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10-03-2013, 01:33 PM | #1 |
Scooby Newbie
Member#: 329793
Join Date: Aug 2012
Location: South Point, Ohio
Vehicle:2002 WRX PSM |
engine stutter when under load
Hey folks. Ive got an interesting issue. My car drives wonderfully when normal driving is taking place- but then the pedal is applied, 70% of the time it stutters and sputters and backfires at around 1/2 throttle. In neutral, it revs fine and fast, no issue.
I have, in my 02 wrx, a jdm ej207 with the following mods: *16g turbo upgrade, 18psi (with the issue it rarely breaches 10psi) *Perrin silicone turbo inlet with short ram air intake *big tmic with silicone hoses *550cc yellow side feed injectors *Walbro 255lph fuel pump *fully catless exhaust *race header *3 inch catless bellmouth dp *3 inch catless stainless mandrel bent exhaust *jdm tgvless intake on phenolic spacers *12lb flywheel *Grimmspeed 3 port boost controller *probably other things I cant remember The system has been boost leak tested, so thats not the issue. Any ideas or input or suggestions would be wonderfully appreciated! Im stuck in a rut and out of ideas. Its also running a Cobb ap v2, btw. Thanks for reading!
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10-03-2013, 01:35 PM | #2 |
Scooby Specialist
Member#: 357718
Join Date: May 2013
Chapter/Region:
MWSOC
Location: Springfield Illinois
Vehicle:2007 WRX WRB |
Are you running a custom tune or just a cobb off the shelf map?
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10-03-2013, 01:49 PM | #3 |
Scooby Newbie
Member#: 329793
Join Date: Aug 2012
Location: South Point, Ohio
Vehicle:2002 WRX PSM |
Custom tune from iaperformance. Also I cant do a wot test run bc when I roll into wot it starts stuttering really bad. Also, when I have the Cobb plugged in...the car seems to run much worse.
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10-03-2013, 02:28 PM | #4 |
Scooby Specialist
Member#: 279525
Join Date: Apr 2011
Chapter/Region:
Tri-State
Location: QUEENS NY
Vehicle:06 Fxt |
Whats the spark plug situation like? Ever throw any check engine light codes?
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10-03-2013, 05:27 PM | #5 |
Scooby Newbie
Member#: 329793
Join Date: Aug 2012
Location: South Point, Ohio
Vehicle:2002 WRX PSM |
Bank one running lean code, but thats it. Plugs are brand new ngk iridium 9s
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10-04-2013, 09:29 AM | #6 |
Scooby Newbie
Member#: 329793
Join Date: Aug 2012
Location: South Point, Ohio
Vehicle:2002 WRX PSM |
Bump for insight
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10-04-2013, 09:47 AM | #7 |
Scooby Specialist
Member#: 321409
Join Date: May 2012
Chapter/Region:
SWIC
Location: Arrey, NM
Vehicle:2003 Big Effing Van 7.3L powerstroke diesel |
Bad MAP sensor (Manifold Absolute Pressure) is my guess.
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10-04-2013, 09:57 AM | #8 |
Scooby Newbie
Member#: 329793
Join Date: Aug 2012
Location: South Point, Ohio
Vehicle:2002 WRX PSM |
Care to elaborate as to why (
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10-04-2013, 09:59 AM | #9 |
Scooby Specialist
Member#: 307359
Join Date: Jan 2012
Chapter/Region:
South East
Location: Atlanta,GA
Vehicle:'05 STi Stage II OBP |
Bad O2 sensor?
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10-04-2013, 10:23 AM | #10 |
Scooby Specialist
Member#: 279525
Join Date: Apr 2011
Chapter/Region:
Tri-State
Location: QUEENS NY
Vehicle:06 Fxt |
Yes was leaning towards bad o2 after what u stated. J
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10-04-2013, 10:46 AM | #11 |
Scooby Specialist
Member#: 321409
Join Date: May 2012
Chapter/Region:
SWIC
Location: Arrey, NM
Vehicle:2003 Big Effing Van 7.3L powerstroke diesel |
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10-04-2013, 10:50 AM | #12 |
Scooby Newbie
Member#: 370067
Join Date: Oct 2013
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Major Problem: 2011 WRX upgraded to AccessPort v3
2011 WRX
I bought it with 20k miles on it. Car already had invidia catless dp and magnaflow exhaust. Had previously been tuned with an older accessport. However the ap did not come with the car. *Note: at this point the car runs really well and I have put almost 1,000 mile on it with no issues. So I bought a v3 and installed it the other night. Now no matter what OTS map I run, the fuel cuts at 2psi boost. Of course I have now lost the map that was on there originally. I uninstalled the ap and tried driving around with the stock ecu setting. It still fuel cuts around 5-10 psi. Any ideas? |
10-04-2013, 11:00 AM | #13 | |
Scooby Specialist
Member#: 321409
Join Date: May 2012
Chapter/Region:
SWIC
Location: Arrey, NM
Vehicle:2003 Big Effing Van 7.3L powerstroke diesel |
Quote:
Start another thread so we don't hijack the original poster. |
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10-04-2013, 11:17 AM | #14 |
Scooby Newbie
Member#: 329793
Join Date: Aug 2012
Location: South Point, Ohio
Vehicle:2002 WRX PSM |
Ok, just noticed that my pressure control valve is plugged into the wiring harness...but no lines are running to it, one of which is broken and taped over.
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10-04-2013, 04:49 PM | #15 |
NASIOC Vendor
Member#: 4803
Join Date: Mar 2001
Location: Austin, TX
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Do you have any logs? Have you tried working with your tuner to see if they have any input?
Is this something that started happening recently? Or has it been going on since the car got tuned? Has anything been changed on the car recently? The lean code is definitely concerning and will give you and idea as to what could be the problem. You may have a pre-turbo intake leak. Your front O2 could be worn/failed. Your MAF could be worn/failed. Your MAF scaling and/or injector scaling in your tune could need some work. Those are all just guesses though. - Chris |
10-04-2013, 04:58 PM | #16 |
Scooby Newbie
Member#: 329793
Join Date: Aug 2012
Location: South Point, Ohio
Vehicle:2002 WRX PSM |
Thanks Chris. Ive actually got 2 tuners on it, and plenty of logs. The system was leak tested from the short ram, before the maf, with no leaks. Scratching my head for a couple months now, as its a jdm swap in. Been running this way since before the tune, so its pre existing
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10-04-2013, 05:00 PM | #17 |
Scooby Newbie
Member#: 367325
Join Date: Sep 2013
Chapter/Region:
SCIC
Location: southern californa
Vehicle:2008 STi Hatchback White |
Among the mods listed I don't see an aftermarket fuel pressure regulator - Could the fuel pressure be fluctuating, causing the stutter?
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10-04-2013, 05:57 PM | #18 |
Scooby Newbie
Member#: 329793
Join Date: Aug 2012
Location: South Point, Ohio
Vehicle:2002 WRX PSM |
Thats correct, I dont have one- and its on my list of curiosities, but apparently there are a few potential issues here, im just trying to see if theres a way to pinpoint something specific so I dont try the buy everything approach lol
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10-04-2013, 06:30 PM | #19 |
Scooby Newbie
Member#: 367325
Join Date: Sep 2013
Chapter/Region:
SCIC
Location: southern californa
Vehicle:2008 STi Hatchback White |
I totally get that - it's easy to do the shotgun approach until the cash runs out
The way the FPR works is that it should be at a constant pressure until the manifold is under boost - then fuel pressure rises 1:1 - 1 psi manifold pressure => 1 psi fuel pressure increase. Hook up a fuel pressure gauge and see what's going on when it starts to flake out. If you see the pressure drop or fluctuate, you know you have a likely candidate (the other candidate for low fuel pressure is that the fuel pump is faulty, but Walbros are pretty reliable ...) |
10-04-2013, 07:45 PM | #20 |
Scooby Newbie
Member#: 329793
Join Date: Aug 2012
Location: South Point, Ohio
Vehicle:2002 WRX PSM |
Well I just noticed a code p0031 heater cintrol circuit low bank 1 sensor 1. That help out any?
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10-04-2013, 08:35 PM | #21 |
Scooby Specialist
Member#: 321409
Join Date: May 2012
Chapter/Region:
SWIC
Location: Arrey, NM
Vehicle:2003 Big Effing Van 7.3L powerstroke diesel |
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10-04-2013, 08:40 PM | #22 |
Scooby Newbie
Member#: 329793
Join Date: Aug 2012
Location: South Point, Ohio
Vehicle:2002 WRX PSM |
Welp I guess thats where ill continue spending lol. That seems to be a one problem issue, as I already checked the connectors and theyre fine.
I also started snooping around the bay and found that my ebcs wasnt completely hooked up correctly (didnt seem to affect performance), and my purge control solenoid valve was plugged in, but no lines were hooked to it at all (I hooked them up correctly). |
10-05-2013, 11:02 AM | #23 |
Scooby Newbie
Member#: 352498
Join Date: Apr 2013
Chapter/Region:
NESIC
Location: CT
Vehicle:2008 Wrx 2.5L World Rally Blue |
Check the plugs. I say this cause I had the same exact problem and my car was running super lean. I check the plugs and turns out I had a cracked plug.
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