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Rattle back knock .

2561 Views 53 Replies 10 Participants Last post by  SrpRacing
Hey fellas/fella-ets,

Curious if this is a known quantity in the ecoboost world and if any of you have found a way to combats this .


Under very certain conditions I am experiencing rattle back knock ( piston slap )
It only happens between 25-3500 rpm.
ONLY while feather the throttle ( next to no input )
Goes with out saying, no load on the motor

And
Only while holding a gear in manual mode.

I have had it with both motors
Old and the new one,
Didn't think much about it with the old one,

However while breaking the new one in I am hyper sensitive to all sounds and vibrations while we get it sorted out.

The moment the slightest bit of load is added its gone.

I did just reach out to Torrie on the matter, but I thought I'd ask you folks if anyone has found a solution or Yada Yada, and etc. To this.


Thanks!
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Turbo waste gate rattle?
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Hey fellas/fella-ets,

Curious if this is a known quantity in the ecoboost world and if any of you have found a way to combats this .


Under very certain conditions I am experiencing rattle back knock ( piston slap )
It only happens between 25-3500 rpm.
ONLY while feather the throttle ( next to no input )
Goes with out saying, no load on the motor

And
Only while holding a gear in manual mode.

I have had it with both motors
Old and the new one,
Didn't think much about it with the old one,

However while breaking the new one in I am hyper sensitive to all sounds and vibrations while we get it sorted out.

The moment the slightest bit of load is added its gone.

I did just reach out to Torrie on the matter, but I thought I'd ask you folks if anyone has found a solution or Yada Yada, and etc. To this.


Thanks!
I think Justinjs is on it, I bet you 100$ is turbo wastegate rattle or NVH. I have Turbo wastegate rattle on my stage 2 turbos, and I had it on my old turbos. I’m not sure I have heard an Ecoboost that doesn’t have some sort of rattle like that. The raptors have some kind of NVH noise that’s very noticeable too.
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Could you put a couple of springs on the wastegate actuators to temporarily put a soft load against the slop in the linkage, and then go test to see if the sound is diminished or gone? Just to rule it out?
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Could you put a couple of springs on the wastegate actuators to temporarily put a soft load against the slop in the linkage, and then go test to see if the sound is diminished or gone? Just to rule it out?
I’m not sure you could, the noise can be internal, inside where the flapper is. It’s usually in there and on the outside where it links to the elbow piece.
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Ahhhh. That makes sense. I was just hoping that "slop" was attached to the external linkage.
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Pretty sure I've got this too. It only happens before I get to operating temperature.

Is the waste gate rattle something to be concerned about? At least if a wastegate falls apart the chunks hit the Cats and not get sucked into the intake right?
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Pretty sure I've got this too. It only happens before I get to operating temperature.

Is the waste gate rattle something to be concerned about? At least if a wastegate falls apart the chunks hit the Cats and not get sucked into the intake right?
Yeah. Haha, no, it’s not like it’s a super bad thing, just kinda obnoxious. It just means the linkages aren’t as tight as they used to be. It still functions just fine and probably will for a long long time, but it rattles like a little rattle snake under there. I’ve never heard of anything coming apart. If it did, then yeah you’re right, it would just go into the cat, and the wastegate would be wide open so you wouldn’t blow your engine up or anything.
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Here's a video of what's going on.
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Ahhhh. That makes sense. I was just hoping that "slop" was attached to the external linkage.
I think it's possible to test your theory out.
I could lock them out and see.

However they are brand new and have no slack what so ever and have a much higher tension strength then my old turbos and waste gates.
Here's a video of what's going on.
This is a brand new motor and turbos.
I checked the values on both old and new turbos before I installed the motor .

Nothing loose all solid and super tight
Sound theory,
but
In this case this isn't wastegate rattle.

This happens at any temp.
((( but only under these exact conditions) )
ONLY under no load, 2500-3500rpm.
Holding a gear in manual
And feathering the throttle down to almost no input.
And it sounds almost like starting a diesel cold.
(Piston slap) there is a name for it. Something something back rattle knock etc.etc.

It's the pistons more or less free floating @ the exact rpm with out and work being done.
And the piston rocks in the bore.

I am trying to see if this is something folks have tuned around in the past. Just ignore it .

I am wondering if it's a parameter in the original software that a tuner would never look at, and just wasn't quite sorted from the factory.

It's only in manual mode

It did this with the old motor too.
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This is a brand new motor and turbos.
I checked the values on both old and new turbos before I installed the motor .

Nothing loose all solid and super tight
Ah. I missed that part.

Your other motor did the same noise?
Who built the motor?
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Sound theory,
but
In this case this isn't wastegate rattle.

This happens at any temp.
((( but only under these exact conditions) )
ONLY under no load, 2500-3500rpm.
Holding a gear in manual
And feathering the throttle down to almost no input.
And it sounds almost like starting a diesel cold.
(Piston slap) there is a name for it. Something something back rattle knock etc.etc.

It's the pistons more or less free floating @ the exact rpm with out and work being done.
And the piston rocks in the bore.

I am trying to see if this is something folks have tuned around in the past. Just ignore it .

I am wondering if it's a parameter in the original software that a tuner would never look at, and just wasn't quite sorted from the factory.

It's only in manual mode

It did this with the old motor too.
My wastegate rattle happens at any temp as well.
But, you might be dealing with NVH. Is there a metal heat shield buzzing against something that you can see?
What's the knock sensors saying in that exact scenario?

Fortunately it isn't normal to be at 3000rpms no-load.
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My wastegate rattle happens at any temp as well.
But, you might be dealing with NVH. Is there a metal heat shield buzzing against something that you can see?
No.
This is not a tinni sound .
It sounds like a diesel. It's a hollow sound.
This is a sound clip of piston slap.

What's the knock sensors saying in that exact scenario?

Fortunately it isn't normal to be at 3000rpms no-load.
What's the knock sensors saying in that exact scenario?

Fortunately it isn't normal to be at 3000rpms no-load.
You are correct, it's a fault in my driving style,
I caught it happening while doing an arch with the rpm range while holding a gear. 1k up to 3k and slow throttle up then down.
on the decel it appears that the piston floats, then slaps a bit. ( diesels )
.
Nothing.
It's appears that it's not within its frequency range.
Nothing in the logs show up either.
Ah. I missed that part.

Your other motor did the same noise?
Who built the motor?
I bought a long block from a co. Called go power train.
Then put everything together myself and installed it.

Yea,
This was something I had started noticing before on my old motor.

And it has to do with my driving style using the manual valve body for shifting.
I noticed it while driving a certain way.
Holding the gear @ one rpm between 25-3500 rpm.
Light throttle input.
Basically it's the piston floating and slapping the bore.
Under normal driving the motor would never experience this because it will automatically shift.
.
But say you use the manual to down shift then lightly feather the throttle it will do it.
Not accelerate mind you. Just enough to maintain rpm speed. Then it'll float
.
Seems like something over looked in the programming of the factory tune.
And never gets touched by a tuner, cuz you know, why would they unless asked .

Just thinking out loud here.
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Piston slap (not to be confused with detonation or pre-ignition) is most likely to be heard in an engine that has forged pistons or one that was set up with the wrong piston to bore clearance or flat worn out. If they have the wrong clearance they can make noise from the get-go. Which one of these fits the bill? Just sayin'
What's the knock sensors saying in that exact scenario?

Fortunately it isn't normal to be at 3000rpms no-load.
No.
This is not a tinni sound .
It sounds like a diesel. It's a hollow sound.
This is a sound clip of piston slap.

hmm, interesting. I may have that on my truck too, just initially on startup I’ll get a very similar sound.
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