2007 Outback Ping

[kkingcqe]

My 2007 Outback with 236,000 miles pings.  It pings a lot.  Anything off idle it makes pinging noise.  Cannot hear it with windows up.  Tried Seafoam SS14 three times, Sunoco 94, octane booster.  First bottle of Seafoam seemed to help but three days later it was back.  New knock sensor.  New timing belt.

[1 Lucky Texan]

may need to scan the ecu for freezeframe data or better, live data. If you have a smartphone, an elm327 bluetooth adapter and an app can do that.

 

I suppose slipped timing might lead to pinging so, confirm cam timing.

 

was the old knock sensor cracked or decrepit in any way? what was the source for the present sensor?

[kkingcqe]

The timing belt was replaced last weekend with no effect.  Old knock sensor did not appear damaged in any way.  It was the first thing I thought of and replaced perhaps a year ago.  Do not remember where I got it but it made no difference.

 

I had a bad oil leak and was advised it was probably a head gasket.  Asked to have the carbon cleaned at time of replacement.  Turned out to be a failed valve cover gasket and since he could not get in touch with me he did not replace the gaskets.  He did do the timing belt, hoses, idlers, and thermostat.  I do have an endoscope but have not used it yet.  Planned on pulling a plug or two to have a looksee inside.

 

Car gets better than expected gas mileage. My commute is 50 miles each way over mostly country roads and it typically averages 28 MPG.  EPA highway is 27.

 

Thanks for the response!

[kkingcqe]

That ELM bluetooth adapter is downright cheap.  I'm assuming that unlike my stand alone code reader it will be able to provide real-time data and not just read codes.  I'll order one.  Do you recommend a particular app? What would I be looking for when I get into the data?

 

Just had a thought.  I only notice the pinging off-idle.  It could still be pinging when running harder but engine noise drowns it out.  Could this be an EGR valve issue?  Replaced that once and I have cleaned carbon out occasionally.  Still have the old one all cleaned up and I think I'll just go downstairs and swap them out now.

Edited October 20, 2017 by kkingcqe

[Gloyale]

carbon build up on piston tops.

 

Carbon heats up to nearly cherry red, sparks fuel mixture before it should.

 

Run lot's of good fuel treatment like lucas.  Seriously buy a 32 oz bottle and put 4~6 oz in the next 6-8 tanks.

 

If you really want to solve it.  Pull the heads and pistons, clean them, and replace rings and reseal engine.

[kkingcqe]

Carbon buildup is what I have been proceeding with.  Seafoam makes one of the most recommended products for this issue, SS-14.  It sprays directly into the air intake stream.  First time I used it I did not hear the ping for two days.  Then it came back.  Next two treatments did nothing.  I'm wondering if I just heard what I wanted to hear with the first can.  Had it in a garage last weekend for a couple of issues and they were supposed to pull the heads but some missed communication and it didn't get done.

 

I'm wondering if, since the ping is not evident when the engine is working hard, just at off-idle, that the carbon is not the correct issue to address.  I took a look at the EGR valve and the engine passages supplying it.  Found a lot of greasy black buildup in the passages.  Scraped out as much as I could then used carb cleaner to hopefully rinse out the rest.  I'm also going to scope a cylinder or two tomorrow to see just how much buildup is there. 

 

Thanks for your help Gloyale.  I've solved a few problems on this car using brainstorming just like this.  No one person had the correct answer but when I considered all of the suggestions the correct answer became apparent.  Cheers!

[GeneralDisorder]

The ONLY way to solve it is to replace the rings. The oil getting by them is causing the buildup, and the oil vapor reduces the effective octane of the intake charge as well. 

 

Re-ring is in order. All other measures will be VERY temporary and pretty much a waste of time.

 

GD

[Fairtax4me]

If there's heavy carbon buildup on the pistons, Next step is burned valves.

[kkingcqe]

Scoped cylinders almost no carbon. Oil burning is about 2000 miles to a quart.

[1 Lucky Texan]

plugs correct heat range for the car?

 

does the pinging get better if you run high octane fuel?

[kkingcqe]

Put in factory spec NGKs last change. Sunoco 93 has no effect. Might be worth changing the plugs.

[1 Lucky Texan]

seems like higher octane should reduce pinging.

 

maybe you could record the sound and post a link to it?

[GeneralDisorder]

It takes less carbon than you think. Last one I did had surprisingly little carbon also. There's a few years that seem to be sensitive to it. Around the 05 to 07 years Subaru had a lot of issues running stuff very lean. Rings and decarbon fixed it. Oil consumption should be about half a quart or less in 3k. 

 

GD

[kkingcqe]

I'm wondering the source of the oil consumption figure since Subaru of America has been saying that ~1000 miles to a quart is okay even for a new engine. My question for GD is have you seen this same problem and can directly attribute it to the carbon and rings? My car runs great and if you never put the windows down you would never know there was a problem. 

 

The ping or clatter is not under heavy load.  It is with minimal throttle pressure and load, like when I am driving to attain maximum fuel economy. Subaru repair manual does not acknowledge this as a condition that can happen.

 

I appreciate the passion and certainty that several folks have related in their postings.  But I have owned Subarus for almost 20 years and have literally spent thousands of dollars fixing things that weren't bad.  Would seem reasonable to offer anyone who is sure of their solution to this problem that I'll pay twice if your solution actually fixes the problem.  You pay for the fix if it doesn't.  Made that same offer to the Subaru dealer in Lansing, MI about 15 years ago on the check engine light of my '96 and he would not take the bet.

 

I don't think I will be able to record the sound.  My smart phone does not deal with sound very well and honestly I have no idea how to get a file from the phone to somewhere you can access it.

[1 Lucky Texan]

doesn't sound like typical pinging to me. It should get worse with throttle demand as the ecu advances timing.

 

if we could see the knock data/correction, that might be helpful.

 

seems like you have plenty of experience though - just wonder what might sound like pinging at low load/rpm - is it a regular sound that tracks with rpm? is it a buzz/rattle or ????

[kkingcqe]

I've always said that engine ping is akin to marbles in a coffee can.  Subaru manual talks about a wrist pin issue that would happen under similar conditions but the description of the sound is different.  It is actually a knocking sound like you might hear with a bad bearing.

 

I'm thinking that timing correction is probably not mapped in the computer for these RPM/load conditions.  What I am saying is that the ECU ignores pinging sounds at this RPM and load.  That's what I am thinking.  Wish it would set a CEL, but the computer is happy. 

 

Once I push heavier on the throttle the sound disappears.  Whether it is gone or just masked by engine noise I don't know.  As I recall, when my big American V-8 engines pinged there was no mistaking the sound.  It was louder than the engine roar.

[1 Lucky Texan]

kinda wondering if you could have a weak timing belt tensioner. It can mimic rod knock and I guess piston slap, but it can smooth out at higher rpms where rod knock gets worse (this is all, 'usually' of course) but that isn't really 'marbles in a can', it's like a rhythmic knock.

 

I guess you've ruled-out loose heat shields? valve clatter? maybe an oil pressure test is needed?

 

if it does it at idles, or off idle with a helper, could you pinpoint L, R or front rear of engine?

 

maybe it is carboning-up quickly as GD said - he's a pro mechanic. maybe a PCV valve change would help with oil blow-by/control?

Edited October 23, 2017 by 1 Lucky Texan

[kkingcqe]

There is some heat shield rattle from the rear converter.  Sometimes it happens at the same time and the sound is a little different from the ping.  The mechanic put in $600 worth of parts on the timing belt change which I believe included tensioner(s).  The sound really isn't a knock although I tend to think of it that way, but I have heard bad rod bearings or collapsed hydraulic lifters and this definitely is not it.  I even had a mechanic at Meineke comment about how smoothly and quietly the car idles.  On occasion it does idle roughly but there is no rapping noise although it does tend to vibrate stuff in the door pockets.  My guess is that is the EGR not quite snapping shut.

 

PCV valve?  Far as I have been able to determine there is no PCV valve, but there is no problem with oil control.  The oil consumption is very low, in my opinion.  I don't expect to have to put any oil in between changes now that the leak is fixed. 

 

There was a lot of clean metal when I took a look at the pistons yesterday. More than I expected. I'm still planning on messing with the EGR when I get home tonight.

[1 Lucky Texan]

you have a PCV valve - on some years it's on the TB, other years it's on a head.

[forester2002s]

Your description doesn't match with 'pinging' AKA 'detonation'.

It's more likely a mechanical sound.

Perhaps from the camshafts?

If this was my car, the first thing that I would do is an oil and filter change. Might fix it.

[kkingcqe]

My first cars were built in the 1960s.  Lots of carbon buildup from carbureted induction systems.  You'll have to take my word that the noise is the same but not occurring at the same time.  I've been looking for a solution for this for some time and she's been through several oil changes during.  Mechanical knocking noises tend to have a more solid sound, if you know what I mean.  That and they get worse or at least speed up at higher revs. 

 

Got a couple of things to check when I get home tonight. 

 

I appreciate your input (and everyone else's) because one of these ideas is going to be the right one.

[GeneralDisorder]

Obviously I can't hear it so I have to go by your description but I have seen detonation from carbon and oil consumption. I just dealt with an 05 Forester with this problem. Oil consumption was around a quart in 1500 miles based on customer feedback. He had other shops put head gaskets in the car twice, and none of them suggested installing new rings to eliminate the oil consumption and stop the carbon detonation..... he's very happy with the results of piston skirt knurling, and new rings. 

 

It will not throw a code (ECU just assumes it's bad gas)  but you should see the knock sensor go nuts and pull timing if you have a scan tool that can see live data. Or an o-scope on the knock sensor. 

 

GD

Edited October 24, 2017 by GeneralDisorder

[Gloyale]

Hey.

 

Just a crazy thought.  (aka drunk)

 

What if the AVLS components on one or more valves are jammed in a way that the 2nd valve gets full lift always.?  Either mechanically or from a Oil Solenoid fault?

 

This would yeild more air, lean ratio, ping as timing and fuel are set for one valve per cyl full open off idle not 2?

Edited October 24, 2017 by Gloyale

[golucky66]

Anytime AVLS malfunctions, it throws a code very shortly after.

[kkingcqe]

I am battling a check engine light but it is for the front cat.  As a result of trying to clean carbon out of the cylinders I may have clogged my new catalytic converter.

 

I'm looking at the EGR system because it does have a certain logic that it may be the issue.  Yesterday there was a little pinging occasionally but nothing like Friday night when it was embarrassing to drive.  I had done a little cleaning of the EGR ports over the weekend so I did some more last night.  This afternoon I should have the opportunity to leave the windows down to listen for the ping echoing from roadside objects.

 

Thanks Tex for the tip on the PCV valve.  The shop manual never even mentions it.  I replace it last night, but the original one still rattles.  Yes I could tell that I was the first one to remove it in over 200,000 miles.