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Discussion Starter · #1 ·
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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Discussion Starter · #10 ·
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.
 

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Discussion Starter · #11 ·
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
 

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Discussion Starter · #12 ·
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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Discussion Starter · #16 ·
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.

 

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Discussion Starter · #17 ·
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.
 

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Discussion Starter · #18 ·
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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Discussion Starter · #24 ·
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'
Both of my motors have done this under these exact conditions, under no other conditions is there the typical piston slap that I am accustomed too.

.
Perfect on start up cruising, driving , beating on it ,
No knock , etc..

The only thing that sticks out logically to me is the pistons floating with no load @ over 2500rpm. Under this rpm it won't do it.
( thinking of down shifting and letting the motor slow you down , then putting just a touch of input on the peddle . This is the only condition it does it in.


It has everything to do with holding the gear with light throttle.
Most notable in 1-2 gear .
Maybe there in the others as well but can't pick it out with all the additional noise.
 

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Discussion Starter · #25 ·
I wouldn't even venture a guess without listening to it firsthand. No guarantees without looking at piston skirts and then measuring the pistons and bores. I'm not suggesting this but bearing knock and piston slap can also sound like one another at first. Worn rod bearings soon get a very distinctive sound and are most often noticed at a lower RPM. The second video in this thread was hard for me to hear what I wanted to hear except in one certain spot. It sounded to me like it had some top-end noise (valve-train) but from underneath I could hear a noise that I couldn't distinguish.

Years ago, I was building 400 Ford engines with 351 Cleveland parts. These were real runners they'd put down 500 usable street HP. These engines would really run with large port, big valve, closed chambered heads on them. We tried parts from several manufacturers including cams pistons etc. We had one that was running a TRW Forged Piston/Piston Ring pack.

This engine was built as well as human hands could put it together following parts manufacturers very closely. It developed a noise (later confirmed as piston slap and beyond) very early in its street life, just a couple of thousand miles. I saw serval of these go beyond 70,000 miles (that was respectable back then for a forged piston engine), including my father-in-law's F150 4X4. It had been broken in properly. Its cylinder-to-wall clearance was perfect according to TRW's specs.

This engine was disassembled it had literally broken the skirts in two cylinders but the break (upside-down triangle break) was such that the skirt was still going up and down with the piston. The cylinders were undamaged. After many discussions and mailing some parts back and forth, TRW re-designed this piston including additional skirt ribbing and a "thicker" ring pack. We ended up using custom Mahle's after this happened. I don't know if the problem was resolved. :LOL:

I'm telling a long story here but the thing is you could barely hear this noise at first and it ended up literally being broken pistons. Without revving it to a couple of thousand RPMs and backing out, most simply couldn't hear it. I couldn't hear it at a sustained RPM. It got louder but it wasn't like it was just slapping one day and broken the next, very subtle over a few weeks' time. These noises don't go away, they'll get louder. I'm sure that's more than any of you wanted to read. ;)

I read it .
It was valuable information.
.

this also helps to clarify to me this isn't the form of slap I am seeing here.
I am familiar with the sound of slap from to much clearance, this is only under" piston float conditions".
Something that these automatic f150s don't typically see.
By float I am referring to the exact point where it's not accel. Or decal, just holding rpm with no load.
 

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Discussion Starter · #26 · (Edited)
I wouldn't even venture a guess without listening to it firsthand. No guarantees without looking at piston skirts and then measuring the pistons and bores. I'm not suggesting this but bearing knock and piston slap can also sound like one another at first. Worn rod bearings soon get a very distinctive sound and are most often noticed at a lower RPM. The second video in this thread was hard for me to hear what I wanted to hear except in one certain spot. It sounded to me like it had some top-end noise (valve-train) but from underneath I could hear a noise that I couldn't distinguish.

Years ago, I was building 400 Ford engines with 351 Cleveland parts. These were real runners they'd put down 500 usable street HP. These engines would really run with large port, big valve, closed chambered heads on them. We tried parts from several manufacturers including cams pistons etc. We had one that was running a TRW Forged Piston/Piston Ring pack.

This engine was built as well as human hands could put it together following parts manufacturers very closely. It developed a noise (later confirmed as piston slap and beyond) very early in its street life, just a couple of thousand miles. I saw serval of these go beyond 70,000 miles (that was respectable back then for a forged piston engine), including my father-in-law's F150 4X4. It had been broken in properly. Its cylinder-to-wall clearance was perfect according to TRW's specs.

This engine was disassembled it had literally broken the skirts in two cylinders but the break (upside-down triangle break) was such that the skirt was still going up and down with the piston. The cylinders were undamaged. After many discussions and mailing some parts back and forth, TRW re-designed this piston including additional skirt ribbing and a "thicker" ring pack. We ended up using custom Mahle's after this happened. I don't know if the problem was resolved. :LOL:

I'm telling a long story here but the thing is you could barely hear this noise at first and it ended up literally being broken pistons. Without revving it to a couple of thousand RPMs and backing out, most simply couldn't hear it. I couldn't hear it at a sustained RPM. It got louder but it wasn't like it was just slapping one day and broken the next, very subtle over a few weeks' time. These noises don't go away, they'll get louder. I'm sure that's more than any of you wanted to read. ;)
I stand corrected.
This is starting to sound more like poor piston to bore clearance.
Sweet. And with only 250miles on it!!
🤦🏻‍♂️
I tried attaching a video so you could here and confirm but it says I don't have allowed extension.
 

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Discussion Starter · #28 ·
Upload video to YouTube and then post the "share link" in your post here.
The videos you see on this forum aren't actually hosted on the forum.
Awesome input,
Thanks for the proper method to use.
 
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Discussion Starter · #29 ·
I wouldn't even venture a guess without listening to it firsthand. No guarantees without looking at piston skirts and then measuring the pistons and bores. I'm not suggesting this but bearing knock and piston slap can also sound like one another at first. Worn rod bearings soon get a very distinctive sound and are most often noticed at a lower RPM. The second video in this thread was hard for me to hear what I wanted to hear except in one certain spot. It sounded to me like it had some top-end noise (valve-train) but from underneath I could hear a noise that I couldn't distinguish.

Years ago, I was building 400 Ford engines with 351 Cleveland parts. These were real runners they'd put down 500 usable street HP. These engines would really run with large port, big valve, closed chambered heads on them. We tried parts from several manufacturers including cams pistons etc. We had one that was running a TRW Forged Piston/Piston Ring pack.

This engine was built as well as human hands could put it together following parts manufacturers very closely. It developed a noise (later confirmed as piston slap and beyond) very early in its street life, just a couple of thousand miles. I saw serval of these go beyond 70,000 miles (that was respectable back then for a forged piston engine), including my father-in-law's F150 4X4. It had been broken in properly. Its cylinder-to-wall clearance was perfect according to TRW's specs.

This engine was disassembled it had literally broken the skirts in two cylinders but the break (upside-down triangle break) was such that the skirt was still going up and down with the piston. The cylinders were undamaged. After many discussions and mailing some parts back and forth, TRW re-designed this piston including additional skirt ribbing and a "thicker" ring pack. We ended up using custom Mahle's after this happened. I don't know if the problem was resolved. :LOL:

I'm telling a long story here but the thing is you could barely hear this noise at first and it ended up literally being broken pistons. Without revving it to a couple of thousand RPMs and backing out, most simply couldn't hear it. I couldn't hear it at a sustained RPM. It got louder but it wasn't like it was just slapping one day and broken the next, very subtle over a few weeks' time. These noises don't go away, they'll get louder. I'm sure that's more than any of you wanted to read. ;)

Ok figured out how to transfer information 😆.

I had to use the echo from the building to hear it.

It is only noticeable under the certain criteria I laid out for ya folks.
I have yet to be able to recreate it while driving it like a normal automatic.
And even free revving like I did in this video,I still needed to feather the throttle
If I were to blip it, it won't do it.
 
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Discussion Starter · #32 ·
So if you drive it normally no noise?
Sounds like an easy fix…
LOL!!

Yep,
As long as it's in automatic drive I cant seem to recreate it.

Although, it kinda defeats the reasoning dumping $25k into a truck you can't drive the way you want.


This has made a lot of questions rise for me.

Why did the old motor "seem" to do the same thing?

Is this what originally grenaded my old motor?

Is this something that can be tuned around. ?

Can others recreate it in their trucks?

The list goes on,
It's an interesting issue to find a solution for .
 
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Discussion Starter · #33 ·

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Discussion Starter · #36 ·
Torque converter?
If you haven't done so yet,
Give a listen to the video I attached and tell me your thoughts.
I put it on gear heads reply thread, but I'll stick it here as well.
Not sure if the video only pops up to him, or if it shares it with the whole thread.

As for the torque converter, it's solid, no issues that I'm aware of. I am not familiar with torque converts making the piston slap sound, but that doesn't mean much, if you have any links to a T.C vid. making that sort of sound I'd gladly compare it.

I had questioned it having something to do with the trans for a moment due to it only presenting it self in manual mode.
But after playing around learning how to recreate it.
I have my mind set on piston slap , perhaps due to crummy piston to bore clearance, or ..

As long as i don't the the Revs float it doesn't seem to happen, soooooo. Turn the snails dumpers up ta 22lbs. And dial the timing up to 20° and send er.!!??
🙃🤔


Idk, it's an interesting thing.
I'd love for it to be something else,

I have another 100miles left then I'm gonna put proper oil in it and see how much shiny we have in the old oil.
Not seeing any on the dip stick, but we'll see.
 

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Discussion Starter · #38 ·
Cracked flywheel?
I did give it a once over, but I didn't go over it with a fine tooth comb.

Your ears don't register it as piston slap?

This is an oddity .

I have to put it in a make shift echo chamber, i.e next to a wall or another car, garage etc..something for the sound to bounce off of and come back to my ears for me to even hear it, and even then it had to be @ the exact conditions mentioned.
As I fine tune my understanding of it I am realizing it comes on @ 2300-2500rpm and the clatter grows louder as the rpm goes up ( BUT, it has to be a no load condition) .
Like .15 -up to .35 .load, then as soon as a load ( in either direction is achieved it goes away).

In my mind I picture the piston rocking back and forth under the no load condition, kinda being floppy. ( this would be creating the slap )but as soon there is a load applied( and fuel and air, or the force from decel, it puts pressure on the piston, the piston then tilts putting pressure on the skirt to side wall and the slap goes away.


I have adjusted my driving style up, so that while I'm driving in manual mode I up shift quicker and keep the cruising( light right foot input ) rpm @ or under 2k. ( this and automatic driving keeps the slap away )

This experience has me questioning if it was my driving habit that stressed the old motor which weakened it leading up to the observation port being installed..


Thanks for your feedback,
It is greatly appreciated.
 

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Discussion Starter · #41 ·
I might hear piston slap but on an engine that new, I would think the noise would basically disappear when it got warm as clearances get tighter unless there were something broken. It's tough to diagnose when it's right in front of you but audio clips are really hard for me.

I am going to to pick up some proper sound equipment.
(( I have always been one to diagnose via sound, and this gives me a reason to invest in one the the audio kits that have multi location components.

I agree with you on sound clips being tough to hear what you are looking for.

I'm currently @ 431 miles. When I get home tonight I'm gonna be close enough to 500 that I'm gonna change the oil and see what we have to see.
( now from checking the dip sickle I've not seen a single spec of shiny, BUTTT💁‍♂️ we'll see)

As for the flywheel theory.
What type of damage would you expect to see that would allow this to make the deep hollow clatter sound @ only these very specific events/conditions?

This is the deal,
It feels, sounds, drives fantastic, the mileage is getting better each day.

And with only 10lbs, and no timing it feels stronger than my previous all out tune under the same driving conditions.


I'm on my 4th revision already and everything is spot on.

I've yet to go over 50% throttle and 4k rpm. Ok ok, I did push it to 4500rpm.once..., but in my defense , have you seen the parts list for this thing? It is begging me to flog it!!🤦🏻‍♂️😆🤣.


I also agree that this should be heard cold,
And then not so much once heated up,
And that's not the case.

This is just interesting.

Thanks again
Sometimes just collecting your thoughts in one place while getting the input from others really helps us to move forward.
 
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Discussion Starter · #42 ·
Here is a pic of the back of the motor( flex plate ) prior to installation, ( maybe if you zoom in something will stand out to you that doesn't stand out to me.
 

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Discussion Starter · #44 ·
A crack from one of the bolt holes either goes towards a vent hole, other bolt hole or towards the ring gear. I've also seen the crack go through to the center of the flex plate.

Just a side note as this was brought up earlier. Many of us old-schoolers use the term flexplate and flywheel synonymously when talking about an automatic transmission, they of course have their specific place. Flywheels are used with manual transmissions.

.
Just to clarify,
I wasn't attempting to correct anyone.
With my track record of miss labeling things that would be the ol' pot vs. Kettle debate.
.
I use parentheses when I am adding an additional thought or context too my thoughts or writing.

If I'm being completely honest I had to look up which name we use for the automatics, I've gotten those 2 confused for the last 25yrs.


I looked it over well enough before I installed it on the new crank that I would hope something like that would have stood out to me.
But I have over looked something before.
Once. ....🤣

.anywhos
Once I get the mic kit in I'll be able to make a Lil head way.

Being that it's specific condition dependant,
Maybe a harmonic resonace Yada Yada.
Etc etc.

I am no master engine builder.
I have been in the automotive world for 25+ yrs.
In some shape or another I did go to school for automechanics, I have built motors in the past,
And I did assemble these parts to make this brick move.
I'm only saying this, to hopefully add a little value to my piston float theory.

It's gonna be funny as all get out when I proven dead wrong, and humble enough to have a good laugh about it,
I really think there is something to it.
It's something that most 3.5 owners would never experience, and if they did it is so subtle and would rarely happen that it would never really register as something happening .


I only caught it this time ( and remembered it was something I wanted to look into with the old set up )
Due to me leaving an access port open in the fire wall.
Once I closed it up I could only hear it next to a wall.
 
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Discussion Starter · #45 ·
A crack from one of the bolt holes either goes towards a vent hole, other bolt hole or towards the ring gear. I've also seen the crack go through to the center of the flex plate.

Just a side note as this was brought up earlier. Many of us old-schoolers use the term flexplate and flywheel synonymously when talking about an automatic transmission, they of course have their specific place. Flywheels are used with manual transmissions.

That is the kit I was looking @!
Good man.😁
 
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