Need advice on loud shrill noise - LotusTalk - The Lotus Cars Community
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post #1 of 12 (permalink) Old 08-11-2019, 07:12 AM Thread Starter
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Need advice on loud shrill noise

This whine was always present since I've owned the car but never this loud and annoying. It started after my last track session earlier this spring. It is much louder in the cabin and you can barely hear yourself think. It does lower in tone and volume with more load on engine. Listen at the very end and as the engine is turned off it gives a cleaner audio of the sound. I move the camera around to see any pitch and volume changes and to show fuel pressure somewhat. TIA, Richard

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post #2 of 12 (permalink) Old 08-11-2019, 08:48 AM
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Looks like there has been some modification to the stock cooling and vacuum system. The noise could very well be coming from a vacuum leak.
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post #3 of 12 (permalink) Old 08-11-2019, 08:54 AM
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In the video I see a vacuum port that isn't covered (and a couple with some questionable vacuum caps on them) could it be a vacuum leak? I've also heard some say the throttle bodies on '06 and newer can make some noise. I did notice the fuel pressure regulator right near the noisy area, I've heard those make noises too, maybe try adjusting the pressure my 1/2 psi and see if that does anything. Just a few things to look at.

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post #4 of 12 (permalink) Old 08-11-2019, 08:59 AM Thread Starter
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Yes PO installed REV 300 on new Nikasil treated block and reworked new head. Mods leaned towards reliability rather than high hp. I did install CAI and headers along with new tune in Jan and the noise which has been there over a year started increasing after two track days and about 500 miles. I do need to put a brass plug in manifold where I disconnected a vacuum line and just plugged the line and wrapped in tape temporarily. I guess start spraying some starting fluid and see if I find any rpm increase when I get back home.
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post #5 of 12 (permalink) Old 08-11-2019, 09:04 AM Thread Starter
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Hi Jetblast where is the uncovered port that you see? In that one manifold there's a brass plug, vacuum line and then a clipped off vacuum line with solid plug that is taped until I can find another brass plug. Is there a port somewhere else that you are seeing?
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post #6 of 12 (permalink) Old 08-11-2019, 09:07 AM Thread Starter
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It does seem like much of the whine is around the fuel pressure regulator but in grabbing lines and reg and moving everything as much as I could I couldn't alter the sound.
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post #7 of 12 (permalink) Old 08-11-2019, 09:23 AM
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Quote:
Originally Posted by Catsailr27 View Post
Hi Jetblast where is the uncovered port that you see? In that one manifold there's a brass plug, vacuum line and then a clipped off vacuum line with solid plug that is taped until I can find another brass plug. Is there a port somewhere else that you are seeing?
I was referring to the port below the one that has the bolt stuck in the end of the hose, on the video at 0:26. Check the hose with the bolt too, those typically don't seal that well.

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post #8 of 12 (permalink) Old 08-11-2019, 09:24 AM
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It does seem like much of the whine is around the fuel pressure regulator but in grabbing lines and reg and moving everything as much as I could I couldn't alter the sound.
If it is the regulator, it's probably the diaphragm vibrating, that's why I suggested changing the psi a little bit, moving things around won't change it.

2005 Ardent Red Elise, Gut Sport wing & splitter, custom diffuser, Sector111: DSBrace, gPan3, subStuffy2, Larini Sport muffler, decat pipe, Schroth Racing 5 pts, wheel studs, Team Dynamics 1.2 with Hoosier A6s, Koldflash 200 ECU flash, BOE rear clam hinge, BC Racing single adjustables, Hawk pads, SS Brake Lines, HID lights, custom tail and high mount brake light...and much more...
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post #9 of 12 (permalink) Old 08-11-2019, 09:39 AM
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Do you have a surge tank with aux pump? That may be whining. Although like Jetblast I do suspect the FPR.

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post #10 of 12 (permalink) Old 08-11-2019, 09:40 AM
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Quote:
Originally Posted by Catsailr27 View Post
Yes PO installed REV 300 on new Nikasil treated block and reworked new head. Mods leaned towards reliability rather than high hp. I did install CAI and headers along with new tune in Jan and the noise which has been there over a year started increasing after two track days and about 500 miles. I do need to put a brass plug in manifold where I disconnected a vacuum line and just plugged the line and wrapped in tape temporarily. I guess start spraying some starting fluid and see if I find any rpm increase when I get back home.
Supercharged car? Spray a little water on the belt and see if it temporarily stops the noise. Plug all open vacuum ports. Aesthetically, a hose with a bolt in it just bugs me. But that's the coolant port for the TB, so that's not your problem.
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post #11 of 12 (permalink) Old 08-11-2019, 10:24 AM Thread Starter
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Yes Buzzard there is a surge tank and I have read about potential issues with that, Jetblast I'm going to try altering fuel psi when I get the car back home and I will plug any open port but was told those weren't an issue when I bought it. I agree that using a bolt to plug line could be sketchy so I will find proper sized caps and or plugs to seal visible ports. Pretty sure it's not the belt it's like an electrical part is vibrating loudly but am willing to spray some water on it to see if I hear any changes. When I get back home I have my stethoscope to listen some as well.
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post #12 of 12 (permalink) Old Today, 12:51 PM Thread Starter
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Hi me73,Jetblast, thebuzzard, Just want to update this post. I have put proper vacuum caps and or plugs in all the previously mentioned jury rigged plugging and a couple of other points to rule them out with vacuum leaks and problem continues. I noticed the tape covering port on FPR was gooey so I cleaned and resealed along with altering fuel pressure from 47 normal +-5lbs without any effect. Sprayed serpentine belt with water as suggest no change.

I ran my iphone around using db meter app and it seems the loudest between TB and FPR. This was a slight whistle when it first started months ago and has now turned into an ear piercing whine that would put any exhaust drone to shame. It does vary with engine load when on the hwy.

I tried the propane test with hose and ran it all over the intake area with no change. I have grabbed every hose and part moving, covering etc trying to see if I could alter pitch,volume and I can grab the DBW assy on the TB and cause some change.

A little background on the car it has REV300, surge tank, catch can, CAI, PPI headers and was raced for years by previous owner. I've had it a year and added new BOE tune, headers and CAI to the previous setup.

Just took another video and found by grabbing DBW TB I could alter the whine and I could feel vibration in the DBW. See link

Got back on LT and in searching I found this link https://www.lotustalk.com/forums/f25...lebody-374753/ and it indicated a broken intake manifold bolt. When I just went back out to check lo and behold the head of my bolt in same location was broken off and the bolt came out by finger. I'm keeping my fingers crossed and once I get a bold tomorrow i hope it takes care of my noise as I was reluctant to get it on the track sounding like that.

I hope it takes care of it and if it does thanks LT and Mobius97

Just talked with Andrew at BOE and mine being the early REV300 didn't have the ARP stud and bolt upgrade. I'm hoping the threads are ok and going to pick up a proper bolt for now and over the winter I'll do the upgrade. Richard
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