Loud whistle after installing JM FAB intake manifold

[19BLACKGST98]

Anyways like the topic says I now have a really loud whistling sound under my hood after an engine build with the addition of a JM fab intake manifold and a 75mm throttle body (it is so loud I can hear it while I am 100+ feet away with the hood down). The sound goes away after the RPM's go above 2000 or so. There is NO boost leaks (it has been tested for most of a day and the throttle body has been sealed twice) I know the problem sounds like a boost leak but its not. Does anyone have any suggestions about what it is or how to fix it (other than telling me its a boost leak)?

 

[the_mork]

If I had to guess I would expect that it is a tiny slice of metal sticking into the air path somewhere and acting like a reed.

 

[19BLACKGST98]

If I had to guess I would expect that it is a tiny slice of metal sticking into the air path somewhere and acting like a reed.

He said he was going to take it off and check it out and make sure everything is how it should be. I hope I dont have to get another SMIM.

 

[1gDSM4g63]

Where is the source of the whistle and does it do it when the car is complete idle?

 

[19BLACKGST98]

It sounds like its coming from around the intake manifold (it is really loud and Ill get video of it next time I go over to his shop)/throttle body area and yes it does it when the car is just idleing and anywhere under 2,000 RPMS.
He believes that after 2,000 RPM it gets more high pitched like a dog whistle thats why we think it goes away.

 

[dsmfa9nutter]

Your smim didn't seal to the head correctly OR your injector seals aren't sealing OR you have a vacuum hose that isn't on the barb tightly. At around 2k, your turbo should be spooling just enough to equalize the air pressure in the intake, no air sucking in=no whistle.

 

[xdxoxuxgx]

Aren't JM Fab SMIM known to be loud anyway?

 

[badas93tsi]

Aren't JM Fab SMIM known to be loud anyway?

At idle, my JMF mani sounds like there's a massive vaccum leak. Boost tests fine. As far as a whistle, who knows.

 

[19BLACKGST98]

At idle, my JMF mani sounds like there's a massive vaccum leak. Boost tests fine. As far as a whistle, who knows.

Yes I know other people that have them on their 2g's also and they are alot louder than stock, but nothing like what mine sounds like. Before he started the car for me after it was rebuild he said get ready to be annoyed and he was right..

 

[xloki77x]

I actually had the same problem in a 97 maxima. I swapped intake mani's for a variable runner mani and it also had a very loud whistle. No one could figure out what it was. I ended taking the IM off and it was the IM gasket that wasnt seated properly and was making the whistle.

Pete

 

[VETTE_50_TH]

My car did that too. I didnt see the TB to the intake well enough and it had a nice little whistle to it. You could see the gasket fluttering. It was kinda funny. I would def check a gasket first before anything.

James

 

[19BLACKGST98]

Thanks guys he said that he is taking it off and putting a new gasket on. Im sure it will cost me more money but it will be worth it.

 

[19BLACKGST98]

I actually had the same problem in a 97 maxima. I swapped intake mani's for a variable runner mani and it also had a very loud whistle. No one could figure out what it was. I ended taking the IM off and it was the IM gasket that wasnt seated properly and was making the whistle.

Pete

My car did that too. I didnt see the TB to the intake well enough and it had a nice little whistle to it. You could see the gasket fluttering. It was kinda funny. I would def check a gasket first before anything.

James

Neither one of you had boost leaks? I would think something like that would show up on a boost leak test?

Thanks everyone for the helpful replys. Ill let yall know if changing the gasket fixes anything.

 

[VETTE_50_TH]

Neither one of you had boost leaks? I would think something like that would show up on a boost leak test?

Thanks everyone for the helpful replys. Ill let yall know if changing the gasket fixes anything.

Yes. I did have a major boost leak. The sound was present when i was in vacuum but you could here when boost came in.

James

 

[xloki77x]

Neither one of you had boost leaks? I would think something like that would show up on a boost leak test?

Thanks everyone for the helpful replys. Ill let yall know if changing the gasket fixes anything.

I had it in a 97 maxima VQ30...NA. But I would imagine that would come up during a boost leak test.

 

[19BLACKGST98]

Well I had the intake manifold taken off and had a new gasket put on. Everything was taken off and re-sealed but the damn whistling sound is still there. It has to be the JMF Manifold. Does anyone else here run this manifold with a 75mm throttle body? (PS: Still not boost leaks)

 

[dsmfa9nutter]

Run the car and spray starting fluid along the welds, if the idle changes, you've got a hole/crack in a weld.

 

[19BLACKGST98]

Run the car and spray starting fluid along the welds, if the idle changes, you've got a hole/crack in a weld.

Would that not show up on a boost leak test? This damn thing is brand new I hope it doesnt have any cracks along the weld. I dont know if they replace their faulty manifolds?

 

[VETTE_50_TH]

Would that not show up on a boost leak test? This damn thing is brand new I hope it doesnt have any cracks along the weld. I dont know if they replace their faulty manifolds?

Yes. JM FAB will repair a faulty or replace a bad weld if that is the case. They test everything they sell but sometimes shit happens. I would run a boost leak test and see where it is coming from.

James

 

[thewombis]

Completely normal, there are forums all over about this phenomenon. My friend installed the same intake on his 2G, and we searched a long time to find that whistle sound. After reading many posts that were similar we ruled it out as normal. No running problems, no leaks. at idle its really loud, and you can hear him coming down the road from quite a distance when hes going 10-20mph. Kinda funny, I would not worry about it unless you know there are problems. If it was a leak, i would think you would notice the idle to be a little off.

Run it, leak test it, if nothing is found.. its normal!

***oh, he also has a 75mm TB

 

[19BLACKGST98]

Completely normal, there are forums all over about this phenomenon. My friend installed the same intake on his 2G, and we searched a long time to find that whistle sound. After reading many posts that were similar we ruled it out as normal. No running problems, no leaks. at idle its really loud, and you can hear him coming down the road from quite a distance when hes going 10-20mph. Kinda funny, I would not worry about it unless you know there are problems. If it was a leak, i would think you would notice the idle to be a little off.

Run it, leak test it, if nothing is found.. its normal!

***oh, he also has a 75mm TB

Yea its normal. I will be changing Manifolds to a Magnus because they dont have this issue.
The 75mm throttle body makes it much loader. I know people that have this with 1g throttle bodies and it isnt anywhere close to being as loud as mine.

**Boost leak test was performed probably 20 if not more times with no leaks**

You really can hear this noise from hundreds of feet away if the idle is below 2k

 

[Defiant]

You really can hear this noise from hundreds of feet away if the idle is below 2k

Sounds like a leak that's only noisy at high vacuum. What about when you let-off the throttle and coast down from speed?

Has the throttle body been matched to the manifold flange? Was the manifold matched to the head?

 

[19BLACKGST98]

Sounds like a leak that's only noisy at high vacuum. What about when you let-off the throttle and coast down from speed?

Has the throttle body been matched to the manifold flange? Was the manifold matched to the head?

I dont have the car back yet because im having a few other things done (3" GM Maf is getting moved to the intake pipe, getting a resinator cut our of my exhaust, Getting bigger/new piping for the intercooler...I think thats it) So I dont know if it makes the noise when coasting.

Yes the throttle body has been matched to the manifold and the head was ported to match the manifold.

 

[19BLACKGST98]

The whistle is gone!!! Well after my GM maf was moved to the turbo inlet and a new UICP was made the whistle has went away. I guess I wont be needing a new SMIM now. Thanks everyone that helped with this problem.

PS: Thewombis: tell your friend the same thing and maybe it will work for him.

 

[BoredDSM]

The whistle is gone!!! Well after my GM maf was moved to the turbo inlet and a new UICP was made the whistle has went away. I guess I wont be needing a new SMIM now. Thanks everyone that helped with this problem.

PS: Thewombis: tell your friend the same thing and maybe it will work for him.

Actually this is very strange. On recent testing of JMF manifolds there have been reports of some turbulence with there manifolds. By adding a bend like our throttle body elbows normally do it helped get rid of some of it. So by you moving your GM Maf that could have effected the direction of flowing air. All a hunch but it makes sense. That whistling you hear could just be the turbulence inside the manifold.