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04-02-2023, 06:12 PM | #26 | |
Scooby Newbie
Member#: 467769
Join Date: May 2017
Chapter/Region:
NWIC
Location: Seattle
Vehicle:2018 STI Limited WRB |
Update: switched out the smoke machine heating element and got it to work - smoked both the intake track from the intake filter location and also smoked the exhaust since the machine was set up and didn't find any leaks at all. I'm not completely ruling out a leak as I was having some issues getting a good seal at the intake but there doesn't appear to be anything significant and enough pressure was built up to inflate a latex glove i was using to block off the intake.
Quote:
Car has only used Shell or Chevron 92 (best we can get in this area) from a newer station which used to be a Shell and then switched to Chevron a few years ago so Chevron is what the car has been using. Car has never thrown a code since I bought it but will see if there is anything pending - i know I've seen that with other cars that the system will note something isn't quite right but not off enough to actually trigger a code. Don't know if Subarus work that way though. Edit: checked for codes with the AP and none found. Also checked for pending codes using my Ultra Gauge which also returned nothing. Injectors are starting to look like the next possibility but wouldn't that likely cause other problems? Just seems weird that the car runs fine other than the idle drop off from a rev when no load is on the engine.
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Last edited by transmutation; 04-02-2023 at 10:23 PM. |
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04-02-2023, 11:41 PM | #27 |
Scooby Specialist
Member#: 510366
Join Date: Jan 2020
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I will say this: hope you are not chasing a ghost, you may never find it, I'm currently chasing a driveline gremlin lol.
But if it's definitely real then you just gotta go down the list. You have done the sinple stuff... Throw up a log if you have any, if not go get some logs! Edit: your getting in deep, may also help to throw up what you haveneliminated so far, like air filter etc. Also wouldn't hurt to call your tuner, sure he has heard this one before, just to get some ideas of where to go next... |
04-03-2023, 11:28 AM | #28 | |
Scooby Newbie
Member#: 467769
Join Date: May 2017
Chapter/Region:
NWIC
Location: Seattle
Vehicle:2018 STI Limited WRB |
Quote:
Good suggestion for logs - will try to get some this week which capture RPM, ST and LT trims. In summary I've tried the following: - Replaced Cobb filter with a new one - Cleaned MAF - Cleaned Throttle Body - Disconnected battery for 30 minutes and did idle relearn procedure - Smoked intake tract and exhaust and found no leaks - Replaced front and rear AFR and O2 sensors |
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04-07-2023, 07:47 AM | #29 | |
Scooby Newbie
Member#: 464145
Join Date: Mar 2017
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No boost leak
Quote:
Well, no boost leak, I ran out of things to check and I ran out of time before my tune. I called my tuner and explained to them what was going on. They said with all the bolts ons I have and going from the STI OEM injectors to 1050x that my car is NOT going to run right at all. I had to get it towed to the shop. It passed inspection and they tuned it on the dyno. It runs GREAT now! Sorry for hijacking your post. I just wanted to give an update. |
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04-07-2023, 01:15 PM | #30 |
Scooby Newbie
Member#: 467769
Join Date: May 2017
Chapter/Region:
NWIC
Location: Seattle
Vehicle:2018 STI Limited WRB |
Glad you got your problem figured out!
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04-07-2023, 01:42 PM | #31 |
Scooby Specialist
Member#: 283429
Join Date: May 2011
Chapter/Region:
South East
Location: Down yonder.
Vehicle:2016 Fuji Sunfire 03 Silver |
Forget all that vacuum/boost leak crap - negative fuel trims mean you have a rich condition - to much fuel. The ECM is reducing the fuel. Vacuum leaks would give positive trim - adding fuel due to too much air.
Since you have swapped the A/F sensor next thing I would look at is what the ECM sees for coolant temperature. an open wire, open sensor, or incorrect reading (too cold) would cause a rich condition. One big clue would be extreme fuel smell in exhaust and possible black smoke. |
04-07-2023, 01:55 PM | #32 | |
Scooby Newbie
Member#: 467769
Join Date: May 2017
Chapter/Region:
NWIC
Location: Seattle
Vehicle:2018 STI Limited WRB |
Quote:
Thanks for your input. The car does smell rich but no smoke (of any color) is visible. Dumb question - how can i see what the ECU is seeing for temps? Is that the same as what would be reported by the AP? I haven't noticed anything odd as far as temps and the car does get warm enough to kick on the fans but sounds like possibly there is more to consider here? Last edited by transmutation; 04-07-2023 at 02:03 PM. |
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04-10-2023, 05:40 PM | #33 | |
Scooby Specialist
Member#: 510366
Join Date: Jan 2020
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04-15-2023, 05:33 PM | #34 | |
Scooby Newbie
Member#: 467769
Join Date: May 2017
Chapter/Region:
NWIC
Location: Seattle
Vehicle:2018 STI Limited WRB |
Quote:
Thanks! Took the car out today and verified that coolant temp and intake temps seem to be reading correctly (coolant was between 180-185 for most part and intake between 59-73 with ambient of mid 50s). I have an STI so no oil temp gauge unfortunately. I have an appointment with my shop this next week so hopefully they can figure out what is going on. |
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04-15-2023, 05:36 PM | #35 | |
Scooby Specialist
Member#: 510366
Join Date: Jan 2020
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Quote:
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04-28-2023, 05:55 PM | #36 |
Scooby Newbie
Member#: 467769
Join Date: May 2017
Chapter/Region:
NWIC
Location: Seattle
Vehicle:2018 STI Limited WRB |
Update but not really update:
Car went back to the tuner shop that installed some of the mods and did the dyno tune. They redid all the same intake tests that i did and eventually found a small leak on the driver side intake manifold. Replaced the gaskets and said all was well. Picked the car back up today and no real change - might be slightly better but definitely still not solved. Car almost dies when revs drop with no load on the engine. Thinking next steps now are pulling the spark plugs (as i will be there) and injectors and see if i can find a place to clean and test the injectors. Open to any recommendations for that if someone has had a good experience with cleaning and flow testing. Also, is there a way to test the fuel pressure regulator just to rule that out? Last edited by transmutation; 04-28-2023 at 06:31 PM. |
04-28-2023, 05:55 PM | #37 |
Scooby Newbie
Member#: 467769
Join Date: May 2017
Chapter/Region:
NWIC
Location: Seattle
Vehicle:2018 STI Limited WRB |
Double post, double no real update.
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04-28-2023, 08:21 PM | #38 |
Scooby Specialist
Member#: 510366
Join Date: Jan 2020
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Dont got much man, but sounds like a crappy tuner shop if they cant rule out spark and fueling. I mean its a 2018, so shouldnt even be an issue.
Did you get any logs? |
05-20-2023, 09:59 PM | #39 |
Scooby Guru
Member#: 108051
Join Date: Feb 2006
Chapter/Region:
AKIC
Location: Oneonta, NY
Vehicle:2005 WRX STi WRB |
What's fuel pressure when it acts up? Maybe an injector is hanging open? That's my bet... Was it doing this before or during the first tune? Or did it randomly start doing that recently?
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06-02-2023, 10:46 AM | #40 | |
Scooby Newbie
Member#: 467769
Join Date: May 2017
Chapter/Region:
NWIC
Location: Seattle
Vehicle:2018 STI Limited WRB |
Quote:
Yeah not gonna lie pretty disappointing. Haven't pulled logs yet as other life things have been busy but will do some research on the whole Green Speed thing (my AP hasn't been plugged into a computer in several years) and look into that. Just trying to be careful as I'm running the older flex fuel system which Cobb discontinued. What data points would be good to pull? Last edited by transmutation; 06-02-2023 at 11:14 AM. |
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06-02-2023, 10:54 AM | #41 | |
Scooby Newbie
Member#: 467769
Join Date: May 2017
Chapter/Region:
NWIC
Location: Seattle
Vehicle:2018 STI Limited WRB |
Quote:
Fuel pressure sits between 34-35 or so measuring final pressure on the AP while the car is bogging. Raw pressure seemed to be about the same. Seems to stay at the same pressure when the idle settles out also. Issue was not present when car was stock or for maybe 1.5 years after mods and tune and just started earlier this year. At this point I'm also wondering if something is going on with an injector as i believe i have ruled out a vacuum/boost leak, replaced both O2 sensors, cleaned MAF and TB, and also put in a new air filter. Once the car corrects itself it does idle fine and otherwise runs and accelerates great. |
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06-19-2023, 06:46 PM | #42 | |
Scooby Newbie
Member#: 534640
Join Date: Jun 2023
Location: PA, WA
Vehicle:2011 Wrx Hatch |
Quote:
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06-20-2023, 03:55 PM | #43 |
Scooby Newbie
Member#: 467769
Join Date: May 2017
Chapter/Region:
NWIC
Location: Seattle
Vehicle:2018 STI Limited WRB |
I'm no export but what you are describing does sound at least partially like symptoms of a failing O2/AFR sensor. The video I linked earlier in the thread has some details about that - the poster ended up unplugging his primary O2 to test it before springing for a new one.
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06-21-2023, 09:16 PM | #44 |
Scooby Newbie
Member#: 389352
Join Date: Apr 2014
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Just ran into the same exact problem a week ago... turns out it was a bad head gasket and a cyl 3 misfire, which was pushing coolant high up into the reservoir, which caused the factory radiator hose on top to rupture a few weeks prior... take it to a reliable mechanic and have him take the motor apart, then you'll know for sure.
-- 2014 wrx hatch Pro-tuned @GST Motorsports cobb sf intake tgv deletes gfb pulley kit |
06-21-2023, 09:29 PM | #45 |
Scooby Newbie
Member#: 389352
Join Date: Apr 2014
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Also, replace your timing belt gears, they are worn. Do the entire service. #trust
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07-06-2023, 11:12 AM | #46 |
Scooby Newbie
Member#: 467769
Join Date: May 2017
Chapter/Region:
NWIC
Location: Seattle
Vehicle:2018 STI Limited WRB |
OP checking back in here. Still trying to figure out what is going on. Since last update I've done a compression test which check out fine (spark plugs looked good also) and also replaced the MAF just to rule that out. No change in the bogging behavior.
I will do my best to update this thread if i can figure out what the problem is. |
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