Need help after cat-back install - JKowners.com : Jeep Wrangler JK Forum
 
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post #1 of 12 Old 02-14-2012, 01:39 PM Thread Starter
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Question Need help after cat-back install

Well a couple of months ago, I installed an AFE cat-back exhaust. Main reason was to hopefully free up a bit of horse power and get a bit better departure clearance from stock exhaust. I understand that going to a larger diameter (went from 2 1/2 to 3") exhaust can potentially decrease torque a bit, but figured the difference would be negliglbe. So far, the jeep seems to want to down shift a little too eagerly. This results in it being under powered during normal cruising and as a result wants to hunt for gears a bit. As an example, when cruising along at 45 mph, it use to stay around 1800 rpm and pulled just fine. Now it downshifts to about 1400-1500 rpm, and feels like it's starting to bog. If I get on the gas slightly I can feel it trying to figure out which gear to pick since it can't pull anymore. Obviously, if I get on it harder (keep your comments to yourselves), it will downshift but nearly immediately tries to drop back into a higher gear. Also, when installing the cat-back, we had to relocate the vapor canister. It had been moved before when the skid plate was put in, and installed at about a 45 degree angle lengthwise. This time, we attached it flat to the tub just above rear axle (it is in no way close to axle). Now, for whatever reason, I keep getting "gascap" spelled out on the odometer, and the gas cap is exactly where it's supposed to be and fits just fine. Any ideas on either of these problems?

Last edited by Flux; 02-14-2012 at 01:42 PM.
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post #2 of 12 Old 02-14-2012, 02:06 PM
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people who change out their stock components expecting to see any power from these engines are dumb.

re hook up the evap caniser.


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post #3 of 12 Old 02-15-2012, 05:25 PM Thread Starter
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As I mentioned, I didn't expect any major increase in horsepower. If I got 8-10 out of it, I'd be lucky. Primary concern was increased ground clearance. Also, when I decide to add on supercharger, the benefits will be realized. I never said I disconnected my evap canister, I placed it back to the correct position from the angled one it had been at. Did you even read the post there Sparky?
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post #4 of 12 Old 02-15-2012, 07:06 PM
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My trans. dose the same thing , 45 to 50 it locks and unlocks the torkconverter sometimes it flutters before it shifts. shifted A lot before, the flowmaster made it stand out. jeep said if no code its fine, I don't like it... its stock other than that . I think your gas cap thing is a leak in the evap lines ,
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post #5 of 12 Old 02-15-2012, 07:43 PM
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Skip the exhausts/intakes/etc. and go straight for the gears.

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post #6 of 12 Old 02-15-2012, 08:48 PM Thread Starter
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I'm running 5.38s. Pulled just fine prior to cat-back. Still pulls when I'm on it. Just struggles during cruising. I guess I should mention I'm driving Slippery's old jeep. 40's, 60's and of course the 5.38s.

Last edited by Flux; 02-15-2012 at 08:50 PM.
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post #7 of 12 Old 02-15-2012, 09:04 PM
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Your gas cap code could be the gasket on your evap. It is thin, green, and sits under the white plastic gizmo. Or one of your lines may be kinked or loose. Sorry for the high tech terms....

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  1. Cleghorn tailpipe mod
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  3. Heartbreak Ridge bumper scuffs
  4. Goler gas tank skid mod
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  6. Woods evap cannister relocate (Wow, an intentional mod!)
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  8. Calico fender realignment and texturing
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post #8 of 12 Old 02-15-2012, 09:30 PM Thread Starter
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RiggerMike, thank you for the input. I must say, you technical descriptions leave nothing to the imagination. I salute you, Sir!
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post #9 of 12 Old 02-16-2012, 11:57 PM
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people who change out their stock components expecting to see any power from these engines are dumb.
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post #10 of 12 Old 02-17-2012, 11:03 PM
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Quote:
Originally Posted by cloud View Post
people who change out their stock components expecting to see any power from these engines are dumb.
x2


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post #11 of 12 Old 02-18-2012, 09:24 AM
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any one have an idea why the trans shifts like that , any one except the two snot nose booger eaters ,your not helping
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post #12 of 12 Old 02-19-2012, 03:00 PM Thread Starter
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Akabonz, thank you for the assistance.
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