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Old 01-16-2013, 10:22 AM   #1
I WANT AN STI
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Aspen White

Default making less power with built motor/ not really sure where else to put this.

Hello, I am having a little dilemma here. I just bought a highly modded 05 sti and I wasn't really sure where to put this but this seemed like the most appropriate place.

current mod list as follows.

399HP and 357TQ @ 22.5 psi
- Engine built and tuned by Agile Automotive
- APS SR55 ball bearing turbo
- Mahle forged pistons
- Forged rods
- Cosworth Cams Intake 278 / Exhaust 274
- Cosworth valve springs and retainers
- Cosworth high pressure oil pump
- ACL high performance main bearing
- ACL high performance rod bearings
- XX Tuning fuel rails
- DeatschWerks 850cc side feed injectors
- KS Tech Mega MAF Type 1 73mm short ram intake
- AEM dry flow filter
- Samco turbo inlet hose
- Hyperflow FMIC
- Hyperflow catch can
- Vibrant FMIC piping couplers
- Turbosmart BOV
- Walbro 255
- Hyperflow oil catch can
- Koyo radiator
- Invidia up-pipe
- Agency Power unequal length header thermal coated with EGT tap
- Gimmick Motorsports V3 v-band catback thermal coated
- Invidia V2 bellmouth catless downpipe



Needless to say the car is super fun to drive, however........

It is so bad on gas that I can only drive it like once a week. I may need to sell the car anyhow sadly. But if I am able to keep it I would like to actually drive the car everyday so that I can sell my other daily driver, get a little money back and only have to pay for 1 insurance policy.

My question to you all is....Will having that larger turbo along with a built motor compromise the cars integrity and reliability if I put the stock sti top mount intercooler on it, replaced the 850's with stock oem injectors and had the car retuned to more of stock or maybe stage 2 power ? Im not quite certain if having that larger turbo will cause a problem or if I need to sell it and replace it with a stock one to go along with the other stock components I am wanting to put back on.

My last sti was making like 270 on stock injectors, top mount and turbo with a base tune and I was perfectly content with the power and the fuel mileage being mostly affordable to drive it everyday. This current setup gets about 9-11 miles to the gallo around the city and will literally cost me 120 dollars a week in fuel. Thats just not going to work. it doesnt do too bad on the highway but I am never really on the highway.

anyhow, thank you for any input and info.

Rick

Last edited by I WANT AN STI; 01-16-2013 at 10:35 AM.
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Old 01-16-2013, 10:28 AM   #2
SubieLuvin
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Have you considered just getting it retuned? Bring it to your tuner with the goal of getting a more conservative "economy" map. Then get a tactrix cable and you could flash back and forth between the two maps so you can have the best of both worlds. Swapping the intercooler wouldn't really do anything for fuel economy, and 850 cc Injectors really arnt very big anyway.

Edit I hope you mean 9-11 miles to the gallon not tank. If you are only getting 11 miles per tank you probably have a hole in your gas tank.
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Old 01-16-2013, 10:41 AM   #3
I WANT AN STI
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yea sorry, edited that. mpg

I have thought about retuning it but it seems to be a really good tune, just by nature being a gas hog. My wideband and the tuning map show excellent a/f ratios in and out of boost. and yea I wasnt thinking the stock i/c would do anything for gas mileage but it would be more of a stock setup. But it would probably be more beneficial to keep the front mount I assume since it would be cooling quite a bit more and the turbo certainly doesn' t need to spool any faster than it already does ha.

I have had 2 wrx's and 1 other sti, none with anything bigger than the stock 05 sti injectors so 850's and a larger fuel pump was just something that stuck out to me and figured would be smartest thing to replace back to stock to get a little better mpg.

I wasn't planning on driving this car everyday, it was just going to be a weekender. But getting into my 91 civic everyday and then driving the sti on nice days makes me wonder how long Ill be able to put up with getting into the civic instead of the sti for my daily commute. ha. The sti is just so nice and comfy inside, not to mention nearly 20 years newer .
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Old 01-16-2013, 10:42 AM   #4
kakarot09
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Even at 9-11 miles per gallon that's terrible. I get around 9 at the track. Maybe you have a leak somewhere. Also could be something funky with injectors or tune but I doubt it's the tune based on his reputation.
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Old 01-16-2013, 10:48 AM   #5
I WANT AN STI
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Agreed, its absolutely terrible gas mileage even for a car making that kind of power. I was getting nearly double that with my last sti and a little better with my upgraded wrx. I have checked for leaks but have found nothing. and yea the tune seems solid and like I mentioned the air/fuel looks good when im driving on the aem wideband. Might need to maybe take a trip somewhere and get the tune looked at. only problem is nobody around my area tunes on the accessport. closest place is about 2.5 hours away and that alone will cost me over a hundred dollars just to get there.
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Old 01-16-2013, 10:54 AM   #6
kakarot09
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What are afrs when you're driving around?
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Old 01-16-2013, 10:56 AM   #7
SubieLuvin
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There are vendors here that would probably give you advice towards your map if you sent them a data log. Or if you posted one in the tuning section some people may have some input. Like previously mentioned though the tuner has a great reputation around here. But if there is a mechanical fault causing it a data log may help give you an idea of what it could be.
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Old 01-16-2013, 11:12 AM   #8
FuJi K
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You might have a dying front o2 sensor. Look over everything to make sure you have no leaks and such. Always make sure any and every mechanical part is working properly first. This is the health of the engine. The tune doesn't change once set. If there was a hose that blew off the fuel pressure regulator and your engine blew when you did a WOT pull, you can't suspect the tune was bad.
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Old 01-16-2013, 11:18 AM   #9
I WANT AN STI
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Car is beetween 11.5 to 12.5 in full boost depending on rpm and gear. Cruising at minimum throttle is in the 16.5 to 17.0 range.

Of course the wideband may be off or not reading correctly. Car doesnt overly smell of fuel anytime neither.

I will spend some more time looking tomorrow or later this afternoon when the weather clears up.
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Old 01-16-2013, 12:47 PM   #10
kellygnsd
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Quote:
Originally Posted by I WANT AN STI View Post
Car is beetween 11.5 to 12.5 in full boost depending on rpm and gear. Cruising at minimum throttle is in the 16.5 to 17.0 range.

Of course the wideband may be off or not reading correctly. Car doesnt overly smell of fuel anytime neither.

I will spend some more time looking tomorrow or later this afternoon when the weather clears up.
What wideband do you have and when was the last time you did a free air calibration if needed?
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Old 01-16-2013, 12:02 PM   #11
kakarot09
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That all sounds too lean. Full boost afr of 12.5? afr for cruise at 17? Sounds like you need to check both the stock O2 sensor and your wideband. More likely that the stock O2 sensor is bad like Fuji said.
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Old 01-16-2013, 12:30 PM   #12
I WANT AN STI
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Is there anyway of recalibrating a wideband or no ? Car has no cel's so I have not though of a bad front 02 sensor.

11.5. To 12.5 during fullboost/partial boost. And yes the gauge will hit 17 sometimes when im just barely holding the throttle at 60mph.

For the first week i only boosted on the car 1 time and I got 146 miles to my tank. I drove to work and back twice and had to fill up. I work 26 miles from home and ran an errand or two than put the car in the garage and have only driven it once to the store cause Ill empty my bank account driving this car too often. I can seemingly literally watch the fuel gauge move towards E.

Sidenote that might be related : It takes me 10 minutes to fill my tank up..pump will stop after .02 gallons and will not pump continuously. Assuming its probably a charcoal cannister problem from what ive researched but have not yet tore it apart to see if its all deteriorated orr clogged yet. Thats on the agenda for this week. I am not sure if that would effect mpg or not.
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Old 01-16-2013, 01:00 PM   #13
kakarot09
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He said it was aem. No free air calibration.
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Old 01-16-2013, 06:40 PM   #14
Slimsti
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Ur afr's are horrible and either the sensor is bad or the tune is bad. Also if u have a tactrix download learning view and post up ur results. Your a,b,c,d afr learning should all be -8/+8. When my front o2 was bad I was getting 13mpg and my a and b bank was 22% and 19%.
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Old 01-16-2013, 09:10 PM   #15
marios03wrx
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that is 05 WrX Power'd

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Didnt the 05 & up wrx/sti have some ties to rear o2 sensor that affects fuel mileage? It wouldn't hurt to check if there is a CEL fix installed in the wiring & if there is a spark plug non-fouler installed.

Mario
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Old 01-16-2013, 09:37 PM   #16
danger1138
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Quote:
Originally Posted by marios03wrx View Post
Didnt the 05 & up wrx/sti have some ties to rear o2 sensor that affects fuel mileage? It wouldn't hurt to check if there is a CEL fix installed in the wiring & if there is a spark plug non-fouler installed.

Mario
I have a spark plug non fouler for my rear o2, maybe i should take it off? Im also getting poor gas mileage, all be it not ad bad as op but close.
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Old 01-16-2013, 09:43 PM   #17
marios03wrx
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that is 05 WrX Power'd

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Quote:
Originally Posted by danger1138 View Post
I have a spark plug non fouler for my rear o2, maybe i should take it off? Im also getting poor gas mileage, all be it not ad bad as op but close.
Let me see if i can find the thread, but im pretty sure it is only an 05+ problem.

Mario
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Old 01-16-2013, 10:19 PM   #18
k mier
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Quote:
Originally Posted by marios03wrx View Post
Didnt the 05 & up wrx/sti have some ties to rear o2 sensor that affects fuel mileage? It wouldn't hurt to check if there is a CEL fix installed in the wiring & if there is a spark plug non-fouler installed.

Mario
IIRC, the rear O2 only affected fine adjustment of long term fueling.

I don't know where all that fuel is going but I'll average 16mpg's w/e85 making +20hp more. Something is definitely wrong.
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Old 01-16-2013, 09:48 PM   #19
danger1138
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That was one of the first mods i did after the Turbo back exhaust.. I forgot why i did it, something to do with the CAT efficiency threshold.. Help me out. I also did this mod on my RS after installing an exhaust.
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Old 01-16-2013, 10:12 PM   #20
marios03wrx
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Quote:
Originally Posted by danger1138 View Post
That was one of the first mods i did after the Turbo back exhaust.. I forgot why i did it, something to do with the CAT efficiency threshold.. Help me out. I also did this mod on my RS after installing an exhaust.

Here is the thead..
http://forums.nasioc.com/forums/show....php?t=2234058
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Old 01-17-2013, 03:21 PM   #21
I WANT AN STI
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well its been really nasty weather here lately, once it clears up im gonna get under the car and check for the cel fix on the 02 and then do a real good check for leaks. Thank for all the suggestions and such guys.

hopefully its just a bad 02 sensor that I can replace and start getting at least 18-20 mpg. that would be real nice
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Old 01-17-2013, 10:09 PM   #22
spoolinsti05
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let us know how you make out. Deff don't want any o2 fix i went threw that.
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Old 01-18-2013, 02:57 PM   #23
I WANT AN STI
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Was able to get under the car for a bit today. Looked all over and didnt find any leaks. Saw no evidence of a cel fix either.

I did however take my charcoal cannister off and all the charcoal poured out like a waterfall. Im assuming thats no supposed to happen ?
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Old 01-20-2013, 07:55 AM   #24
I WANT AN STI
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Well the fueling up issue is now fixed, I was able to fill my tank until the pump shut off. I will be driving it this week to recheck the fuel mileage now that its legitally filled.

Can anyone tell me what my idle air fuel ratios should be ?
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Old 01-20-2013, 10:56 AM   #25
kellygnsd
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AFRs should be around 14.7:1 at idle.
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