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Jimbo
GenIII
 
5/06/2002
14:15:29
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 Subject: 4.7 plenum resonance?
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I've seen a bunch of posts recently about resonance in the 4.7 plenum when you remove the factory airbox. I had a K&N cone filter attached to the end of the airbox but removed the airbox a few weeks ago and did a homebrew PVC air intake. I haven't heard this resonance, but maybe I'm just missing it. Need to know what to look/listen for and what the consequences are. Bruce says to put a piece of aluminum perpendicular to the throttle blade (on the performance board). Any other input on this?
'01 CC SLT 2WD 4.7 5-Speed 3.55 LSD
K&N homebrew, TPS @ .74, Autolite 3923s, Rhino Liner, Checkmate FX Tonneau
Sony CDX-C8050X, PPI 430iqx, JL 10W-4
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Clevite 77
Dodge Dakota
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5/06/2002
14:33:12
|  RE: 4.7 plenum resonance?
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I have an 2002 so everything should be identical, is this the h-brew you did? mine is quite loud (I like it though)
Pics of my h-brew
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bernd
*GenIII*
5/06/2002
15:12:58
| RE: 4.7 plenum resonance?
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The wonderful thing about it is that not all have this vibration.
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
14.55 @ 96.01mph
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D
Dodge Dakota
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5/06/2002
16:46:22
| RE: 4.7 plenum resonance?
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how can you tell if you do have vibration?
mine is just freakin loud, it vibrates everything
in the cab...
D
01/4.7/CC/airaid+3"homebrewed/180stat/jet2
DynomaxRaceWeldedMuffler+3"catback/TB
spacer/ported-polished68mmTB/no clutch fan
DJMdrop3-6
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Duner
Dodge Dakota
JOIN HERE
5/06/2002
17:25:35
|  No Biggie!
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Depending upon the severity of the resonance - you can feel it in the gas pedal under your foot.
Mine does it, but since I know what it is and understand why it does it and the mere fact that it isn't hurting anything..... I just ignore it.
Bernd - the trucks that don't have the resonance: do they still have the short vertical stub hanging down from the top of the intake manifold right behind the TB?
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bernd
*GenIII*
5/06/2002
18:00:02
| RE: 4.7 plenum resonance?
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Duner...didn't look but will check the pictures from the install later on this evening. How's your vibration at 72-75mph?
Here's what I found so far:
2000 4.7L - One large resonance chamber on the airhat
2001 4.7L - One large resonance chamber but late model 2001's have dual chambers
2002 4.7L - Dual (one large and one small) resonance chamber (Hmmm...wonder what they changed)
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
14.55 @ 96.01mph
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Duner
Dodge Dakota
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5/06/2002
18:12:18
| Only at tip-in.
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I don't have any resonance vibration at 72-75 mph. I only feel the vibration at tip-in when I'm just easing into the throttle.
DC probably needed to go to the dual resonance chambers when they increased their TB bores from 65mm to 68mm. They may have received some feedback from the early 2001 drivers about the resonance?
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mills
GenIII
5/06/2002
18:38:30
| RE: 4.7 plenum resonance?
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i have a 2k dak with a 360 intake....i havent felt/heard any of this resonance....it just made the intake louder....interesting
burn dust.....eat my rubber!!! - Clark W. Griswold
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alex
Dodge Dakota
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5/06/2002
19:13:18
| RE: 4.7 plenum resonance?
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I installed my 70mmTB after dark and never noticed the lil plastic blade in the mouth of the intake manifold, so I guess mine's still there. I really only feel the vibration in the pedal at about 75-80 when I am right at tip-in. Slight grades, etc. When I let off slightly, it goes away, when I accelerate any more it goes away. It don't really bother me since I live in the Piedmont (atlanta) and it's hard to hold one single throttle position out on the highway. So the vibration usually coems & goes.... whatever.
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Dan Gruber
GenIII
5/06/2002
20:23:20
| RE: 4.7 plenum resonance?
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Bernd,
Hate to throw a wrench in your findings...I've got a 2000 4.7 (CA version) with 2 chambers in the airhat. One large one on the outside of the main air tube bend, and a small one on the inside.
But it doesn't matter...I'm keeping it on a shelf until I have to do a visual check & smog inspection in 2004. I've got a Z tube with the air filter canister. And no vibration, just more noise, especially when I had my home-brew on there.
Say it with Krylon!
Dan
2000 CC SLT 4.7 4X4 Auto 3.55 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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bernd
*GenIII*
5/06/2002
21:26:39
| RE: 4.7 plenum resonance?
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That is wierd. Bruce (Flometrics) has an airhat from a 2000 4.7L and it's only got one chamber. (Dodge....Different.) ;)
Duner, I checked on one of the pictures we took. Yup, that little piece is there as well.
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
14.55 @ 96.01mph
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Duner
Dodge Dakota
JOIN HERE
5/06/2002
22:45:29
| Mine is a single as well.
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Hmmmm, I took that piece out on mine and figured it was there to suppress the resonance. I wonder if removing that small piece helps or hurts the resonance issue? I viewed it as an obstruction that hindered airflow and it disappeared quite quickly. hehehe
I dug out my old airhat and it has a single chamber as well ('00).
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CW
GenIII
5/06/2002
23:02:16
| RE: 4.7 plenum resonance?
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This is what my 2001 came with for a air hat.
Obviously mine is eliminated and with the stock TB no resonanse. Maybe it has to do with the thinner throttle blades of the performance throttle bodys.
2001 4.7 RC 5sp 3.92 LSD
Click on thumbnail for mods.
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JoeC
Dodge Dakota
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5/06/2002
23:48:22
| RE: 4.7 plenum resonance?
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Thinner Blade on 70 mm, and it is plastic, not brass.
What about the idle problem on this TB??
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Jimbo
GenIII
5/07/2002
07:55:18
| RE: 4.7 plenum resonance?
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From what you guys are saying it sounds like this is just a noise/vibration issue and won't hurt anything. Which is fine with me since I like the loud deep sucking sound.......hmmmm I won't go there.
C-77 My h-brew looks the same except I used a bigger filter with a sleeve so I didn't need the flange. The only problem was having to relocate my cruise control servo. But after a little hacking and bending that problem was solved.
Dan G - you still looking to go down to Bradenton? My e-mail has been down so I haven't had a chance to look you up. Next few weeks look bad but towards the end of the month maybe we can get together....
'01 CC SLT 2WD 4.7 5-Speed 3.55 LSD
K&N homebrew, TPS @ .74, Autolite 3923s, Rhino Liner, Checkmate FX Tonneau
Sony CDX-C8050X, PPI 430iqx, JL 10W-4
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bernd
*GenIII*
5/07/2002
17:48:09
| RE: 4.7 plenum resonance?
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Joe: The throttel blade is not plastic on the 70mm (or 72mm). The idle problem is directly related to the (very slow) adaptive idle (PCM). There's also a problem with some of the Power Steering Pressure Transducers causing poor idle quality (erratic).
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
14.55 @ 96.01mph
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JoeC
Dodge Dakota
JOIN HERE
5/08/2002
00:53:22
| RE: 4.7 plenum resonance?
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It looks plastic (maybe some kind of composite??). Not brass/bronze like stock.
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bernd
*GenIII*
5/08/2002
11:04:22
| RE: 4.7 plenum resonance?
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Message:
They're anodized.
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
14.55 @ 96.01mph
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