CommanderXJ

Hello all,

I am a noob here, anyways I got a 96' Jeep Cherokee Country back in September. Amazing little truck but I've been having a rather annoying problem with it since October.

Whenever the car is going up a steep grade or if I am accelerating at a steady rpm (about 2700 rpm to be exact) I hear a type of rattling noise. It's really only specific at this rpm and it doesn't happen beyond 3k. Here's what I did to the car since I got it.

-Replaced valve cover gasket
-New plug wires, plugs (copper core run of the mill champion plugs, was told these were the ones to get for this car) distributor cap/ignition rotor
-New radiator with all new radiator hoses and of course coolant flush
-New thermostat/housing/temp sensor
-New tranny line
-Replaced diff fluid/transfer case fluid
-Ran seafoam through the brake booster line (virtually no smoke)
-Sprayed some MCCC (Mopar Combustion Chamber Cleaner) through the intake (again no smoke)
-Complete fuel system clean (waste of money, did virtually nothing)

That's pretty much it. Most of the work I did myself minus the fuel system cleaning. But the car runs beautifully (even prior to all the work) and it gets between 16-19mpg in the city depending on how I drive it.

I am honestly out of ideas here. I noticed that if I ran 91 octane the noise would be almost non existent. The only thing I could possibly think of it being is that the timing was somehow thrown off. The car has 115k miles on it so it's still kind of a baby.

Anyone have any ideas?


Thanks! Look forward to reading your responses.

Abovetimberline

I would check your fuel pressure,it sounds like it is running lean,timing is set and you cannot change it.
You might try a higher octane if you have not already.

CommanderXJ

That's actually a strong possibility. But how could the fuel pressure change?

The only thing I didn't replace that was on my "to do" list was the fuel filter. I was told by the dealership that I should replace it, but they wanted 50 dollars for it and I figured that was a bit high considering I could do it myself for much less.

If it was a fuel pressure, wouldn't the mpg suffer a bit though?

Abovetimberline

The mpg could if the pressure is low,your best bet is to check the pressure and make sure it is ok,fuel pressure guages are cheap and another reason to buy a tool.