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Author Topic: Drivability issue  (Read 4010 times)

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Offline Trainman638

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Drivability issue
« on: May 21, 2010, 04:39:45 PM »
I'm having issues with my Mule (95YJ 2.5 125,000 miles). It starts and runs fine until it gets warmed-up then it feels like it's missing. An intermittent miss? Is that even possible? I've recently added elec. cooling fan, 170amp Alt, 19lb injectors, removed air box restriction, 4.0 TB, Accel coil and wires and new plugs gapped to .060. Since it still has the factory exhaust, I was thinking maybe the cat? Any help would be greatly appreciated.   :puzzled:
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95 YJ 2.5/ax5/np231. 4" superlift, 33" MT's, 4.0tb, 136amp alt, 19lb injectors, electric fan, smittybilt 8k winch, custom bumpers and rock sliders, rhino'd tub, header and ceramic coated exhaust.
67 M416 trailer painted to match.
96 XJ 4.0/ax15 My wife's Jeep and my new project.

Offline jfrabat

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Re: Drivability issue
« Reply #1 on: May 21, 2010, 05:04:02 PM »
Quote from: Trainman638 on May 21, 2010, 04:39:45 PM
I'm having issues with my Mule (95YJ 2.5 125,000 miles). It starts and runs fine until it gets warmed-up then it feels like it's missing. An intermittent miss? Is that even possible? I've recently added elec. cooling fan, 170amp Alt, 19lb injectors, removed air box restriction, 4.0 TB, Accel coil and wires and new plugs gapped to .060. Since it still has the factory exhaust, I was thinking maybe the cat? Any help would be greatly appreciated.   :puzzled:

Could be the cat, but I am wondering if the Accel coil can handle the .060" gap as well...  I used to have that one, and I dont remember it handling such a gap.
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'94 YJ 2.5L with 4" RE lift, Superwinch EPi9.0, FoMoCo e-Fan, SD30 and SD35 w/ARB-5.13, 165A alt., 33" BFG KM2 on 15" AR wheels, Sony sound system, Pavement Ends Hardtop, Hydroboost

Offline Trainman638

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Re: Drivability issue
« Reply #2 on: May 21, 2010, 05:19:00 PM »
If the coil could'nt handle the gap, would'nt I have had this problem since I installed it? Or on start-up?
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95 YJ 2.5/ax5/np231. 4" superlift, 33" MT's, 4.0tb, 136amp alt, 19lb injectors, electric fan, smittybilt 8k winch, custom bumpers and rock sliders, rhino'd tub, header and ceramic coated exhaust.
67 M416 trailer painted to match.
96 XJ 4.0/ax15 My wife's Jeep and my new project.

Offline sharpxmen

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Re: Drivability issue
« Reply #3 on: May 21, 2010, 05:23:25 PM »
Quote from: Trainman638 on May 21, 2010, 05:19:00 PM
If the coil could'nt handle the gap, would'nt I have had this problem since I installed it? Or on start-up?

why would you gap to .060 with stock ignition? - yes, that can be a problem (not saying that is the case but use stock gap instead to eliminate the possibility)
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'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

Offline Trainman638

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Re: Drivability issue
« Reply #4 on: May 21, 2010, 05:27:52 PM »
It's a 40,000 volt coil.
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95 YJ 2.5/ax5/np231. 4" superlift, 33" MT's, 4.0tb, 136amp alt, 19lb injectors, electric fan, smittybilt 8k winch, custom bumpers and rock sliders, rhino'd tub, header and ceramic coated exhaust.
67 M416 trailer painted to match.
96 XJ 4.0/ax15 My wife's Jeep and my new project.

Offline Jeffy

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Re: Drivability issue
« Reply #5 on: May 21, 2010, 05:49:22 PM »
Can you feel it miss?
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Offline Trainman638

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Re: Drivability issue
« Reply #6 on: May 21, 2010, 05:56:36 PM »
Yes, I can feel the lack of power on the road and I can feel the motor struggle. It sure feels like a miss to me. BTW: I just pulled my plugs. They look good. Gap is set to .050, NOT .060 as I said earlier. As I recall, I chickened out going all the way to .060. 
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95 YJ 2.5/ax5/np231. 4" superlift, 33" MT's, 4.0tb, 136amp alt, 19lb injectors, electric fan, smittybilt 8k winch, custom bumpers and rock sliders, rhino'd tub, header and ceramic coated exhaust.
67 M416 trailer painted to match.
96 XJ 4.0/ax15 My wife's Jeep and my new project.

Offline Jeffy

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Re: Drivability issue
« Reply #7 on: May 21, 2010, 06:03:18 PM »
But it's not a sudden lack of power?  If it's an intermittent lack of power then that would suggest a misfire.  This usually happens more when you rev it higher.

Overall lack of power would more then likely be something else.

If you think it might be the cat then remove it and look inside.  You should be able to see if there is any damage.
« Last Edit: May 21, 2010, 06:04:12 PM by Jeffy »
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My Jeep: http://4bangerjp.com/forums/index.php?topic=2783.0
"If the motor car were invented today, there is absolutely no way that any government in the world would let normal members of the public drive one."

Offline Trainman638

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Re: Drivability issue
« Reply #8 on: May 21, 2010, 06:15:25 PM »
Power is fine (for a 2.5) until it warm up. Once it's warm it misses or stumbles. If I shut it off, and restart with the engine warm then it misses at start-up. Thanks for the help, I'll pull the cat tomorrow.
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95 YJ 2.5/ax5/np231. 4" superlift, 33" MT's, 4.0tb, 136amp alt, 19lb injectors, electric fan, smittybilt 8k winch, custom bumpers and rock sliders, rhino'd tub, header and ceramic coated exhaust.
67 M416 trailer painted to match.
96 XJ 4.0/ax15 My wife's Jeep and my new project.

Offline sharpxmen

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Re: Drivability issue
« Reply #9 on: May 21, 2010, 07:17:14 PM »
Quote from: Trainman638 on May 21, 2010, 05:27:52 PM
It's a 40,000 volt coil.


ah, i missed the Accel coil part
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'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

Offline Jeffy

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Re: Drivability issue
« Reply #10 on: May 21, 2010, 07:27:32 PM »
Quote from: Trainman638 on May 21, 2010, 06:15:25 PM
Power is fine (for a 2.5) until it warm up. Once it's warm it misses or stumbles. If I shut it off, and restart with the engine warm then it misses at start-up. Thanks for the help, I'll pull the cat tomorrow.
That doesn't sound like a exhaust issue.  Maybe fuel pump going bad?  Can't be vapor lock.
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My Jeep: http://4bangerjp.com/forums/index.php?topic=2783.0
"If the motor car were invented today, there is absolutely no way that any government in the world would let normal members of the public drive one."

Offline Trainman638

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Re: Drivability issue
« Reply #11 on: May 21, 2010, 08:01:13 PM »
Fuel pump? Only when the engine is warm? How would that be possible? I'm learning as I go. ::)
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95 YJ 2.5/ax5/np231. 4" superlift, 33" MT's, 4.0tb, 136amp alt, 19lb injectors, electric fan, smittybilt 8k winch, custom bumpers and rock sliders, rhino'd tub, header and ceramic coated exhaust.
67 M416 trailer painted to match.
96 XJ 4.0/ax15 My wife's Jeep and my new project.

Offline Trainman638

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Re: Drivability issue
« Reply #12 on: May 21, 2010, 08:25:03 PM »
Maybe a stuck injector? Bad injector? More things to check....this is that "learning curve thingy" ain't it? I wear my noob badge with honor :pirate:
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95 YJ 2.5/ax5/np231. 4" superlift, 33" MT's, 4.0tb, 136amp alt, 19lb injectors, electric fan, smittybilt 8k winch, custom bumpers and rock sliders, rhino'd tub, header and ceramic coated exhaust.
67 M416 trailer painted to match.
96 XJ 4.0/ax15 My wife's Jeep and my new project.

Offline sharpxmen

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Re: Drivability issue
« Reply #13 on: May 21, 2010, 08:59:08 PM »
sometimes the pump gets hot in time too, so that might be the cause but i wouldn't rule out the cat

same goes for the coil though, once it gets hot you might get misfires - but the misfires are pretty distinct, so far sounds like you're losing power rather so that should point to fuel or exhaust or anything related to that (including sensors).
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'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

copperyj

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Re: Drivability issue
« Reply #14 on: May 22, 2010, 07:54:53 AM »
Mine did that.  Would start up just fine.  I would leave my house on the way to work, and I'd get about 1 mile away, and it'd start to miss and sputter.  Seemed like the more throttle I gave it, the worse it got.  My problem was the Crank Position Sensor. 

My jeep is a 93, 2.5L w/ around 200k miles.
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