I am the owner of a 1996 Jeep Cherokee Sport. It is completely stock with the 4.0L inline 6 cylinder engine and 4-speed automatic transmission.

Lately I have been having problems with the Cherokee running badly. For a few months, it has been running a bit rough when I first start it up after sitting for more than a few hours, but it always evened itself out and I never thought much of it. Now when I crank it, it always runs rough and never seems to fix itself like it used to after a few minutes of driving. It feels like one of the cylinders is not even firing or something. The Cherokee shakes a bit when at idle, like something is barely wrong but causing it to shake nonetheless. When I accelerate, the problem becomes very noticeable as the Cherokee seems to lack overall power and it still feels shaky and jittery like one of the cylinders isn't firing. Sometimes it evens out and drives smoothly like it used to, but almost as soon as I have to stop at a light or stop sign, it starts shaking again. Sometimes I can hear it backfiring when I accelerate.

Now I'm not the most technically/mechanically savvy person, but I had a general idea of what could be causing the problem. So far I have replaced the spark plug wires, distributor cap, rotor, fuel filter and checked all the fluids. I checked for vacuum leaks but there appears to be none. I changed the oil and oil filter (only because it was long overdue, not specifically because of this problem) and when it was coming out of the oil pan, it smelled almost like raw gasoline and it was water thin and black. I'm not sure if this is related to the problem I am having now, but I'm assuming there is a problem with one of the cylinders and gas is getting into the oil somehow.

If anyone could toss some ideas around as to what may be causing the problem I would greatly appreciate it.

 

air filter?

 

Air filter is fine. Looks almost brand new.

 

Clean out the Throttle Body and Idle Air Control with some Throttle Body Cleaner. I had an 89 Dakota that ran like garbage because of the IAC, ran VERY shaklily, stalled out when I stopped, and had no power. I'd floor it and it would shake for a few seconds until the idle raised a little bit and then take off. I'd recommend cleaning the IAC and Throttle Body. If there was a misfire, you'd have a Check Engine Light. If there is a CEL, use a Scanner to see what it is. Good luck and Merry Christmas.

 

Go to advance auto parts or auto zone and ask them to read the OBD II codes for you. That may reveal the problem.

It sounds like a misfire. I know these have issues with the CPS, (crankshaft position sensor). But that usually causes a no start... Hmmm.

 

Yea, if the CPS is bad, it will just crank and never start, which is my current problem. Gotta check the CPS tomorrow and hope it checks out because then it would be the coil because timing is already ruled out.

 

check your injectors

 

Fuel pressure?

 

Fuel lines inside the tank could be rotted, but that wouldn't explain the smell of your oil.

 

sounds to me like a misfire, or a dead cylinder, especially if you are smelling gas in the oil...

Here's an idea, but you gotta promise not to be stupid...

With the jeep idling, pop the hood and get on the left side of the motor (passanger side). Now, be very careful, and make sure you are not touching anything metal, on the car or on the ground. Go down the line of spark plugs, pulling each boot and putting it back. Cylinders that are firing will make the engine really stumble and hesitate when you remove spark. If you find one that doesn't affect the idle when you pull it, then you know there is something wrong with that cylinder, be it no spark or possibly a stuck valve (that might explain the back firing) or blown rings...

Like I said, don't be stupid, and just so I cover my butt, you probably shouldn't even do this.

But I've done it a million times, and only got shocked once, and that's because I had one hand on the motor when I pulled the plug, OUCH!

 

Replace the Sparkplugs!
You'll notice one or two of the plugs will be fouled out and out of gap tolerance.. My jeep does the same thing!
This doesn't fix the problem that is causing the plugs to foul out but it'll run like it should

 

I had this problem 9 years ago.



To your credit, I did replace the spark plugs and (if I recall correctly) it did fix that issue.


I moved from Florida to NC... it made the there and back ONCE as one of the moving vehicles. On the second attempted trip, my water pump blew up, leaving me stranded on the side of the interstate after just 10 minutes of driving.


I miss that old Jeep, but I definitely don't miss the many problems that vehicle had. I bought a Saturn shortly after that incident, and those things just never die. I think it's been out of commission once in the 8 yeas I've had it... the Jeep had problems on a monthly basis.

 

 

This seems to be happening a lot lately.

 

You get anywhere with this..im starting to think its a stuck valve but i need more opinions