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Old 12-03-2019, 01:06 AM   #1
WolfPk
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Obsidian Black Pearl

Question all four cylinders misfire after fuel upgrade

upgraded my fuel system to flex fuel and just running the base map my tuner sent me for 91 before we go into e85, car will crank and run for 1-2 seconds very roughly, if i give it gas after starting i can keep it running and the gas is somewhat to pretty responsive but as soon as i try to idle it shuts down. i was giving it that gas to keep it running for a minute and engine light came on and showed up as all four cylinders misfiring, and and PFFFE code or something

AF correction and learn seem to be at 0 which seems off to me.

im thinking it maybe a problem with the tune or maybe even a vacuum leak? but this far ive checked everything and theres nothing that significant. ive had the entire tmic off and it would start and run.

if anyone has any ideas thatd be great
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Old 12-03-2019, 04:26 AM   #2
Zmanwrx23
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o2 sensor unplugged? ground wire/strap not attached correctly?
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Old 12-03-2019, 09:59 AM   #3
Valarius Starchaser
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What’s your fuel system pressure? Is it dropping after you cycle the key on?

It should hold pressure for several hours should be 43psi or somewhere there in if memory serves
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Old 12-03-2019, 12:53 PM   #4
WolfPk
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Rear o2 is not plugged in at the moment, I had to order a new wideband and I'm going to tap the old signal wire so it reads from. there.

Also I don't have the old sensor from
The secondary air pump delete but it's not throwing the code at the moment, i was thinking it could be changing the timing from limp mode, but it was running fine before. but maybe with the new tune it's throwing it off that much.
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Old 12-03-2019, 12:54 PM   #5
WolfPk
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Could you possibly send a picture of how your ground wire strap is connected? I removed mine and just put it on the chassis where the ebcs bolts on and the other end on the top of my intake manifold??? Could this be my issue???
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Old 12-03-2019, 02:48 PM   #6
kopele
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What fuel components did you change? Are AF correction and learning 0 in closed loop? Do you have a fuel pressure sensor? Log?
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Old 12-03-2019, 09:24 PM   #7
subaru_gc8
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Quote:
Originally Posted by WolfPk View Post
upgraded my fuel system to flex fuel and just running the base map my tuner sent me for 91 before we go into e85, car will crank and run for 1-2 seconds very roughly, if i give it gas after starting i can keep it running and the gas is somewhat to pretty responsive but as soon as i try to idle it shuts down. i was giving it that gas to keep it running for a minute and engine light came on and showed up as all four cylinders misfiring, and and PFFFE code or something

AF correction and learn seem to be at 0 which seems off to me.

im thinking it maybe a problem with the tune or maybe even a vacuum leak? but this far ive checked everything and theres nothing that significant. ive had the entire tmic off and it would start and run.

if anyone has any ideas thatd be great
maybe your scaling is off, what injectors did you have and what did you move to?
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Old 12-04-2019, 02:48 AM   #8
WolfPk
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hey guys i figured out the issue, somehow the turbo inlet was damaged and there was a significant vacuum leak. i wasn't aware that vacuum leaks could lead to misfires, but this seems like it was my issue, i wasn't able to tell until i got it to idle long enough that i could go under the hood and listen, heard a lot of air running in a spot it shouldn't have been so i sprayed some carb cleaner and the idle changed consistently.
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Old 12-05-2019, 02:14 AM   #9
AliBenn
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Your the man for posting the found issue!!
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Old 12-05-2019, 02:36 PM   #10
ThinWRX
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Quote:
Originally Posted by WolfPk View Post
hey guys i figured out the issue, somehow the turbo inlet was damaged and there was a significant vacuum leak. i wasn't aware that vacuum leaks could lead to misfires, but this seems like it was my issue, i wasn't able to tell until i got it to idle long enough that i could go under the hood and listen, heard a lot of air running in a spot it shouldn't have been so i sprayed some carb cleaner and the idle changed consistently.
I had that happen when I swapped to a vf52. I was doing a quick pull and heard a pop then a check engine light popped up. I limped the car home and knew it was going to be a torn inlet.
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