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Catfish Craig
Dodge Dakota
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4/08/2006
22:45:04
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 Subject: 4.7 Acceleration Problems
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Anybody had this trouble with their 4.7. Under hard acceleration, pretty regular with my 4.56s, it feels like the truck goes flat. Oddly I didn’t notice this with the 3.55s. What I mean is the truck feels like it just won’t go anymore like not getting any gas or out of “get up and go”. It usually happens around 3500. I just push the accelerator more. No codes, not missing or hesitating. Just won’t go is the best description I can come up with. Currently my SC is in performance mode running 93 Octane. New Plugs and Air filter cleaned 3K ago, any Ideas?
2002 QC 4.7 AWD FIPK 4.56 SuperChips 3” BL 285/75/16 Mud Rovers
CC
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DanK
Dodge Dakota
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4/09/2006
10:24:37
|  RE: 4.7 Acceleration Problems
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Your tourque curve peaks at about 3600rpm. With the 4.56 gears, it doesn't take long to get there, and that peak will now occur at a lower speed in each gear, relative to the 3.55 gears.
Looky here - Same engine, different vehicle.
http://www.wjjeeps.com/misc/curve_47.jpg
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caulk
Dodge Dakota
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4/09/2006
15:54:51
| RE: 4.7 Acceleration Problems
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Don't have an explanation for ya, but...
I'll drive to your house and swap you axles! :) I've got 3.55's if you want them back
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GraphiteDak
GenIII
4/09/2006
22:47:07
| RE: 4.7 Acceleration Problems
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I don't have any flat spot. And no difference is I floor it to 6k+ or if I hold the gears manually and give it half throttle. It pulls pretty even either way right up to 6K+
Make sure you don't have a bad TPS or something silly.
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Catfish Craig
Dodge Dakota
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4/10/2006
21:29:48
| RE: 4.7 Acceleration Problems
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I was thinking maybe a TPS. I'll test it this weekend and clean the TB also.
Thanks CC
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Ron
Dodge Dakota
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4/18/2006
19:10:53
| performance issues...
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Ok...so I couldn't leave well enough alone.
I have a ...
2000 4.7 liter,5 spd. 3:93 gears Quad Cab 4x4
I have done the following:
32" bf/goodrich
Electric fans(removed the clutch fan)
Full Duel Exhaust:
Gibson headers
Hi-flow Cats
Duel Flowmasters 40 series
Airraid cold induction with throttlebody spacer
Superchips programmer(set to performance)
The truck ran great, but of course you always want more...
so I added the BBK 70mm throttlebody.
Here is my dilema it boggs down any time under 3000RPM and seem to have lost all of it's low end torque.
Is this too much "flow" for the 4.7l?
Are heads and a cam the only answer?
any assistance would be appreciated...
~Ron
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mopardr39
Dodge Dakota
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4/24/2006
23:49:39
| RE: 4.7 Acceleration Problems
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Has anyone recalibrated there computer for the bigger tires and different gears???? I think your computers are not sure what is going on and are blind to the fact...They are in control and need to know...shift points...fuel control...tcc engauge...ect...How can you be in charge and do not know who or what you are commanding?????It just won't work.
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GraphiteDak
GenIII
4/25/2006
01:45:22
| RE: 4.7 Acceleration Problems
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I believe that the computer uses the speed sensors INSIDE the transmission for all of that. So changing gears, tires has no effect.
Changing gears don't even throw off your speedo at all. Only changing tires does that.
I have a 68MM TB that I removed a LOT of material from...
And there's a sample of the metal shavings I swept up!
Mine didn't lose anything at all. Maybe I'd look for the TPS being way off or something.
Also, I threw on HUGE duals with 2 1/2" from the manifold back.
That didn't even take away any tire ripping bottom end.
Even though many will say it would :)
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Catfish Craig
Dodge Dakota
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4/25/2006
22:03:22
| RE: 4.7 Acceleration Problems
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Well I adjusted the TPS. Before messing with it, I read about .593 So i took a rat file to the brads and it is reading dead on .7 Also checked WOT it reads 3.83 and the book says it should be 4.5. So I’m wondering if this is the trouble??? The off line is better. Can someone with a 4.7 let me know what they read at WOT.
Thanks CC
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Mr.Sleepy
Dodge Dakota
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4/26/2006
21:03:49
| RE: 4.7 Acceleration Problems
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Computer can't automatically calibrate for bigger tires. The computer also can't adjust shift points without a reprogram. Your tire shop should have done this for you, and any axle shop can do the reprogram. Call around, never hurts.
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GraphiteDak
GenIII
4/28/2006
20:33:45
| RE: 4.7 Acceleration Problems
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HUH???
I did a DRASTIC gear swap. My auto STILL shifts at 5500 on it's own. So I am not sure what you are getting at or why it would NEED to adjust. Never needed to adjust the speedo either as it reads off of the speed of the axle AFTER the gears.
Craig. If someone don't chime in, maybe later I'll go take a reading of the TPS at wide open.
I would THINK it would be near 5.0 Volts as that is the upper end of the voltage the POT would see int he TPS.
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