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Old 01-11-2020, 04:15 PM   #1
Scooby Newbie
Member#: 159744
Join Date: Sep 2007
Location: Cincinnati, OH
2004 STi

Default 04 sti sumbled then quit and wont restart

Hey guys I have an 04 sti, bought it a few months ago with 182k miles. Has some simple bolts-ons tbe, tmic, bov, intake, gauges but unsure on what the tune is if it has one at all. The car ran great but would usually stumble and hesitate in the mornings until it warmed up then ran perfectly fine after that. One morning though it stumbled pretty bad and just quit and wouldn't restart. No cel. Fuel pump is priming and and seems to be pumping a good amount of fuel at the rails. Haven't checked for spark or compression or anything else really. Just pushed it into my garage and got on here. My initial thought was maybe a cam or crank sensor went bad? Any help would be greatly appreciated.
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Old 01-11-2020, 05:54 PM   #2
Scooby Newbie
Member#: 49931
Join Date: Dec 2003
Chapter/Region: MWSOC
Location: Grand Rapids, MI
0305 wrx/Xt


Donít replace any sensors. Like you stated, check pressure at the rail(s). Inspect the plugs and coils and report back.
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Old 01-11-2020, 07:58 PM   #3
Scooby Specialist
Member#: 361325
Join Date: Jul 2013
Chapter/Region: E. Canada
Location: Ontario
2010 STi
Dark Gray Metallic


Do you have service records from the PO? If so, when was the timing belt last done?
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Old 01-12-2020, 11:28 PM   #4
NASIOC Supporter
Member#: 487
Join Date: Nov 1999
Chapter/Region: TXIC
Location: Greatwood/Sgrlnd
1998 /2005 STunIcorn
Acadia Green RS-T


Man would throw code if sensor

I agree with above post
Check FPress Check plugs
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Old 01-13-2020, 11:33 AM   #5
Scooby Specialist
Member#: 193940
Join Date: Nov 2008
Location: Philly
2004 WRX STI Black
RalliSpec Shortblock


Check the TB idle air controller. There is a small rubber gasket that over time cracks and causes to leak. Check it out first. In the link to the pic you can see where the controller and gasket are located. The link is for a WRX but i believe the 04 sti had the same or close to same TB. The WRX is a DBW but i believe the IAC is the same. If you decide to open and inspect the gasket, i would recommend replacing it with a new one even if the old one looks fine, because as soon as you release a 16 year old gasket, it will never seal the same.



Here is a link to a new gasket if you want to change it,


Last edited by BlackFighter; 01-13-2020 at 11:39 AM.
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Old 02-09-2020, 02:11 AM   #6
Scooby Newbie
Member#: 159744
Join Date: Sep 2007
Location: Cincinnati, OH
2004 STi


Alright guys, well I was finally able to find the time to mess with the sti. I put a fuel pressure gauge on it and and checked pressure, and with the key on it was about 38. I then tried to start it for the first time in about a month and it didn't start at first like before, and then the second try it actually started and ran. Not sure how it all of a sudden decided it wanted to start when the only thing I changed was installing the gauge. During the first cranking when it didn't start it was making an intermittent noise that almost sounded like a slight grind or vacuum leak. Made that noise 3 times during a 10 second crank. When it did start on the second try I noticed a slight miss while running. I believe it sounds fine other than that. Fuel pressure at high idle of 1300 was reading 45. I am thinking plugs and coils next to hopefully cure the miss. Or maybe could still be a weak pump or bad filter? Let me know what you guys think. I really appreciate all the help. I also have videos if that would help.
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