Hey guys I have a 2001 Cherokee Sport. It has a rough Idle and it sputters. While driving and at idle. I hooked scan a scan tool and it got the code PO300, PO301, PO304. Which stand for random multiple misfire, cylinder 1 misfire and cylinder 4 misfire. Now I can't figure out what would be causing it. It;s not pugs I replaced the a couple thousand miles ago. It's coil on plug so it's not plug wires. It has a new cam position sensor. I ran gas treatment to make sure it wasn't water in my gas twice. So I am at a loss. Any help you could give would be great. Thanks in advance.

 

Bump

 

clean out your TB. maybe your vac lines are leaking somewhere.

 

Thanks I'll check those things and let you know.

 

Well I cleaned the throttle body and checked all the vacuum lines. None of the lines had any issues. So I cleared the codes and took it for a test drive check engine light came back on and still ran rough.

 

o2 sensor? check your exhaust and your catalytic converter, sometimes if they are leaky or rusted they can cause the jeep to run rough. maybe try running some seafoam through your TB if you haven't already.

 

The cat and exhaust are ok, I already checked them, haven't run any seafoam. O2 senor would pop a code though wouldn't it?

 

Since it`s specifying #1 and #4 try disconnecting the plugs or injectors one at a time for each of those and see what happens...If it truly isn`t the plugs or injectors you`ll notice a change instantly..If you unplug one and nothing happens you`ll know there`s something wrong with one of those.

 

I have coil on plug so I can't unplug the the spark plugs without* unplugging all of them.

 

he means injector plugs. but that is most likely not the issue i have the same problem with mine on 1 and 4 some times to it comes from a leak in the intake manifold could be a bad gasket or something. does it have a problem starting to or is it just the misfire. i did every thing you have done as well and nothing worked i also tried moving the injectors around and replacing the o rings and it always comes up in 1 or 4. try spraying some carb cleaner near the intake manifold if the idle comes up that is you issue and the intake manifold should be checked to make sure the mounting surface is flat and the gasket is not leaking.

 

what plugs are you using you might want to stick with the ngk's that came in it

 

Sometimes it chugs a little but it always starts.

 

I have champions in it. When I got it it had Autolites in it.

 

switch back to the ngk's that should be in there but first get some carb cleaner and spray it around the intake manifold if the idle changes that is your problem

 

ok I'll try that