Intake Thump - Thoughts?

[ou18]

Hello all, hope everyone is healthy. I have a odd sound. On my 2017 Mustang GT with the JLT CAI and Tune, I noticed recently while jump starting my pickup, that I had this odd thump. It sounds like it is in the intake tube to the throttle body. Obviously there are no moving parts inside the tube. So something is creating the noise and the tube is acting like bass tube.

Odd Intake Tube Thump

It can be hard to hear, but it happens multiple times
1st - at 11 seconds
Then repeats at 16, 19 and 22 second mark.

I'm having a hard time identifying where it originating from. I THINK, it is coming from somewhere around the TB (which is stock and manifold is stock). Ive read other posts in regards to people having issues with TB. But couldnt locate a good video of the sounds being made. I also dont have any idling issues that I can tell. It idles fine, car seems to drive okay. It has been rather hot here in SFLA the last few days, today it seemed a bit sluggish on light throttle. Havent stalled out at all. Or seen a noticeable drop in RPMs. I've also read people stating the purge valve?

Happens regardless if A/C is on or off. And does not go away with driving. Pretty much is there all the time, however the frequency of it seems rather random.

Thoughts from the forum on what it could be?

Regards
Steve

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[Ninpop9]

With tunes sometimes a excess build up of carbon happens on the other side of the throttle body, you could try taking off the throttle body and seeing if there's any debris there. It's a odd noise for sure.

 

[ou18]

With tunes sometimes a excess build up of carbon happens on the other side of the throttle body, you could try taking off the throttle body and seeing if there's any debris there. It's a odd noise for sure.

I was planning on pulling the CAI off to check if that plate is gunked up, also just good maint to keep it clean. Running a 93 tune on the car currently.
Thanks for the input on it. I think the intake tube is definitely amplifying whatever is causing it.

 

[NeedForGreen]

I know someone who had this happen with a different CAI. Ended up being a bad throttle body. Sounded like the tube, but was the throttle body.

 

[ou18]

I know someone who had this happen with a different CAI. Ended up being a bad throttle body. Sounded like the tube, but was the throttle body.

Yeah, the sound doesnt come up well on the video with all the background noise happening. But has a hollow sound to it, this will sound funny, but almost like a bongo player tapping on the bongo just enough to create noise. Thats about the tone of it. No Im not a musician.

TBs are cheap enough. The ford performance one from the GT350 seems a capable replacement, but have been reading stories of Bama tune having a horrid time with them. Not sure if they worked this out, will have to check with them. Some rendering the car useless. The JLT CAI I bought came with the Tuner and free tunes. Before anyone crucifies me, I dont race, I dont track. I just enjoy the car as a daily driver. So this was a good deal for me in case I wanted to add smaller items that would require a tune change later.

Any thoughts on the GT350 TB? I know everyone has differing opinions on different parts and what they feel is the best. Trying to keep it somewhat budget friendly as well.

Thanks for the input

 

[ou18]

Update - so, went out to the car, took about 5 minutes. First when I went to go remove the CAI tube to TB, oddly enough, one of the clamps was not tight, I was able to turn it by hand, wierd. So I proceeded to pull the tube off the TB. Mine might be a case of it sticking. I can see some carbon deposits around the valve, and if I peer under that, i can see a decent amount of carbon build up. So before I go buying a new TB, Im going to pull this one off and give it a good cleaning this weekend. Good maint anyway. Just thought I'd share, only time will tell if that corrects the issue.

WIll update once I have cleaned up the TB real good and reinstalled at some point this weekend.

 

[ou18]

Update 2 - Went and bought a new gasket for TB. Local Dealer had one, figured if Im taking this thing off, might as well replace gasket. Pretty simple procedure , not much to it. Alot of people said getting the electical connector off the motor was hard. I just took the TB off the Manifold first so I could pull it clear of everything else and it came right off.

In any event, cleaned up the TB really good. All deposits removed. Nice and shiny clean so air flow is nice and smooth. Cleaned the MAF while I was at it. Put it all back together. As soon as I started it, i heard the thump a few seconds later. Took it for a drive. Opened the hood, and heard it again, It doesnt seem as frequent but its still there. So Im kind of stumped.

Is the TB going bad? Could it be something else? Normal Operation? Some kind of purge valve?

Dont want to just buy parts randomnly hoping I fix it with one of them..

Thanks for any and all input. Its greatly appreciated..

 

[gpbentley]

Did you ever figure this out? Just starting hearing the same noise today

 

[SheepDog]

Might be the IMRC valve actuator. The shaft breaks and cant control the valves anymore

 

[ou18]

Did you ever figure this out? Just starting hearing the same noise today

i did not every figure it out, and honestly havent noticed it in some time.

 

[gpbentley]

Might be the IMRC valve actuator. The shaft breaks and cant control the valves anymore

I have my imrc locked out so I don’t think that would be the issue, any other ideas? I appreciate it very much… driving me crazy

 

[boB]

The "bongo" noise sounds like it could be an HVAC actuator/door or maybe an EVAP valve.

 

[K4fxd]

On the stock CAI there is a trap on the bottom. This is a Helmholtz resonator. This stops the noise you are hearing with your aftermarket CAI.

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