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99 wrangler 2.5

1K views 14 replies 4 participants last post by  Digger84 
#1 ·
Hey guys new to the jeep world...I have slight miss...kinda like bad fuel around 2100...no cel! Just replaced plugs wires cap rotor button tps o2 sensor...any sugesstions or help would be greatly appreciated!
 
#2 ·
What brand O2 Sensor? NGK/NTK are the only O2 sensors that will work properly in our Jeeps. Specifically Bosch O2 sensors will cause the problem you are having. I had the exact same issue when I first bought my Jeep. It had a Bosch sensor installed by the PO. Swapped it out for a NTK sensor and have not had the issue since.
 
#6 ·
Common issue with no code but miss at 2 to 2.5 K rpm on the 2.5 engine is injector harness plugs to wrong injectors as for some reason guys tend to reverse which goes to 3 and which goes to 4

Just check wire colors on the injector plugs and if out of order change to correct

Don't know why miss shows up at those rpms but it does
 
#14 ·
Depends... How deep are your pockets and how much do you want to invest into the 4 banger for minimal returns?

The biggest would be regearing if you have larger tires
then there's the ol' cold air intake and larger/better flowing exhaust.

Most common small mods are the 4.0 throttle body swap and electric fan.
The 4.0 TB swap is super easy and just gives you a slightly more aggressive throttle due to the larger diameter. The 4.0 TB fits exactly in place of the 2.5 TB with no other modifications. IMHO though, not a big game changer.

The electric fan is supposed to reduce parasitic drag on the serpentine belt by getting rid of the clutch fan. Many say they notice some more power when going up hill, but it's been argued that the electric fan will cause the alternator to work harder thus cancelling out the benefits. In actuality though, if you use your wrangler as a DD and drive at higher speeds, the fan doesn't need to be on or wont come on and will save you some.

Also, you can get similar lb rated injectors from dodge neons that have 4 spray holes instead of the squirt gun stock injectors have. Super easy swap (I've done it in about 30 minutes). There is science behind better atomization and it should give you a better combustion with less fuel. Whether or not it is true for the 2.5, I don't know. Not a whole hell of a lot of difference, but i replace mine because I got the injectors cheap and I know better atomization is almost never a bad thing.

If your pockets are real deep, you could get roller rockers for your cams. Not a whole lot of people have done it though due to the high cost, but the science is there.

Other than that, you either need to gut every ounce of weight you can, swap motors, or trade it for the all mighty 4.0.
 
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