Time to work on performance and mpg

Sukpad89 · **Posted:** Thu Sep 01, 2011 7:16 pm

Now that I put some work into my liberty on the outside I think it is time to work under the hood. Intake, Exhaust, Spark Plugs, Wires, Sensors, Electronics, Fuel Injectors, etc..... I'm curious as to what people have done, what they used, and what were the results. More power, better mpg, happier Libby, happier me. I guess a good format for this is first say the order of the mods, what you would or do use, and what to expect for each mod. Hopefully we get a good list going here.

So far Im thinking of doing a K&N filter in the stock box, then a cat-back (IDK what kind to go with yet), Then spark. Just kinda go around the fire triangle (even though they made it a diamond)

tjkj2002 · **Posted:** Thu Sep 01, 2011 7:31 pm

Skip the K&N,slap in a cheap Fram paper filter,more then the 3.7 can use.Good cheap copper core plugs gapped correctly and changed every 30k,no need for fancy snake oil plugs.Keep up the maintenance and you'll be fine.For performance you can get the PCM reprogrammed by B&G and add a fastman throttle body.Besides that regear to 4.10's for the biggest performance boost,not a mpg boost thought.

Boomerang · **Joined:** Tue Jul 26, 2011 7:46 pm **Posts:** 184

so far i've only changed spark plugs. at just under 40k it had what looked to be the origninal NGK plugs gapped incorrectly, replaced them with Autolite 5224 copper cores. I will be re-replacing them this weekend after I Seafoam the thing. New plugs didnt change the mileage much, that still sucks. I put on an AMSOIL "Absolute Efficiency Air Filter (EAA201)" air filter ($29 bucks after paying for a $10 6-month membership).. Supposed to be somewhat comparable to the K&N version, but it looks like it does a more thorough job than the K&N in non-scientific testing.
Next week, changing the motor oil from regular 5W-30 to AMSOIL full synthetic 5W-30 hoping for some slight gains and smotther idle.

Sukpad89 · **Posted:** Thu Sep 01, 2011 7:43 pm

Thanks for the info guys. I already use full synthetics in every fluid I have changed. Im at about 35k now and I got it at about 28k so I'm not completly sure what the previous owners have done for upkeep on the thing although its pretty clean. (still getting the dog hair out from the previous owner) I guess I will just go through and do a complete tune up. I will also look into that device and TB upgrade. I'm just looking for a little more pep when I get my toe into the loud maker.

JeepinJarhead03 · **Posted:** Thu Sep 01, 2011 10:00 pm

duct tape works real good on the dog hair

lot cheaper than 5 rolls of those pet hair roller things too

tommudd · **Posted:** Thu Sep 01, 2011 10:03 pm

JeepinJarhead03 wrote:

duct tape works real good on the dog hair

lot cheaper than 5 rolls of those pet hair roller things too

X's two the last Peterbilt I bought the previous owner had a dog, no doggie smell but hair galore, 2 rolls of duct tape and about 4 hours and it looked like new. Gray dog hair and black carpet do not mix well :banghead:

Sukpad89 · **Posted:** Fri Sep 02, 2011 2:38 am

I know... Every time I think I got it all out I find more. I took the shifter boot off the otherday to tighten the shift lever and the darn thing was full of hair! Looks like the last owner had a golden retriver and maybe a german shepard or some other dog with similar hair, either way it is :juggle:

everytime

riptricket · **Posted:** Fri Sep 02, 2011 4:39 am

buy a pair of shoes... I hear they get excellent mpg!
:-)r

In all seriousness I think that tjkj addressed it the best.

sota · **Joined:** Fri Aug 07, 2009 7:44 pm **Posts:** 379

want to get better MPG?
go study the techniques used in "hypermilling" and apply them as much as possible. they work quite well.

does anyone know if the programming in the ECU will cut all fuel when under engine braking? in my one car it's definitely noticable and I haven't gotten a scanguage for the jeep yet to watch the injector pulse width and ignition timing.

Time to work on performance and mpg

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