I've got an 08 2 door Rubicon auto trans on 35s... Mods include AEM cold air intake, viper throttle body, ripp headers, ripps recommended resonator, rugged ridge duel outlet muffler and the diablo programmer with ripp header tune...

I just don't feel like there's any power driving down the road. The jeep is constantly shifting in and out of od. I understand it's not a racecar but I know guys with stock 4 doors and no mods that have better drivability...

Should I find/pay to have it dyno'd or did I miss something with the combo of mods?

 

You didn't regear ...

 

All of this.

 

Just for the heck of it, a few old posts by the folks at Ripp. These were in some "should I regear or supercharge?" threads.

 

Sure seems like adding roughly 50 hp and 30 ft-lb of torque should feel at least slightly better than stock, not worse.

 

Depends what the torque and HP curve looks like. Most of the power was probably added at a much higher rpm than you are going to cruise at. There is not much you can do to improve power under 2500 rpm in that engine. Most of the gains won't start until 3k rpm. In fact, I would not be surprised if you lost torque in the lower RPM range. Counter-productive until you regear.

Also, more power is not going to help the shifting. Again, because of the above. When you run larger tires, your gearing is way into the "wrong" zone. You now cruise at an rpm that is very inefficient and does not produce enough power. Regearing will set you in an optimal area of power. Because you run larger tires, have more weight, etc, you need to be at an rpm well above when it was stock so that you are further into the power curve.

Honestly, even putting a super charger on won't help you. My light 2-door with the 3.6L engine and 3.73 gears sucked when I had 35s. I was 100 HP ahead of you. I went to 37s and 4.88 gears and it was like driving a go-cart.

 

Once you get your gearing strait, I have some thoughts.

First off, i'll be the first to tell you I haven't even attempted to squeeze more power out of my JK. I went to 4.56 gears with 33's, and it's got power plenty. With that said, I spent my earlier years dicking around with EFI live and bolt on's, making things go fast.

The first thing you need to do is hook your jeep up to a dyno. It's kind of late in the game, because you really needed to hit a dyno before you turned the first bolt to get a baseline. You have a bunch of bolt on parts, but you really don't know if you helped or hurt the engine efficiency. Exhaust is particularly sensitive with these new FI motors. I had a Dodge Ram 1500 2WD with a 5.9 in it that I learned the hard way on. I put a bunch of cash into a custom exhaust only to find out what I did HURT the power. I couldn't get it to tune in. High flow cats, headers, no mufflers true duals. Had to spend more money to get an X pipe installed, which solved the problem and put me in the plus on the HP side.

If you have someone that can write custom tunes for your specific vehicle, for your predator, that's good. The predator is a capable tool for those that don't have access to a real tuning program; like EFI live for instance. RPM Online did mine before I learned how to myself. To do it right, you need to record fuel trims, MAF sensor data, spark timing, and all that jive. The predator has the capability to save that data in a file you can export. I'm guessing if you have a Ripp canned tune, you've already downloaded the free software from Diablo. The people creating your tune should be asking for that data so they can adjust your engine settings to compensate for the bolt on's. Very rarely does a canned tune do much good other than giving you better throttle response. ALOT of people perceive that as more HP, but it's not.

Engine tuning is an art. Cold air intakes for instance. I always thought that was a cute one. Most factory air boxes pull air from outside the engine compartment, usually the fender well area. Outside air is relatively cool. Many of the so called cold air intakes pull air from the engine compartment, which is way hotter than the outside air. Go figure... I always tell people to keep the stock air box, and just swap to a high flow air filter.

 

regear regear regear

 

You should have saved all that bolt on gimmick stuff and invested in some proper gears. Throw some 5.13 gears in there and it will be a different jeep