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MACE
Dodge Dakota
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1/25/2002
11:08:55
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 Subject: 4.7 70mm TB, Idle Fix
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I may have missed a post, but has there been any feedback on what causes the 70mm TB to get stuck at 1100 RPM idle, if there is a fix, and how that fix will be applied?
Pending these answers, I will have a stock 68mm TB with 2700 miles on it, for sale
And pending NYS Inspection with my Intense Performance 4 inch intake, I will also have the complete stock intake system for sale as well.
(may also sell parts of this, if the right offer comes along)
While I'm at it, also have the stock cat-back exhaust available, has about 1500 miles on it.
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alex
Dodge Dakota
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1/25/2002
13:32:06
| RE: 4.7 70mm TB, Idle Fix
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Here's the poop. Whenever you run the A/C or defroster, the A/C compressor kicks on, no matter. When the compressor kicks in at an idle, the engine feeds a little more fuel to the system to overcome the drag from the comressor and maintain a nice ~650 rpm idle.
Well, the Idle Air Control motor passage (where the Idle Air Control motor shoves the plunger in & out to control the idle) is a LITTLE bit too large. They're just made that way, and it is a mistake on the part of F&B. So, no matter what the idle air control motor does, the engine will rarely idle below about 900 rpm.
So, when the A/C kicks on, there's the little bit more fuel, and now the 900 rpm idle goes up to around 1100. Again, a manufacturing mistake, but for the horsepower gain that the 70mm version gave me, I will live with it.
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scat pack
Dodge Dakota
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1/25/2002
14:58:38
| RE: 4.7 70mm TB, Idle Fix
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Hey MACE (or anyone else with a 68 TB for sale) I'd love to replace my 65 with one of those 68's - let me know what you decide to do. I don't want to go too big as I tow a camper sometimes. garrick102@aol.com 2K 4.7 RC 4x4
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MACE
Dodge Dakota
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1/25/2002
16:03:37
| RE: 4.7 70mm TB, Idle Fix
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Message:
Alex, some interesting info...living in the NE, haven't run my A/C in awhile, but do run the defroster...gonna have to see that when I park after driving home from work, w/out the defroster on, if I gun it, does the idle still stick at 1100 RPM?
scat pack: I'll keep you in mind after I feel comfortable with the 70mm TB being reliable, I don't think this will be a issue though.
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alex
Dodge Dakota
JOIN HERE
1/25/2002
16:39:07
| RE: 4.7 70mm TB, Idle Fix
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I've noticed that once the motor warms up, that yeah, if I blip it, it will "hang" at 1100 or so, and eventually creep back down to about 900. Some days it will play nice and idle at 650 like the stock piece. Sometimes after a hard interstate run, when I get to the top of the ramp, it will stay at 1100 for a bit and then drop slowly.
The problem is that Bruce (at F&B) didn't have a 4.7L test truck while he was developing these TB's so there are some quirks that should've been worked out before he decided to charge $400. Like the idle, and the buzzy linkage that vibrates the gas pedal. But, I can live with them.
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scat pack
Dodge Dakota
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1/26/2002
09:11:05
| RE: 4.7 70mm TB, Idle Fix
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Thanks, Mace ! No rush, planning active suspension and rear shock change next.
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MACE
Dodge Dakota
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1/26/2002
23:59:38
| RE: 4.7 70mm TB, Idle Fix
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scat pack...me thinks you got more trail running in your blood than straight line times...where ya from, and have you done some cool off-roading?
(aka: hit the top of your head off the roof liner, negoiating some 'rough' spots in the road)
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scat pack
Dodge Dakota
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1/27/2002
08:25:33
| RE: 4.7 70mm TB, Idle Fix
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From the hills of western Mass - but I'm more of an acceleration junky. No clearance up front - plow frame - 700' driveway. Used to have fun rippng parts off my '75 W100 on the trails, but a lot of the ones I knew are gated off now. At 44, I'd rather take parts off with a wrench now. Getting away from motorcycles, hands get numb from vibration, so it's back to v-8 mopars- also have '69cuda & '72 Challenger project cars - think I'll sell Challenger to get more cash to throw at Cuda & truck. Good luck with that 70mm !
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BKBridges
Dodge Dakota
JOIN HERE
3/15/2002
19:15:06
|  RE: 4.7 70mm TB, Idle Fix
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Hey,
Havnt been here lately, but looks like I need to give an update and dispell a couple rumors!
4.7 throttle pedal vibration: Never noticed it on our 3 test trucks (2 2001 autos and one 2001 manual) The manual truck still has no vibration. He's running a 4" corrugated tube inlet system.
The vibes problem is caused by a standing wave set up in the intake tract. The stock elbow "box" that the 4.7 originally came with had a Helmholtz resonator cavity built into it to eliminate the problem. The way to fix it without using the box is to place a 1.5" wide by .050 thk piece of aluminum plate perpendiclar to the throttle plate at the outlet of the intake tract. This efectively divides the tract into 4 small "tubes" that will keep the standing wave from developing. This will work on stock TB trucks running aftermarket/ homebrew intakes as well. You will notice no vibration and a small increase in midrange power.
Erratic idle: We designed the TBS to provide a 400-1400 rpm range. You can verify this by placing a scanner on your truck and commanding the idle manually. F&B 70mm TBs idle well below 600 rpm. If you re-adjust your throttle plate your idle problem will not change. Dont do it!...
The idle problem is being caused by the PCM. We tracked it down on two trucks to the power steering pressure transducer. It was sending bad pressure signals to the PCM causing high idle when it should not. Once the adaptive cell for the idle was re-set the truck idled fine until the P/S pressure sensor acted up again...
The TB appears to make the problem MUCH more noticable due to its high "gain" on the idle circuit. We do not have a fix for it yet, but we reccommend getting a scan to run down what is commanding the idle high if you can. We will continue to delve into this until we KNOW whats up. If you are very dissatisfied we have always had a very easy return policy! I will post to more sites regarding our findings as we get them nailed down!
Bruce K Bridges
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CW
GenIII
3/15/2002
19:52:26
|  RE: 4.7 70mm TB, Idle Fix
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BKBridges:
Send me a 72mm TB and I will help track the problem down. I have acess to all the nessary tools, books and training.
2001 RC 4.7 5sp 9.25" 3.92 LSD
Ported 68mm TB, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" cold air, Roadmaster active suspention, Removed Third cat, Electric fan Convertion, HO cams.
Working on adjustable fuel pressure with return.
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CW
GenIII
3/15/2002
19:53:35
| RE: 4.7 70mm TB, Idle Fix
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Message:
Doh or is this only on 70mm TBs? If it is send me one of them.
2001 RC 4.7 5sp 9.25" 3.92 LSD
Ported 68mm TB, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" cold air, Roadmaster active suspention, Removed Third cat, Electric fan Convertion, HO cams.
Working on adjustable fuel pressure with return.
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BKBridges
Dodge Dakota
JOIN HERE
3/15/2002
20:11:39
| RE: 4.7 70mm TB, Idle Fix
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Message:
CW,
Thanks for the offer. Weve got the tools here too, just didnt have the OBDII module with me this afternoon...So far though high idle doesnt seem to be a big problem on the 72mm TBs...We need to get this understood...the software and hardware just get more inscruitable as the years go by...
Bruce K Bridges
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bernd
*GenIII*
3/16/2002
01:10:13
| RE: 4.7 70mm TB, Idle Fix
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Message:
Ain't it great how these PCM's work these days Bruce? (Ya have to admit, the old Mopar you got is much easier to tune.) ;)
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
14.55 @ 96.01mph
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CW
GenIII
3/16/2002
12:33:18
| RE: 4.7 70mm TB, Idle Fix
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Message:
Much prefer the drivability of the new ones:-)
2001 RC 4.7 5sp 9.25" 3.92 LSD
Ported 68mm TB, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" cold air, Roadmaster active suspention, Removed Third cat, Electric fan Convertion, HO cams.
Working on adjustable fuel pressure with return.
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MACE
Dodge Dakota
JOIN HERE
3/18/2002
10:45:48
| RE: 4.7 70mm TB, Idle Fix
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Message:
Bruce, thanks for the feedback and email.
Not considering a return at this point, glad to see the problem(s) are being looked at for a final fix and that a 'work around' has been offered.
Please update us when more information is available.
Thanks again.
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JoeC
Dodge Dakota
JOIN HERE
5/06/2002
00:54:48
|  RE: 4.7 70mm TB, Idle Fix
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Message:
What's the latest word on this problem?
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JoeC
Dodge Dakota
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5/06/2002
23:41:25
|  RE: 4.7 70mm TB, Idle Fix
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Message:
Well...
Has anyone confirmed what is causing the irractic idle?
Is it the power steering transducer or something else?
Has anyone with this TB had luck?
Bruce/Bernd? Anyone?
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BKBridges
Dodge Dakota
JOIN HERE
5/07/2002
12:07:38
| RE: 4.7 70mm TB, Idle Fix
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Message:
Hey!,
So far we have not gotten any closer to a "fix" for erratic idle. We have seen it reduce in magnitude after many drive cycles, but it still seems eccessively variant. We are very concerned and are searching for answeres. The PCM in 2000-2002 trucks appears to update very slowly, and requires many drive cycles to re-set the idle parameters.
The pedal vibration is set up by the motor itself (standing wave) and definitly goes away when the resonator cavity is placed back into the air intake. We are trying out heavier throttle blades (bronze material) in hopes that it will reduce the vibration felt by the driver, but inreality the wave will still be there unless the resonator cavity (of some sort) is used. The blade I mentioned in my earlier post does reduce the vibration and eliminates it on some trucks but its not as sure fire as we had hoped. We appreciate everyones patience in this and we are still working on understanding the problems better.
Thanks,
Bruce K Bridges
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alex
Dodge Dakota
JOIN HERE
5/07/2002
13:11:31
| RE: 4.7 70mm TB, Idle Fix
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I have had the 70 mm TB on my truck since late October and have been driving it daily (about 22,000 to 23,000 mi annually) since then. The idle used to hang up at 1100-1400 rpm at traffic lights and in regular low speed traffic. Only on certain random occasions would it idle below 900 rpm. Starting back in early April, it regularly idles between 400 & 700 (actually it fluctuates like everyone is describing) but I will take that any day over the 1100-1400 fluctuation!! I think you are right Bruce, it just takes however many run cycles before the PCM can handle it.
alex
PS- I'm still impressed with the power band every time I open it up.....
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R.L.Stuart
Dodge Dakota
JOIN HERE
5/07/2002
21:44:57
| RE: 4.7 70mm TB, Idle Fix
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Hello All
Good to hear from you Bruce,I had the Idle trouble with the 70mm and with the stock 68mm,Had the IAC replaced and the TPS replaced with the stock TB,I love my 70mmTB think it's the best Mod I have,My Idle trouble was from the Power Steering pump:Seems it was bad.It was replaced and some 4000 miles later my Idle is still perfect now I need new tires,Also when you remove the TB remove the o-ring gasket and drop it in a little hot water before you install it to get a good seal.
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JoeC
Dodge Dakota
JOIN HERE
5/08/2002
00:40:43
| RE: 4.7 70mm TB, Idle Fix
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Message:
Thanks for the response guys. I have put about 6000 miles on my 70mm TB and the hp improvement is worth the idle problem.
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w.henry
Dodge Dakota
JOIN HERE
7/30/2002
07:05:32
| RE: 4.7 70mm TB, Idle Fix
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I also have this same condition on a highly modified 5.9 ram with a hughes stage III throttle body. SO it is not just with your setup.
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