Piston Slap: Feelin' Love For Forums, Check Engine Lights

Sajeev Mehta
by Sajeev Mehta

TTAC Commentator Detroit-Iron writes:

I have an ’09 Subaru Legacy with 26.5k on the clock. I drive close to 600 miles a week, all on main road or highways at a steady 75 mph with few exceptions. It is pretty warm where I live now, but it is not dusty here in the mid Atlantic, way too much humidity, and my direction of travel means I rarely run into traffic. Recently I got a CEL, I took it to Advance auto but the guy couldn’t find the port. The next morning the CEL was gone, but after work it had come back. I tried filling the gas and re-tightening the gas cap to no avail. Ominously it also developed a rattle at 3k rpm. After I got home (120 mile trip with no cruise control) I went back out to the store that evening and the CEL was gone. The next day I took it to a dealer who didn’t have time to diagnose but said he would take if for a quick spin.

When I told the mechanic about the rattle he looked at me like I had just said that I enjoy biting the heads off of puppies because he “never drove a car over 3k rpm.” Of course, the car turn 3k at 72 mph, so I don’t know where he drives. Anyway, he said that the rattle was just a loose heat shield (he did not look under the car to confirm, because he had been a Subaru mechanic for 17 years and didn’t need to). When I was driving over to the dealer I notice after going around a sharp cloverleaf that the CEL (which had not been on) lit up. The next day I babied the car to work and the CEL did not light. On my way to dinner that evening I confirmed that a sharp turn would cause the CEL to light up. I finally got to a different dealer to diagnose for reals the following day. After looking at it briefly he said that there wasn’t any oil in it, or at least not enough to even touch the dipstick. They changed the oil, ran it for a while, and changed it again. The CEL has not returned but the rattle never left.

I always run synthetic oil, partly because I am pretty lax about getting it changed. Usually I buy Mobile 1 from Wal-Mart and get it changed at Jiffy Lube. The last time I was at Jiffy Lube I just told them to use their synthetic. When this started there had been 9600 miles since the last oil change. The vehicle is not leaking any oil at all, and the oil pressure light never came on. Although I knew I needed a change (and if fact was planning on getting it done the day the CEL came on), considering that I drive almost exclusively on the highway, I didn’t think 9600 was entirely unreasonable. The dealer said that synthetic or not, it should be changed every 3750.

What say you? Did I ruin it? Should I toss it in the garbage and get a new one? Any idea why the oil pressure light never lit up? Do you think Jiffy screwed me and just used conventional?

Sajeev Answers:

Hey man, thanks for writing again. Love my “frequent flyers.” Unfortunately that dude at the dealership is right; Subaru recommends oil changes (turbocharged models only) every 3750 miles. Which sounds all kinds of wrong to me.

Maybe Subaru is recouping their crippling warranty claims via oil changes, instead of making their owners pay for thrashing their complex boxer-turbo-manual-AWD products? That would explain the NASIOC’s sub-forum created to handle warranty denials. Not that I cruise every car forum on the planet, but this looks like a Subaru-only kind of concern. Well maybe Nissan GT-R folks feel your pain, too.

But I don’t see anything wrong with your actions. I just don’t see your oil changes causing engine rattles, but maybe a CEL will make me change my tune. I’m gonna ask you for the code(s) that caused a check engine light. This makes whatever I write far more accurate and relevant.

Detroit-Iron writes:

Okay, I got the codes: P0026 and P0028, both are about the intake valve solenoid. I think they correspond to the RH and LH cylinder banks. I also determined that the rattle has less to do with RPM than throttle position. Anything over 2k, if I just lightly step on the pedal

Thanks for making me get the code. I was pissed off about the whole situation and didn’t really want to talk to the mechanics again, but that is obviously not a productive way to think.

Sajeev Answers:

As predicted, with those codes, my tune won’t change: you didn’t ruin the car. If only the rest of our lives could be solved so easily. Imagine sticking an OBD-II code reader into your significant other’s…umm…”test port” when they act bizarre. And if only your co-workers came with Check Engine Lights!

And with those codes I used the “search” feature on NASIOC to find this thread. Not being a boxer expert by any means, I feel this is your problem. The solenoid(s) could be loose or the timing chain/tensioner could be at fault.

So post your question and hypothetical solution on a Subaru forum like NASIOC. Once you get savvy, wholly independent minds on the problem, take it to a mechanic as an informed consumer. I suspect it’s time to drop a subframe and tear that motor apart.

Send your queries to mehta@ttac.com

Sajeev Mehta
Sajeev Mehta

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  • Ronnie Schreiber Ronnie Schreiber on Aug 19, 2010
    “and the oil pressure light never came on.” - If you ever see the low oil pressure light come on, its usually too late anyways. I don't know how there could be low enough oil pressure to trigger a CEL and not light up the Oil Pressure indicator. BTW, the term "idiot light" may not be sufficient. A short while ago a friend of my son gave me a lift to the bank. On the way home I noticed his oil pressure light was on and despite everything I told him about having to stop and get oil immediately, he kept saying "I guess I have to take it to my guy." Even after I showed him the dry as a bone dipstick when he dropped me off at home, he still wouldn't go buy oil. He's not stupid, actually he's pretty book smart, but some folks are convinced that they can't do anything on their cars.
  • George McNally George McNally on Aug 26, 2010

    We've had 3 Subies over the past 20 years (still have 2 of them)...the only 2 things I can recommend are to change your oil more often and find a really good non-dealership mechanic to work on it. We are lucky and have a garage nearby that only works on Subaru's. he's not a whole lot cheaper then the dealership, but I trust every word that comes out of his mouth.

  • MaintenanceCosts It's not a Benz or a Jag / it's a 5-0 with a rag /And I don't wanna brag / but I could never be stag
  • 3-On-The-Tree Son has a 2016 Mustang GT 5.0 and I have a 2009 C6 Corvette LS3 6spd. And on paper they are pretty close.
  • 3-On-The-Tree Same as the Land Cruiser, emissions. I have a 1985 FJ60 Land Cruiser and it’s a beast off-roading.
  • CanadaCraig I would like for this anniversary special to be a bare-bones Plain-Jane model offered in Dynasty Green and Vintage Burgundy.
  • ToolGuy Ford is good at drifting all right... 😉
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