mmag1982

Hello,

I am currently facing a very frustrating problem with my 01' xj with a 4.0, 5spd manual.

I recently bought it, the car has only 30k miles, it was stored most of its life. perfect condition.

The problem is is a general lack of power and huge engine harshness in higher RPM's.
All usual maintenance items were conducted but that did not solve the problem:
- oil and oil filter
-air filter
- new spark plugs
-new oils for differentials, gearbox and transfer case
- a can of Injector cleaner for the fuel injectors
- oil and cooling systems checked for function and integrity

The symptoms are as follows:

1- repeated 0-60 of 10.5sec ( different drivers ), I am assuming an XJ 4.0 with a manual should at least be at 8 sec stock?, The engine responds to wide open throttle with harshness and some sort of hesitation with each new gear, for example 2nd to 3rd.

2- intense engine harshness at higher rpms and a "strangled" feeling above 3000RPM, the RPM climbs up slowly even when i floor it in 3rd gear for example. the engine just feels like a big grinder on the way to the red line past 4000rpms.

3- The engine shudders and vibrates when the ignition is shut off. In other words it takes the egnine like a second or two to shut off after the ignition.

4- The odd this is RPM idle is rock solid, no hiccups or fluctuation 600rpms, slight hissing sound from around the intake and water dropping out of the exhaust in the morning. No engine fault codes, nothing out of the ordinary

The frustrating thing is that my local mechanic and jeep shop say its fine!, and I am simply not convinced.My seat of pants feeling says something is wrong. I have driven a friends exact car , and it feels much faster and smoother ( stock )

Any thoughts on where to look, how to approach this?
My experience with engines says power and torque are always about air, fuel and spark timing but I'm not very familiar with how this specific engines behaves.

Appreciate some help from the experienced people here

myHEEPis.rad

how long was it stored before you got your hands on it, and have you emptied your gas tank before putting in new gas?? my only guess is old/bad gas.... my buddy had the same problem not to long ago with his jeep that he got that was sitting for 2 yrs before he got a hold of it. Ended up replacing everything before he realized it was really old gas . Good luck!

myHEEPis.rad

o o o.......and welcome to CF!

altrocker1

how much did it sit??? is it a posibility that the coil packs are corroded...could also have brittle or broken vac lines from sitting??? have you cleaned the throttle body?

i'll be honest, my rig runs way better when i drive it every day...sounds like it needs some more freshening up

altrocker1

also on the bad gas area...fuel pump may need cleaning

freegdr

gas turns to varnish when it sits to long