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Old 03-22-2021, 07:25 PM   #1
stiowa2020
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Default 2020 STi Misfire P0302 Questions

Recently picked up a 2020 STi mileage is currently at about 9,000 miles and had about 5k on it when we got it, Certified Dealer car. Car is stock except for an Invidia Cat Back exhaust. Over the course of about 3 months I've gotten 3 separate P0302 Cylinder 2 misfire codes. Car doesn't seem to run or drive any different when it happens, not a noticeable misfire. All 3 have happened in the morning, going downhill my driveway with plenty of gas in the tank. The first time I sent the car to the dealer with the CEL still on and they said they found nothing wrong and cleared the code and it didn't come back. The next 2 times I read the code and cleared them after screen-shoting the scanner and drove to dealer. ( I like cruise control so I cleared them to use cruise) Dealer is saying there is nothing wrong with the car and says nothing they can do. I then started asking them simple questions pertaining to what causes misfires. Compression, fuel pressure etc...

They texted me the compression results 3 days after asking for the numbers and they gave me 1 – 120psi, 2 – 122psi, 3 – 120psi, and 4 – 130psi with a leak down test at 3-7% across the 4. Service manual calls for 142-171 on a warm motor. Dealer says they don't like to do warm compression tests so they do them cold. Manual also calls for no more than a 7psi difference between any cylinders. This motor from their numbers are 8-10psi difference. After i questioned them about it via email with the screenshots from the earlier messages they now claim that all 4 cylinders were at 120psi. ALL THE EXACT SAME????

Anyone else seeing misfire codes on newer STi's? This one is still under an 8 year bumper to bumper warranty or I would take it somewhere besides a dealer.
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Old 03-22-2021, 09:00 PM   #2
JP Chestnut
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You should be taking that car in every time it happens. It’s. PITA, but if something goes seriously wrong after the dealer tells you it’s nothing you’re going to want that paper trail.
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Old 03-22-2021, 09:50 PM   #3
ntg44
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2020 WRX STI

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Ask them to check for cylinder harshness or drop the oil pan. Believe it or not it can be a spun bearing.
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Old 03-22-2021, 10:07 PM   #4
stiowa2020
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My paper trail has already begun, i have all their texts as well as emails now. I had to ask them about compression, fuel pressure and plugs. I'm not a huge dummy but I also don't know the "specs" off the top of my head so I got the service manual so I could have the true numbers. the first time i took it in literally all they did was clear the code and i know this because i had asked the same questions then as now and they just said "o yeah it all checked fine" LOAD OF BS!! they didnt chek anything as noted in their service report. "Cleared code, it didnt come back" Its now a game to me to simply read out of the service manual the steps for troubleshooting the CEL code haha, they be stumped at each question. Took them 3 days to get back to me with the compression numbers and fuel pressure with and without vac to the regulator. They are getting adamant that I come get the car because there isnt anything wrong with it and bring it back again when the light comes back, simply told them i will come get it when they can tell me why a car certified by them has thrown a misfire code 3 times in under 3 months. I have a loaner from them so i guess less miles on the STI haha. Was just curious if anyone else has had similar problems on their new STI's.

@ntg44 i was going to go down the electrical route next conversation i have with them. they are supposedly cold starting it tomorrow and going to assess the car again. We shall see tomorrow.
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Old 03-22-2021, 11:46 PM   #5
JSR84
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Quote:
Originally Posted by ntg44 View Post
Ask them to check for cylinder harshness or drop the oil pan. Believe it or not it can be a spun bearing.
Yeah, if it's a spin bearing there would be accompanying indicators.
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Old 03-23-2021, 07:43 AM   #6
ntg44
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Quote:
Originally Posted by JSR84 View Post
Yeah, if it's a spin bearing there would be accompanying indicators.
Not for mine there wasn't. Wish I could elaborate further but unfortunately I had to sign a NDA. Just strongly suggesting OP to consider my suggestion because the situation sounds suspiciously familiar.
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