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Fuel.rails and injectors generate significant underhood noise
The 4 rear fuel injectors received foam covers while the front 4 did not....
Toyota discontinued the foam covers, however plenty available from donor vehicles.
These OEM foam covers do little to isolate the.injectors cacophonious clicking.
Injector pulsations can be felt in the fuel rail, suggesting the application of noise and vibration treatment there would make a difference.
Am considering fuel.resistant silicone tubing trimmed and slit to cover the fuel.rail.
Welcome suggestions on alternative solutions.
Fuel rail from 1999 LS400. Clearing mounting ears requires slitting if using tubing cover. Perhaps heat shrink tubing over EPDM foam presents an option.
Do you reccomend a free sound meter app for Android?
I recommend this and the video which shows the actual measurement. So that we also can hear the sound and compare actual difference of the sound and it's level. Experiments need to show the data, you know.
The fuel injectors, fuel rails and pulsation dampers generate a fair amount of noise.
LS400's employ fuel pulsation dampers on each fuel rail.
Both fuel pulsation dampers on 1999 LS400 are near the firewall and radiate a fair amount of noise, so decided to start there.
Toyota did not address this so am doing so now.
The best way to contain noise is closest to the source as possible.
Investigation revealed that Honda/Acura employed a snap fit pulsation damper cover that fits perfectly over our Denso units.
With assistance of Parts department at McGrath Acura was able to come up with part number
16681-PRB-A00. $6 each.
Using a rubber hose as before and after istening device, verified these plastic covers help contain pulsation damper noise.
Anyone wishing before and after sound meter data is welcome to purchase these inexpensive parts and post readings.
1999 LS400 pulsation damper..A majority of noise is emitted from the top center screw button area
Pulsation damper cover installed. Perfect snap fit.
Honda part number Backside of the cover depicts a track that allows the pulsation damper to breathe. I believe the Honda damper is installed on a horizontal plane so it incorporates a drain tube. Since our dampers are mounted vertically, I elected to use silicone sealer to close this hole to better contain the noise. Probably another P.N. available without this drain hole. A screenshot of fuel pulsation damper with cover.....and without drain hole. Oftentimes the cover is sold only as an assembly with the pulsation damper. Please post part number should you should come across one without drain hole Rubber hose served as listening device
Reduce NVH (noise, vibration and harshness) in one place, it becomes more apparent elsewhere.
Fuel injector/rail noise is pronounced on our LS400 and have been researching options for dampers and barriers
Had a look at how Porsche dealt with fuel injector rail noise and several images of plastic(?).fuel rail covers with foam inserts and another version with foam covers that wrap around the entire fuel rail with separate covers.
Another version of fuel rail cover where foam insert is inside cover, but does wrap around the fuel rail. Underside of Porsche fuel rail cover.
Best practice is to dampen and contain the noise closer to the source than attempting to contain it in the expanse of an engine compartment. Our engine cover is a barrier to sound, but does not effectively contain fuel injector noise.
Do you reccomend a free sound meter app for Android?
Buy a professional sound meter, I can recommend the one I use when I'm adjusting my audiophile system and messing around with different subsonic loads for my guns
04-26-19, 05:36 PM
Noisy fuel rails and injectors
