Rotational grinding sound - turbo? Please weigh in.

[TapTapPull]

In June I noticed a noise from the engine. I'm wondering if anyone can help with tracking it down. I suspect turbo impeller. This is my first forced-induction vehicle so I appreciate any insight:

There is an audible, rotational metallic grinding noise after low load in the first, second and third gears. EDIT: it could be present in higher gears but road and wind noise drown it out. It occurs low in the RPM range, and is most prominent after letting off the gas.

Now, I don't know a ton about turbos, but to me it feels like if you give the car enough gas to start start the turbo to spool and then let off, that as the impeller begins slowing down again, it is wobbly/loose and grinding around. Doesn't really sound like any debris rattling around, just like a rotational grinding. You do not need to add enough gas to generate any noticeable boost. Imagine the amount of gas you'd use navigating a parking lot. These are the speeds and amount of throttle needed to generate the noise.

I tried to take a video while in a parking garage and will upload it tonight.

I asked Ford to look at it while they did some brake work and they said they couldn't hear anything. I took the head tech (pretty sure that was his title?) for a drive around the lot and tried to show him the sound and after talking to some of his techs he told me that there was nothing wrong, and that when turning + accelerating under low load/low speeds, that you need more power and that the turbo kicking it is normal. Which may be true, but the sound is not "clean" or good, and certainly wasn't present when I bought the vehicle. He told me to continue to drive and monitor it and if it got worse to notify them.

I am 99% sure this is any sort of resonation/vibration issue at a certain RPM range. It sounds like a mechanical wear noise.

Here are the details of the vehicle:

2014 FiST, about 26,000 KM on the odometer (16,000 miles).

Mods that might play a factor (Aside from the slightly more aggressive OTS tune as a catalyst, I don't think they'd generate this noise?):
COBB AP 91 octane tune (vary between 91 octane and 94 octane fuel (Chevron gas))
mountune high flow induction hose
mountune short shift kit
mountune roll resistor
boomba racing shifter base bushings

Any thoughts?

 

[CanadianGuy]

Can you hear it when no load rev? Or must the car be moving to hear it? If you can reproduce without the car moving trying recording it and posting. Some may hear and explain.

 

[TapTapPull]

Pretty sure the car must be moving. I can't have it in neutral and apply throttle/revs to recreate the sound. Good question.

I double checked the video my passenger took and the sound is pretty prevalent. Will be uploading it tonight after work.

EDIT: I appreciate your interest and realize a video is going to be the best information for anyone who cares to guess at the issue. I'll get the video up ASAP.

 

[me32]

Its hard to say its the turbo. Cause it would be on going not just in gears 1-3. I would put the car back to stock an go from there.

 

[TapTapPull]

Its hard to say its the turbo. Cause it would be on going not just in gears 1-3. I would put the car back to stock an go from there.

It might be there in higher gears, but road and wind noise drown it out.

The point about it not being present in neutral could mean not turbo, though.

Transmission? Video soon.

 

[TapTapPull]

Here's the video:

https://youtu.be/u628j5yHy4s

 

[tjd_tdi]

Hmm. Is it happening when you go off throttle or when you on throttle? It's really hard to place in that video.

 

[TapTapPull]

After throttle. Add throttle to get it moving, and once you lift off, you get the noise.

 

[tjd_tdi]

After throttle. Add throttle to get it moving, and once you lift off, you get the noise.

So, to me, it faintly sounds like the turbo spooling down off throttle. Sort of like this, but not as dramatic: https://youtu.be/Gn-AoxKQB90?t=33 (yellow car, should be queued up in link)

I know when I went to the 2J intake (which is obviously extreme in terms of induction noise), I could hear a lot more turbo action, including that spool down sound.

 

[TapTapPull]

So, to me, it faintly sounds like the turbo spooling down off throttle. Sort of like this, but not as dramatic: https://youtu.be/Gn-AoxKQB90?t=33 (yellow car, should be queued up in link)

I know when I went to the 2J intake (which is obviously extreme in terms of induction noise), I could hear a lot more turbo action, including that spool down sound.

It sounds nowhere near as 'clean' or as deliberate as your video, but it does occur after letting off throttle, during a window where spooling down might be occurring.

Again, I don't really know tons about turbos; does the fact I can't recreate the noise while in neutral and stationary mean anything?

There's also a sweet spot of add throttle+ let off to make this occur. Add too little and it won't make it (I feel like this is because the turbo didn't get to spool). Add too much and I think the turbo spools fast enough to straighten out and not rattle. What's weird is that you'd think that once a really spooled and rotating impeller slowed down to that 'sweet spot' it would make the noise, but it doesn't appear to, really.

I know the video isn't great. I'm going to try and get a better quality one this weekend.

 

[tjd_tdi]

It sounds nowhere near as 'clean' or as deliberate as your video, but it does occur after letting off throttle, during a window where spooling down might be occurring.

Again, I don't really know tons about turbos; does the fact I can't recreate the noise while in neutral and stationary mean anything?

There's also a sweet spot of add throttle+ let off to make this occur. Add too little and it won't make it (I feel like this is because the turbo didn't get to spool). Add too much and I think the turbo spools fast enough to straighten out and not rattle. What's weird is that you'd think that once a really spooled and rotating impeller slowed down to that 'sweet spot' it would make the noise, but it doesn't appear to, really.

I know the video isn't great. I'm going to try and get a better quality one this weekend.

So, I'm going out on a limb with my own knowledge of turbos and would ask other more knowledgeable members to weigh in. But, I think the fact that there's a sweet spot might relate to the blow off valve. The way I understand it, when you create boost--pressurizing IC and all the piping post turbo--then get off the throttle, the car wants to get rid of that pressure. That's where the BOV comes in and releases the pressure. If you don't create quite enough pressure to trip the BOV, then it may be rushing out back past the turbo and out the intake. That's what I *think* the noise from the video is, though again, I'd want some confirmation.

 

[J2FoRS]

Mine does this noise....sort of. Usually in 6th around 80-85km/h crising about. While under light throttle it's not there, but if you let off you hear it then it stops when you get back on it. I thought it was the turbo down spooling due to the BOV not dumping off such low pressure.

Now I'm interested.

 

[tjd_tdi]

Mine does this noise....sort of. Usually in 6th around 80-85km/h crising about. While under light throttle it's not there, but if you let off you hear it then it stops when you get back on it. I thought it was the turbo down spooling due to the BOV not dumping off such low pressure.

Now I'm interested.

Yep, that's exactly what I was trying to describe.

 

[Hijinx]

When you can (if you haven't already), crank down on all of your clamps and see if that helps.

 

[TapTapPull]

I really appreciate the discussion. I'll check my boost clamps as soon as I can.

 

[sdewolfe]

I know the sound you mean because mine does it too. I have had other turbo cars and this is not a normal turbo sound. I cannot say it is the impeller that makes the noise but it certainly is turbo related. It happens under no- or low-load conditions. It started at 2000 miles so slight I could barely hear it. But it is getting progressively more pronounced as the miles rack up. Louder during morning drive away for my daily commute. Watching this thread.

 

[TapTapPull]

Got under my car two nights ago (finally).

Tightened the clamps using the picture guide posted on this thread (search for "boost clamps"). At least four of them took a fair amount of ratcheting. Nothing finger-loose, but not ratchet-tight, either.

Sound might have been minimized, but is still present.

Maybe I didn't get all of the clamps?

Definitely feels like I got some boost back, however. Before my AP read 18-20.25 PSI max. I stupidly stepped on my AP two weeks ago and damaged the screen so it is sent off to COBB for repair. Cannot verify that I've got some lost boost back, but it certainly feels like I have. I'll verify after COBB repair my AP.

I'm going to look into other issues, and have some local, knowledgeable people take a look and weigh in over the next few weeks.

 

[doctorweird]

Has there been resolution on this? I'm experiencing the same sound

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[TapTapPull]

Has there been resolution on this? I'm experiencing the same sound

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From what I've gathered, it is not something to be concerned about. I've learned to live with it. I heard it to a lesser-degree in a friend's FiST, also.

Ford techs didn't acknowledge the sounds as anything to worry about.

 

[doctorweird]

Ok, I just thought it was odd. Never heard it till I hit 1700 miles, and suddenly there it was.

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