
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Its sharp, immediate loss of power. Using the OTS economy map, under full load theres no issue at all. Stock map or higher (Im stage 2 capable) the problem worsens in the higher maps. Still stock uppipe. (the issue was prevelant when completely stock as well)

I'll get a log done up hopefully tonight after work.

Last edited by Wheel Man; 09-13-2016 at 01:35 PM.
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Old 09-13-2016, 02:45 PM   #4
oaklandish_WRX
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Quote:
Originally Posted by Wheel Man View Post
Its sharp, immediate loss of power. Using the OTS economy map, under full load theres no issue at all. Stock map or higher (Im stage 2 capable) the problem worsens in the higher maps. Still stock uppipe. (the issue was prevelant when completely stock as well)

I'll get a log done up hopefully tonight after work.
UP's gotta go, regardless...but you knew that. Most folks here wouldn't call a catted UP "stage 2 capable". Post logs then people can make slightly better guesses.
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Old 09-13-2016, 03:07 PM   #5
Wheel Man
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Right-o
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Old 09-13-2016, 04:01 PM   #6
Fierysun
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Did you change to a new fuel filter?
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Old 09-14-2016, 12:00 AM   #7
Wheel Man
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Crystal Black Silica

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Ok, I'm trying to get my log uploaded (first time, so bear with me). During the run (a quick 3rd gear pull) I noticed I got a flashing CEL this time. Misfire Cyl 3. (this is was on the married stock map). I went through my paperwork from the previous owner, it seems he had a similar issue. His shop replaced coil #1 with coil #4, and the problem went away (obviously not for very long).

*Side note* Why would switching one pack to another location fix an issue.... That sounds weird to me...
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Old 09-14-2016, 02:48 AM   #8
subaru_gc8
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i vote coil
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Old 09-16-2016, 04:01 PM   #9
subiespeed78
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is the car misfiring at all?
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Old 09-22-2016, 12:38 AM   #10
Wheel Man
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13 STI
Crystal Black Silica

Default

Great news! I pulled the coils and plugs out. (the plugs were replaced by the previous owners mechanic about 4k miles ago....)

The plugs were for the N/A, and were gapped at .40

Replaced the plugs, gapped at .30, and replaced coils. Car runs bomb diggity.
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