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Old 12-09-2017, 02:31 PM   #1
d0rkiishchris
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Default 2017 Subaru Impreza 20k miles pinging

Wondering if anyone else has heard pinging or detonation on these 2.0i NA engines? When I'm in fourth hard accelerating hard I'm getting slight pinging. This car being so new, I'm worried about if it needs a computer update.

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Last edited by d0rkiishchris; 12-09-2017 at 02:56 PM. Reason: Spelling
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Old 12-09-2017, 09:01 PM   #2
d0rkiishchris
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anyways, I've researched the actual motor (FB20D) which has a pretty high compression ratio of 12.5:1. I've never owned a car that had such compression that was able to run on 87 octane (AKI or (R+M)/2) or 91.1 RON). I've had cars with less compression that required 91 or even 93 octane.

I didn't notice it happening until about 12,000 miles. Figured it was a relay or cam-phaiser noise. But it consistently happened in 3rd or 4th under load. Not lugging, but not in the best RPM range. So I thought maybe I was lugging it too much and changed my driving habit and did the best I could to run out the carbon build-up. That didn't change anything, if anything it became more frequent. Generally getting up to speed and accelerating through 4th.

So, I read the manual. The manual says occasional knocking or pinging is ok, just not throughout the entire rpm range and all the time. This didn't sit well with me, but yeah the manual literally says that (not verbatim). I believe the page is 7-3. Any pinging over the life of a car is going to put pits into the piston head over time. Maybe not until 120,000 miles, but still, why let it happen. So they've made the motor smaller for these new imprezas but maintained hp with variable cams, direct injection, and pretty high compression. Higher than a Honda S2000, which in the US was 11.1:1, and even that requires 91 octane (AKI) or higher.

So Subaru must be implementing some fast reacting computer anti-knock system to sell the cars saying 87 octane is ok. And it is pretty fast, it might ping once or twice under a strong pull out of first between 5 and 6k rpm, but it stops it and if you do a strong pull right after it won't ping at all, most of the time. I reset my computer today to see if maybe if needed to learn some new fuel mapping, but that helped nothing. Full throttle in first, pinging begins between 5k and 6k rpm almost every time. This computer must be massively retarding and advancing the timing. So much so that a knock here and there will be unavoidable on 87.

So tonight I decided to put in what I would think would be a good octane for 12.5:1, 93 octane. Its not faster. Its not going to be. Felt like it was running better, but that is just a placebo. But the car no longer pinged. At all. Ever. 4th gear 3000 rpm normal acceleration which it always pinged, gone. 1st gear hard between 5k and 6k, gone. I don't want to run gas that is $.60 more a gallon, so I'm going to try 89 octane next. But this engine isn't really a "regular gasoline" (87 octane AKI) engine.

Or, maybe my cars anti-knock system is slow and defective. Just was curious what other owners have noticed. CVT guys probably won't get a knock or ping ever since you're always in that optimum rpm.
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Old 12-12-2017, 12:56 PM   #3
GEE-OTTO
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Without some type of monitor device/software you cant really be sure of the detonation events in frequency or origin. If they have something for your model I would obtain it and start monitoring, it's great to see what your car is doing or why it's doing it

Keep in mind retarding timing to mitigate knock isn't a bad strategy for those wanting an engine to "work" 87 is popular selling point and to the majority of 2.0L based Subaru owners they wont pick up on or even know what "pinging" "knock" "detonation" are.

EZ30 suffered a similar fate
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Old 12-26-2017, 11:21 AM   #4
Elbert Bass
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Currently there is no reflash for pinging for a 2017 DINA engine. The direct injection system allows the use of regular grade fuel with higher compression. Unfortunately there are fuel suppliers that sell "questionable" fuels which may be the issue. Try buying from a different brand/station and if that doesn't resolve it step up your octane, although Subaru tells us that is not necessary.

Last edited by Elbert Bass; 12-26-2017 at 11:36 AM.
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Old 12-26-2017, 12:00 PM   #5
d0rkiishchris
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I've tried many different stations. Last night I went to the local shell that I've never had a problem with in my previous vehicle. Today it's pinging , what I consider anyways, pretty bad. The average driver prob. wouldn't notice. So right now I just put in 4 gallons of 93 to balance it out. 89 seems to be ok. A random ping every now and again, but 89 is alright. Gas stations used to just charge $.10 more per gallon for every grade higher. Now, you never know what it's going to be. They charge 2.15 for 87 and 2.79 for 93aki octane. That's some bs.
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Old 04-21-2020, 05:44 PM   #6
4NDY1980
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Did you ever sort this?
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