Alright man Im not use to posting stuff on the web, mainly just a lurker to find out solutions to my problems but I am in a tricky situation. This is an outcry! My 2001 jeep cherokee sport has been having some major issues. It started off as only having 4 codes; 2 misfires and 2 o2 circuit codes. I changed all spark plugs, ignition coil pack, crankshaft position sensor, oil and oil filter, all four o2 sensors, 3 fuel injectors and the result came that only the misfires codes were able to go away... for a couple days and the o2 sensor codes remained. And the issues i was having would be having a rough idle, a loss of power when accelerating(it would take 2500 rpm to keep a speed of 60mph). However i noticed when i turn the car on drive it for a little bit turn it off and turn it back on, the power would come back to the default where it would only took 1500 rpm to keep a speed of 60 mph. Also ever so often when i try to surpass 3000 rpm it would studder and fluctuate violently to where i cannot go over 3000 rpm for ****. And now few weeks later i was going down the highway stuck in traffic and check engine light starts flivkering. I drive it to my job and find out that 9 confirmed codes have popped up(((((( .Now when i turn it on it would either start up viciously like if it was fighting for its life and slowly go to a state of regular rough idling or start up and completely shut off without idling. when it completely shuts off if i keep my foot on the peddle it would stay on but only if i keep revving it. I am a true amateur mechanic but ever since i purchased this car I've been slowly learning the ins and outs through the internet. I love my Cherokee and i love the community that goes behind it whether it be Youtube, Xj forums, or overall Cherokee drivers i pass by and greatly meet(One of the greater perks of owning a cherokee, we xj owners stick together ha). Im not ready nor am i planning to give up my jeep! Here are the codes
p1491 Radiator Fan Relay Circuit
p0443 EVAP system purge control Valve "A" circuit
p0300 Random/Multiple cylinder misfire detected
p0301 cylinder1 misfire detected
p0302 cylinder 2 misfire detected
p0306 cylinder 6 misfire detected
p0130 O2 sensor circuit bank 1 sensor 1
p0136 o2 sensor circuit bank 1 sensor 2
p0705 Transmission Range sensor "A" circuit (PRNDL Input)
AND 2 PENDING CODES
p0303 cylinder 3 misfire detected
p0304 cylinder 4 misfire detected
Im having my suspicions that it could be my pcm because of the codes with the o2 sensors not going away when i installed the new ones aswell as the loss of power only happening when i first give it a go orrrr maybe wiring could be the issue but then again i dont know jack**** it could be something completely different like a cracked valve of some sort. Please help any knowledge or past experiences is greatly appreciated!

 

Did not edit my post excuse my grammatical errors...spare me please

 

Find a used PCM and plug it in.

 

I should elaborate. That sucks that you’re having problems with your jeep, but awesome that you don’t wana give up on it.

When i’m troubleshooting something I go through a process of elimation. The easiest way to find out if it’s the PCM is to pull one from the junkyard or a part out. Make sure it’s a 2000 or 2001 matching the numbers on your PCM. I would also clean all the ground connections while your at it, Including the PCM ground on the passenger side of engine block.

 

Did you clear the codes after you did the work you described? They don't immediately go away on their own, especially the O2 sensor codes. Those in particular take a number of miles or on/off cycles without the computer sensing a problem for them to reset. You should clear them yourself with a scan tool. If you don't have one, you should probably get one, as I guarantee you you'll need it again in the future with this vehicle.

Additionally, when a 2000/2001 ECU senses a problem, it will try to compensate for it, often causing other codes to trip that are red herrings. I had a problem with cylinder six on mine, but at one point I had misfire codes for 1, 3, 4, 6 and P0300 for multiple misfires. Plus I somehow managed to trip a couple of unrelated codes while messing with it. If it were mine, I'd clear the codes, see what comes back and focus my attention there.

Primarily my biggest question would be whether the O2 sensor codes come back. If they don't, that would be a big pivot in the direction I would take next.

Also, if you try substituting another computer, make sure it's either from a 2001 or from a 2000 with California emissions. There were two emissions versions in 2000, CA and EPA. The EPA version only had two O2 sensors, so the computer from the 2000 EPA version wouldn't know what to do with the extra O2 sensors on your '01.

 

Also, let's sort this list a little to help focus you:

p1491 Radiator Fan Relay Circuit

This is unlikely to be causing your engine issues, but you need to fix it anyway. Check the fan relay in the Power Distribution Center (PDC). It's the black fuse box under the hood on the passenger side. Here's a diagram to help you find the relay (it's the upper left corner):

https://ww2-secure.justanswer.com/up...4_91093781.gif

p0443 EVAP system purge control Valve "A" circuit

This is emissions only and will make no difference in how your motor runs. Personally, I would ignore it for now, but it will need to be fixed if you have emissions inspections wherever you are. You likely have a vacuum leak somewhere in your evap leak system.

p0705 Transmission Range sensor "A" circuit (PRNDL Input)

This is probably a problem with your neutral safety switch or the connector going to it. I don't think this is related to your engine problems. Here's a link to a pretty good thread on that:

https://www.cherokeeforum.com/f2/che...-p0705-141863/


p0300 Random/Multiple cylinder misfire detected
p0301 cylinder 1 misfire detected
p0302 cylinder 2 misfire detected
p0303 cylinder 3 misfire detected
p0304 cylinder 4 misfire detected
p0306 cylinder 6 misfire detected


These are likely all related and all caused by the same thing. You could have an issue affecting all cylinders, or you could have an issue affecting only one cylinder and the ECU has pitched a tantrum. Clearing these codes and seeing which ones come back will help you determine that.

How you proceed will also depend on the next two:

p0130 O2 sensor circuit bank 1 sensor 1
p0136 o2 sensor circuit bank 1 sensor 2


These can be the root cause of your misfires above, or you could have multiple issues happening. We go back to the question I asked above: Did you clear the codes after you replaced your O2 sensors?

One other thing I would suggest to you is that you download a copy of the factory service manual. The FSM has information on practically every part on your Jeep. You can buy the PDF version from Pacific Coast Manuals for $8. Make sure you download the one for your year.

http://www.pacificcoastmanuals.com/j...e_manuals.html

 

Some good information from extrashaky here. Couple of additional thoughts.

1. Test your fuel pressure. I didn't see any mention of that and it is one of the first things I would do if it were in my garage. For a 2000, you need 49 psi, plus or minus 5 psi.

2. When you replaced the oxygen sensors, what brand of sensors did you install? NTK is absolutely hands down the best replacement oxygen sensor; it is the brand that came with your 2000 off the factory line. If you used cheaper ebay sensors, beware that many of these sensors are total crap. If you did install quality oxygen sensors, there may be a "common" root cause involved here like a goofy vacuum/exhaust leak of some sort.

 

To piggyback on this, if you don't have a fuel pressure test kit, you can usually borrow one from Auto Zone through their tool loan program. Some of the other parts stores also loan tools. They usually have the more common test kits for compression, leak down, block test, etc.