jeep_colorado

I own a 96 grand 5.2 limited.
Check engine light says 'multiple misfires' but it runs fine until i get up to about 45mph then it starts rumbling but only when the gas pedal is depressed about half way and the rumbling stops when i let go of the gas or I floor it. Kinda feels like the fuel is cutting out.
About two weeks before this started happening i changed my spark plugs and was fine for about 2 weeks. Then it started misfiring so i changed my spark plug wires, distributor cap and rotor. that didnt fix it so I rechecked the gapping on the spark plugs, distro cap and rotor position and firing order and still didnt fix it BUT it did make the rumbling LESS noticeable. I am stumped and cant afford to spend money on parts that dont fix the problem. Anyone have any advice on what could be causing this problem?

no fear

Friend off mine has the same problem. Has tried allot off things but still not resolved.
Good luck.

He has the 4.0L Grand Cherokee.

OrvisKrawler

what brand plugs were in it, what brand plugs did you put in it? did you keep the old plugs? if you did try putting them back in to see if it goes away, I would think it has something to do with either the plugs or something you did when you changed them, did you get wires switched around without realizing it, check the plug wires AGAIN and see if they are right with the firing order, I know you said you made sure they were right with the firing order but never hurts to double check and then check again lol

mr-warwagon

x2 start with the easy...and also make sure the base of the distrb. is tight ////////.......... does sound to me maybe fuel pressure has lost lost its touch(poss fuel pump or psi reg.) exspecially when you load it up (half throttle or more) a lack of fuel pressure will idle and light drive fine but higher speeds and heavy loads will cause it to break up... try this does it run rough and miss if you power power brake it ( hold your foot on the brake and hit the gas 1/2throttle or more) fuel pressure should be close to 49psi +2psi leaway at idle
note : you can buy a fuel pressure gauge at harbor freight or at a local parts store

no fear

Any luck in solving the problem you had with your Jeep.

jeep_colorado

not yet. checked the resistance in the fuel injectors and seem fine. waiting on some extra money to replace the o2 sensors but i am starting to think it might be the cheap spark plugs i put in it. just keeping the heep below 40 so it doesnt blow up on me. I will post what the problem was when i fix it. im betting it is the cheap ***** spark plugs i installed.