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07-24-2013, 07:59 PM | #1 |
Scooby Newbie
Member#: 301247
Join Date: Nov 2011
Location: Toronto
Vehicle:09 Impreza 2.5i MT White |
please help, engine knocks bad at ~2500rpm
Hi guys I have a 2009 impreza 2.5i auto with only 40k miles on it. I do all the service and maintenance regularly including Spark plugs (ngk laser platinum). Anyway according to my logs engine knocks bad between 2000-3000rpm under heavy load (full throttle). So much so that IAM drops to zero and engine pulls as much timing as possible which often leads to poor low end power (more like non existent power). BUT I don't hear any knocks or pings. Once I had bad gas in there and I heard some pinging but after that no more. Even still my car pulls timing and reports knocks. my car does have a noisy heatshield/exhaust at low RPMs in hot weather. Am I a victim of false knock? I use premium gas only and car is stock.
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Last edited by Pickler; 07-25-2013 at 11:22 PM. |
07-25-2013, 11:18 PM | #2 |
Scooby Newbie
Member#: 301247
Join Date: Nov 2011
Location: Toronto
Vehicle:09 Impreza 2.5i MT White |
bump...
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07-26-2013, 02:58 AM | #3 |
Scooby Guru
Member#: 124254
Join Date: Aug 2006
Chapter/Region:
NESIC
Location: Rhode Island
Vehicle:2006 06 SGM Slowbaru "The Scoobinator" |
You're still under warranty, so I'm going to say take it to a dealer.
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07-26-2013, 07:11 AM | #4 |
Scooby Newbie
Member#: 301247
Join Date: Nov 2011
Location: Toronto
Vehicle:09 Impreza 2.5i MT White |
will the dealership accept data logs? how am I going to prove knocking if its not audible?
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07-26-2013, 08:39 AM | #5 |
Scooby Guru
Member#: 120
Join Date: Jul 1999
Chapter/Region:
AKIC
Location: Where the Navy sends me...
Vehicle:1997 Legacy 2.5GT 1996 Impreza coupe |
Tell them you can feel the car hesitating, like it's pulling timing around 2500rpm.
Have you datalogged any other, similar cars to see how they behave? |
07-26-2013, 08:58 AM | #6 |
Scooby Newbie
Member#: 301247
Join Date: Nov 2011
Location: Toronto
Vehicle:09 Impreza 2.5i MT White |
yes but that was an acura. it had no issues with knocks despite 15 psi of boost and it built timing slowly but gradually up to redline (no dips or spikes in timing). this car I have been feeling hesitations at 2500 rpm for years. just didnt know what was wrong with it until I got a tactrix cable, and notice knock retards at those exact engine speeds. Dealership always claims the car is fine. This morning on the drive to work while climbing a small hill at 2500rpm timing dropped to 0 degrees. This was with a rich AFR mixture too.
Last edited by Pickler; 07-26-2013 at 09:05 AM. |
07-26-2013, 09:34 AM | #7 |
Scooby Guru
Member#: 120
Join Date: Jul 1999
Chapter/Region:
AKIC
Location: Where the Navy sends me...
Vehicle:1997 Legacy 2.5GT 1996 Impreza coupe |
I think you missed the bit about "similar" - an Acura with an aftermarket turbo setup is not similar to your N/A 2.5i.
So, let me be more specific - have you datalogged another N/A Subaru? |
07-26-2013, 09:45 AM | #8 |
Scooby Newbie
Member#: 301247
Join Date: Nov 2011
Location: Toronto
Vehicle:09 Impreza 2.5i MT White |
oh sorry but thats why i said 'but' it was an acura lol. and it was factory turbo just over boosted (rdx). I have never seen logs of other NA subarus. seen plenty of turbo subaru logs though. I actually would love to see a log of na subarus on pump gas doing some pulls.
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07-26-2013, 09:49 AM | #9 |
Scooby Newbie
Member#: 342299
Join Date: Jan 2013
Chapter/Region:
SWIC
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They can read the ECU and see that the IAM has dropped and any learned knock correction values. They won't need your datalogs if it has been knocking that much.
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07-27-2013, 11:24 AM | #10 |
Scooby Newbie
Member#: 301247
Join Date: Nov 2011
Location: Toronto
Vehicle:09 Impreza 2.5i MT White |
well I just took it to dealer and they dont know what im talking about when I mentioned the IAM.
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07-27-2013, 12:43 PM | #11 |
Scooby Newbie
Member#: 342299
Join Date: Jan 2013
Chapter/Region:
SWIC
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07-27-2013, 01:54 PM | #12 |
Scooby Newbie
Member#: 301247
Join Date: Nov 2011
Location: Toronto
Vehicle:09 Impreza 2.5i MT White |
that's what i'm doing, i'm looking for a new dealership but there are not much around here. They took my car for a drive and came back saying no knock was present. Went home, hooked up my data logger and instantly read that IAM was at 0.
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08-01-2013, 04:14 PM | #13 |
Scooby Newbie
Member#: 361609
Join Date: Jul 2013
Chapter/Region:
E. Canada
Location: Richmond Hill, ON, Canada
Vehicle:2015 WRX CVT WRB Pearl |
Not to worry I am in the same boat, and you can use my car by testing it out with the data logger.
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08-01-2013, 11:41 PM | #14 |
Scooby Newbie
Member#: 301247
Join Date: Nov 2011
Location: Toronto
Vehicle:09 Impreza 2.5i MT White |
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08-02-2013, 05:18 PM | #15 |
Scooby Newbie
Member#: 197937
Join Date: Dec 2008
Chapter/Region:
E. Canada
Location: Montreal, QC
Vehicle:2016 Golf R Under the radar silver |
As i've mentioned in other threads, i'm a big advocate of running higher octane gas (at least in my car - 09 2.5i 4EAT), running 89 or 91 (even when it was stock) certainly smoothed out the lumpy feeling it had at low revs under high load (e.g uphill in top gear). I wasn't logging the car back then so I can't comment whether it was pulling timing or not.
Even if you are stock, I definitely recommend getting a tune. |
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