'08 v8 ping/slap/knock

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2fs2ns
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'08 v8 ping/slap/knock

Postby 2fs2ns » Sat Aug 13, 2011 10:40 am

65k miles on it, typically always have run 87 octane in it up until about 6 tanks ago when it started pinging/knocking pretty bad. And it wasn't a gradual thing, one day coming home from work there it was, I'd never heard it before at all. I've run some injector cleaner through once, didn't seem to really help at all. Plugs are the original platinum ones (I guess that's what's in there). Should I pull one and see if they're fouled? Will that cause the detonation?

Have I ruined it by always running 87 octane in it?

I've read about piston slap, but not sure if this is what I'm experiencing or not.

Here's a video with the sound, it sounds alot louder in person, you can barely hear it on the video I think.

http://youtu.be/wgOLG6nVMxM


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volvite
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Postby volvite » Sat Aug 13, 2011 7:12 pm

At 65K, I would look into changing spark plugs. The owners manual does say to use 91 Octane. When you use it, do you get the ping/knock?

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disallow
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Postby disallow » Sun Aug 14, 2011 3:06 am

Maybe get the knock sensor changed.

2fs2ns
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Postby 2fs2ns » Mon Aug 15, 2011 11:00 am

I'll look into the knock sensor, I'm not sure what that involves.

With 93 octane it still pings pretty good on moderate accelleration. You really have to baby it to keep it from pinging. I'm running another injector cleaner bottle through it now, still pinging.

Not sure if the audio in this video clip is any better...

http://youtu.be/EeqMfgF7TGM

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disallow
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Postby disallow » Mon Aug 15, 2011 11:20 am

2fs2ns wrote:I'll look into the knock sensor, I'm not sure what that involves.

With 93 octane it still pings pretty good on moderate accelleration. You really have to baby it to keep it from pinging. I'm running another injector cleaner bottle through it now, still pinging.

Not sure if the audio in this video clip is any better...

http://youtu.be/EeqMfgF7TGM
I used my bluetooth headset, and then I could hear what you are talking about. I don't think this is pinging. It sounds valve related. I've only heard of pinging like this on really hard acceleration, and you don't seem to be really nailing it...

Does this noise go away under certain load conditions? I thought I heard a decrease (or absence?) when you let off the gas...

Just wondering if its a stuck valve... how is the engine running otherwise? If its running well, I suggest some Lucas Upper Cylinder treatment. But if you think its causing damage, I'd get it to your trusted tech ASAP.

t

2fs2ns
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Postby 2fs2ns » Mon Aug 15, 2011 11:32 am

I only does it under accelleration, it does go away when you let off the gas. But I can be in in the driveway parked, hit the gas, and it will rattle/ping/whatever. Other than the noise the engine seems to be running pretty good. Maybe stronger smelling exhaust? But that's probably just in my head.

I don't know what a stuck valve really means, but doesn't sound good :) Could that explain the sudden onset of the problem and why fuel octane isn't helping?

I should probably get it checked out. I almost bought the lucas bottle this past time, but went with a different one.

NVRDONE
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Postby NVRDONE » Mon Aug 15, 2011 3:44 pm

I'm wondering if the noise isnt from worn timing chain guides. Seems early for them to wear out. Is the noise from the front of the engine ??

2fs2ns
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Postby 2fs2ns » Mon Aug 15, 2011 6:58 pm

I seafoamed it tonight via the master cylinder vacuum line. No smoke at all came out after sitting for about 10 minutes. Added some Lucas lubricant treatment to a new tank of gas too. Still same sound b

It doesn't sound like the front end, as a matter of fact it sounds like it's coming towards the rear of the engine, low. Could this possibly be from some kind of exhaust issue?? Could I be hearing something you normally just wouldn't? When I'm driving with the window down it almost sounds like it's right beneath me.

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volvite
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Postby volvite » Mon Aug 15, 2011 7:24 pm

Possible exhaust leak. However if you seafoamed it, you should have seen smoke coming out if there was a leak near the passenger compartment.

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disallow
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Postby disallow » Mon Aug 15, 2011 8:00 pm

2fs2ns wrote:I seafoamed it tonight via the master cylinder vacuum line. No smoke at all came out after sitting for about 10 minutes. Added some Lucas lubricant treatment to a new tank of gas too. Still same sound b

It doesn't sound like the front end, as a matter of fact it sounds like it's coming towards the rear of the engine, low. Could this possibly be from some kind of exhaust issue?? Could I be hearing something you normally just wouldn't? When I'm driving with the window down it almost sounds like it's right beneath me.
Maybe a leaky exhaust manifold gasket? I dunno man. I'd get it up on a hoist ASAP so you could at least rule out the simple and easy stuff.

I was going to suggest heat shields on your exhaust, but these sounds tend to change, and disappear as you get to different RPM ranges. Yours sounds more consistent than that.

2fs2ns
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Postby 2fs2ns » Tue Aug 16, 2011 7:31 am

I would tend to agree it's more than a heat shield too.

Would bad plugs be a possible source for this?

2fs2ns
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Postby 2fs2ns » Tue Aug 16, 2011 7:36 am

Is it a royal pia to pull a plug or two and check them out on this engine?

2fs2ns
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Postby 2fs2ns » Tue Aug 16, 2011 11:18 am

No codes so I guess it's not the knock sensor.

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disallow
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Postby disallow » Tue Aug 16, 2011 11:24 am

no, pulling plugs is not hard. You need a plug socket and an extension for your ratchet.

One caveat: I had some oil leak into the plug tube on one of my cylinders. This made it hard to pull the plug lead off of the end of the plug. So my advice is if it seems too hard to get the plug lead off, don't break anything. Stop and move to the next plug.

t


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