Hissing/rattle from 3.5-4k RPM after OFT

[steve99]

Originally Posted by Griever423

Checked last night and it is the UEL stg 2 tune. Running the Grimmspeed intake so no sound tube. The noise is definitely metallic in sound. There is some hissing noise too but normal for an aftermarket header from what I can tell. The metallic rasp is what bothers me. It's pretty loud. It's noticeable upon acceleration but VERY noticeable upon decel.

metalic rattle on decel sound mechanical ie exhaust hitting on something

[Interflop]

I'm glad this is normal. I also experienced this after flashing the Stage 1 OFT tune to my BRZ and was hoping this new sound wasn't something wrong.

[kch]

Originally Posted by Interflop

I'm glad this is normal. I also experienced this after flashing the Stage 1 OFT tune to my BRZ and was hoping this new sound wasn't something wrong.

Well there's some dispute and no one can actually explain what (specifically) is causing the noise. Everyone seems to just be ok with the "it's the variable valve timing, bro" explanation, but I've never seen anything more specific than that.

[dratom]

Originally Posted by steve99

metalic rattle on decel sound mechanical ie exhaust hitting on something

I just fitted up a PSR + over pipe and flashed the OTS Stage 2 UEL e85. I have the exact same symptom.

The vibration is hideous, in that very narrow band around 4K. Obviously the alignment of something changed in the removal and refitting. I wonder if it's related to the mid pipe hanger, it seems to be coming from right under my seat (RH drive). I undid that at the pipe end to get the over pipe out.

Has anyone hunted down what this was? I'm not really looking forward to getting back under the car and looking for it.

[illmatic_frs]

For me the sound changed over time and after about a week it was clearly the VVT. It actually became harmonious and pleasing to the ear lol.

However your description is more a vibration and not a sound onlu, so I'd say it's probably not from the VVT

Sent from my HTC One M9 using Tapatalk

[steve99]

Originally Posted by dratom

I just fitted up a PSR + over pipe and flashed the OTS Stage 2 UEL e85. I have the exact same symptom.

The vibration is hideous, in that very narrow band around 4K. Obviously the alignment of something changed in the removal and refitting. I wonder if it's related to the mid pipe hanger, it seems to be coming from right under my seat (RH drive). I undid that at the pipe end to get the over pipe out.

Has anyone hunted down what this was? I'm not really looking forward to getting back under the car and looking for it.

sounds like overpipe on the front sway bar mount.

try this,

undo the midpipe hangar bolt completly, move the bracket with hole in it aboce the bolt hole and replace bolt so bracket is now above bolt, this will loft mid pipe and overpipe slightly. Put large washer on bolt and tichten with bracket still above bolt.

see if that helps

[Wayno]

Originally Posted by dratom

I just fitted up a PSR + over pipe and flashed the OTS Stage 2 UEL e85. I have the exact same symptom.

The vibration is hideous, in that very narrow band around 4K. Obviously the alignment of something changed in the removal and refitting. I wonder if it's related to the mid pipe hanger, it seems to be coming from right under my seat (RH drive). I undid that at the pipe end to get the over pipe out.

Has anyone hunted down what this was? I'm not really looking forward to getting back under the car and looking for it.

Did you get new ones with the slip joints above the tubes or second hand ones that are below? If they're the old ones it will rub at exactly 4k.

[tracerit]

Is it advisable to try to remove this noise from the Stage 2 EL E85 tunes? I installed a Perrin CAI and ran the stock tune. The intake sound is absolutely awesome.

Then I installed the Stage 1 EL 91 tune, the 4k rasp just completely overshadowed the CAI noise... I can only hear it at 3000-3500rpm, then from 3500-4000 it's just a high shrieking noise lol.

Went to the Stage 2 EL E85 tune and absolutely love the smoothness of the car now. Absolutely wonderful.... until 3500rpm again.

Ideally I'd love to be able to run E85 and NOT have the rasp. I can live with the torque dip.

[dratom]

@Wayno @steve99 thanks guys. I do have the slip joint on the bottom - so looks like the way I can choose between the two scenarios would be to remove the alloy tray and take it for a drive. Does anyone know if the rear fibrous tray is secure without the alloy tray - or should I remove that before driving as well?

Assuming it's the slip joint is there something I can put between the tray and pipe that will survive heat and abrasion or am I taking a dremel tool to the plate to make a new window?

[steve99]

Originally Posted by dratom

@Wayno @steve99 thanks guys. I do have the slip joint on the bottom - so looks like the way I can choose between the two scenarios would be to remove the alloy tray and take it for a drive. Does anyone know if the rear fibrous tray is secure without the alloy tray - or should I remove that before driving as well?

Assuming it's the slip joint is there something I can put between the tray and pipe that will survive heat and abrasion or am I taking a dremel tool to the plate to make a new window?

you might just be able to just dent the tray. look for the rub mark and put a dent in that area

[travisb]

The heat shields on my o2 sensors rattled because the sensors were not seated all the way. Always rattled around 3500 rpm. I could watch them spin while someone else revved the car.

[Wayno]

Originally Posted by steve99

you might just be able to just dent the tray. look for the rub mark and put a dent in that area

Exactly. Use a hammer. The metal isn't that hard. Don't drive without the skid plate

[steve99]

Originally Posted by travisb

The heat shields on my o2 sensors rattled because the sensors were not seated all the way. Always rattled around 3500 rpm. I could watch them spin while someone else revved the car.

This means sensors not screwed in all the way, this can cause incorrect reading as sensor tip not in exhaust flow or leaks.


Best to remove sensors, run a M18 by 1.5mm pitch thread tap/chaser through 02 bungs in header then sensors will seat properly

[dratom]

Originally Posted by steve99

you might just be able to just dent the tray. look for the rub mark and put a dent in that area

Originally Posted by Wayno

Exactly. Use a hammer. The metal isn't that hard. Don't drive without the skid plate

Well, I found the culprit. It was indeed the rear slip joint touching an inopportune bulge on the skid plate.

Not any more.