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Unread 01-21-2013, 03:05 PM   #1
caiati
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Please tell me I'm not crazy!

Hey guys... First of all let me start by saying that I've had my WK since June and I haven't even put 5,000 miles on it. I have a company vehicle so fortunately my personal vehicle only gets used on the weekends. I meet one of my co-workers every morning at a halfway point so he doesn't have to waste gas money. I always take his vehicle home and give him the company truck to help compensate for gas. With that said, he has a 2001 WJ with the 4.7. It is NOT an H.O. motor but it seems like it has more power than mine. He has 178,000 miles on his and has had it for over 10 years. Still the original motor. He put a flowmaster muffler on it and a K&N CAI years ago. He also did a teraflex 2" coil over lift with 265's. I did a RC 2" lift with 265's. Virtually its the same drivetrain besides the transmission. The only thing he has different is the CAI. I can't see the CAI making that much improvement. My problem is that my transmission is constantly searching through gears. It seems like I have to make it downshift to have sufficient power. I know it's a different transmission with somewhat of a "seamless" shift, but it is quite aggravating. I'm not a teenager looking to drag race by any means but it is quite depressing when my 2006 seems like it has less power than the 2001. My question is this: What can I do to see an increase in power/throttle response and a more responsive transmission?

Will spark plugs make any difference? I know about doing the tuner etc... but my goal isn't to have MORE power than his, but figure out why mine seems to have less power. What about flashing the PCM? Any suggestions?

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Unread 01-21-2013, 03:15 PM   #2
JeepN4KC
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You need a tuner to recalibrate for the bigger tires.
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Unread 01-21-2013, 03:32 PM   #3
caiati
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That's it? I'm not doubting that a tuner will help but I know that the 2001 wasn't tuned at all so why would it feel like it has more power? His 2001 has the same size tires as mine. What tuner do you suggest?........ Also, when I have it in tow/haul mode, it seems to react much better and the tranny doesn't feel as mushy...
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Unread 01-21-2013, 03:55 PM   #4
caiati
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Instead of buying a tuner, can I have the dealership reprogram for bigger tires?
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Unread 01-21-2013, 04:03 PM   #5
trax95008
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Quote:
Originally Posted by JeepN4KC
You need a tuner to recalibrate for the bigger tires.
This does not address the OP's issue. Recalibrating for larger tires will not gain you more power. I'm pretty sure a dealer will NOT recalibrate for larger tires for you. Have you compared the weight of the two vehicles? Your WK may be a little heavier than the WJ
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Unread 01-21-2013, 04:09 PM   #6
sk1er18
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The WK is heavier and has a lot more "nannies" due to the new computer controlled systems (throttle by wire). So although the engines/trans/gearing specs are very similar, the reduction in performance due to larger tires is more noticeable on the newer vehicles.
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Unread 01-21-2013, 04:15 PM   #7
caiati
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Quote:
Originally Posted by sk1er18
The WK is heavier and has a lot more "nannies" due to the new computer controlled systems (throttle by wire). So although the engines/trans/gearing specs are very similar, the reduction in performance due to larger tires is more noticeable on the newer vehicles.
That makes perfect sense. I guess I have to drop $300 on a tuner, although from what I've read there hasn't been any true power gains.
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Unread 01-21-2013, 04:22 PM   #8
sk1er18
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Getting the shifting back to normal, correcting the speedometer, reading DTCs and turning off the annoying TPMS warning chime for airing down offroad are worth the $300 (flashpaq)... any minimal power gains are sort of an "added bonus" IMO.
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Unread 01-21-2013, 04:31 PM   #9
caiati
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Quote:
Originally Posted by sk1er18
Getting the shifting back to normal, correcting the speedometer, reading DTCs and turning off the annoying TPMS warning chime for airing down offroad are worth the $300 (flashpaq)... any minimal power gains are sort of an "added bonus" IMO.
I'm assuming we are talking about the superchips 3875 flashpaq. If so, which tune on the flashpaq do you recommend? Meaning what octane etc...
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Unread 01-21-2013, 04:40 PM   #10
sk1er18
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I did quite an extensive test with the different tunes and honestly found that my engine ran the best with the stock tune modified for tire size. Keep in mind that I have the Hemi that is already tuned from the factory for 89 octane. With the 91 octane performance tune the engine actually felt less responsive and I got worse gas mileage.

I'd do the same with the 4.7L.... try the stock tune modified for the tire size to give you a "baseline". Try to use the same gas station consistently and see how your performance/efficiency are for a good month or two, then step up to the 87 performance tune and see if anything changes, then repeat with the 91 performance tune. See what works best and then stick with it.
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Unread 01-21-2013, 04:42 PM   #11
caiati
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Will do. Thanks for the advice. It may be a little while before I can actually buy the tuner but ill get there.
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Unread 01-21-2013, 05:41 PM   #12
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Quote:
Originally Posted by trax95008 View Post
This does not address the OP's issue. Recalibrating for larger tires will not gain you more power. I'm pretty sure a dealer will NOT recalibrate for larger tires for you. Have you compared the weight of the two vehicles? Your WK may be a little heavier than the WJ
Really? I believe he stated:

Quote:
Originally Posted by caiati View Post
My problem is that my transmission is constantly searching through gears. It seems like I have to make it downshift to have sufficient power.

I didn't say the tuner would give him more power. It would reset the tire size so his speedo/odo/trip were calibrated right and his tranny would know what is supposed to be happening. His tranny is shifty because the Jeep thinks it has stock sized tires that are rotating slower.
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My Build Thread WK
My Other Build Thread XJ
'01 XJ with some stuff
Sept 2013 Cherokee of the Month
'07 WK with some other stuff
~RED WK CLUB #7~
'11 KK with mostly stock stuff
'06WK our first Jeep with stock stuff - totalled and gone
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Unread 01-21-2013, 10:55 PM   #13
trax95008
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I guess that's possible, however I went from the factory 29" tires to 32" tires for about 3 weeks before I had a chance to recalibrate and my tranny acted perfectly normal
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Unread 01-22-2013, 08:29 AM   #14
Pac Man
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You need to recalibrate for your tires.

The real issue is your jeep is 700-800 pounds heavier than his... So it will feel like you have 70-80 LESS horsepower than he does.
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Unread 01-22-2013, 06:22 PM   #15
caiati
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Quote:
Originally Posted by trax95008
I guess that's possible, however I went from the factory 29" tires to 32" tires for about 3 weeks before I had a chance to recalibrate and my tranny acted perfectly normal
Do you have the 4.7? Don't get me wrong, it doesn't feel totally gutless but I live in a very hilly/mountain environment so I have to make it downshift for the power needed to climb the hills.
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