Topic: ok now what?!?!?!?!?

[moosin88]

well just put on the 4.0 tb and 4.0 tb spacer. but when i start it it idles rough for about 15 seconds then it smooths out and the check engine light comes on at the same time and runs a little high on rpm but still smooth. and buy the way no hesitation when stabing the throttle. it got dark so i couldnt search for any answers but any place i could start would be helpful.thanx

[Jesse-James]

Mine acted funny for about a week, rough at times, high idle at times. Once the computer "learned" it, everything smoothed out.

[Sidscan]

How about some specifics on your vehical?  If it's an auto make sure you spaced the throttle bracket up the same height at the spacer.  Even it it's not an auto, if you don't, your throttle cable maybe sticking.  Make sure you clean the sensors good to get the crud out.

After I reset the computer it took about 50 starts for it to stop doing the high revving so often.  It took raising the Throttle cable bracket to get my auto to shift correctly.  After I changed the front O2 sensor the idle also smoothed out.  I don't drive it alot so it took about a month and a half for the computer to learn.  This is on a 97 auto 4banger.  Lots of luck.

[Sidscan]

Sorry I did not read your question right.  Sounds like it is one of the sensors.  Did you reuse your old?  If you knew you had no problems with the old  then I would reuse them or get new.  Check to see if all your wires are snug on sensors.   Make sure the sensors are on tight, cleaned and straight (important).

Reset your computer by disconnecting your battery.  About 50 starts will make it relearn.   :D

[jwrape]

Yea, give the computer time to learn the new setup. Mine Idled high for about a week of driving on and off and finally settle down.
The computer is just not used to the new hardware.

[moosin88]

thanx guys i reused all my 2.5 sensors and they worked before. ive started it maybe 15 to 20 times and even took it down the highway a couple of miles. i then swapped in my old 2.5 tb and it still runs like crap the only thing i can think of is maybe the ias sensor on the side is no longer any good. i dont know maybe ill just drive it for a while and maybe the jeep gremlins will go gremlin someone else lol.

[chrisfranklin]

Yeah, I did a cheap used 4.0 TB swap about 4 years ago and had all sorts of problems with it.  Just pulled the thing and went back to the 2.5 for about 3 years. Then, ultimately, picked up a fabricator job on everbody's favorite over-charging auction site.  This bored out 62mm job at $100 seemed to work ok this time -- not sure why though.

Just that, with any of the mods you do to a 2.5L on the intake side, you are not dealing with a Mass Air Flow sensor.  Instead, the engine is going to adjust based on Intake Air Temp (IAT), Manifold Air Pressure (MAP) and RPM.  

So, if you open up the intake with a 4.0 TB + some kind of cone filter on a three inch metal tube, your MAP levels are going to drop and you are going to run lean -- low end torque is affected. Furthermore, you may "lean out" because your engine is sucking more hot air, too (not that the original airbox set up was any kind of cold-air magnet, itself ).

The solution to this with the no-aftermarket-chip 2.5s is to use an adjustable MAP sensor from Turbo City or elsewhere.  This will help you manually richen the fuel curve after you add intake upgrades.  Other thing to do, of course, is use some kind of CAI kit, so at least hot-air won't be screwing you up to bad.  Don't think the new JKs have this issue like the YJs and TJs do -- think JKs Caravan engines use Mass Air Flow.

[jwrape]

Yeah, I did a cheap used 4.0 TB swap about 4 years ago and had all sorts of problems with it.  Just pulled the thing and went back to the 2.5 for about 3 years. Then, ultimately, picked up a fabricator job on everbody's favorite over-charging auction site.  This bored out 62mm job at $100 seemed to work ok this time -- not sure why though.

Just that, with any of the mods you do to a 2.5L on the intake side, you are not dealing with a Mass Air Flow sensor.  Instead, the engine is going to adjust based on Intake Air Temp (IAT), Manifold Air Pressure (MAP) and RPM.  

So, if you open up the intake with a 4.0 TB + some kind of cone filter on a three inch metal tube, your MAP levels are going to drop and you are going to run lean -- low end torque is affected. Furthermore, you may "lean out" because your engine is sucking more hot air, too (not that the original airbox set up was any kind of cold-air magnet, itself ).

The solution to this with the no-aftermarket-chip 2.5s is to use an adjustable MAP sensor from Turbo City or elsewhere.  This will help you manually richen the fuel curve after you add intake upgrades.  Other thing to do, of course, is use some kind of CAI kit, so at least hot-air won't be screwing you up to bad.  Don't think the new JKs have this issue like the YJs and TJs do -- think JKs Caravan engines use Mass Air Flow.

Another way to run richer is to move the Air Temperture Sensor from the intake manifold out onto the intake tube where it gets colder air. This runs it richer.
Also adding Mustang Fuel Injectors could make it run better with their better 4 hole tips as opposed to the single holed tips now.

[dexetr30]

So, after reading all of this... would it be better for me to just leave the 2.5L t.b. on my tj? Sounds like a horror story. Read through Jeffys' article again on this and it all makes sense but from what I'm reading here..... :?

[jwrape]

So, after reading all of this... would it be better for me to just leave the 2.5L t.b. on my tj? Sounds like a horror story. Read through Jeffys' article again on this and it all makes sense but from what I'm reading here..... :?

NO, the benifits FAR out weigh the few that have issues with the installation.
I put mine on at 177k miles and it made a large difference in how it performed on the bottom end, it may have helped on the highway too but I definately noticed the lag between 500-3000 rpms was a lot less.
Definately a must do  for these little motors.
Don't let the horror story scare ya, just follow Jeffy's instructions and it will work fine.

[jwrape]

So, after reading all of this... would it be better for me to just leave the 2.5L t.b. on my tj? Sounds like a horror story. Read through Jeffys' article again on this and it all makes sense but from what I'm reading here..... :?

Also if you are planning on trying the 19lbs. injectors, then I would definately say you will need the 4.0 TB for the extra air flow.