Jeremy B

Hey guys unfortunatley this is my first post here but looking for a little help. I bought the Jeep a couple months back and have been very pleased up until now. The other day I was coming home from work and the jeep felt like it lost about half its power. I had to stop at a red light and it dies. Crank it back up and manage to get it to a gas station to check things out. About 1/8 miles before I get to the gas station the check gauges lights comes on and the oil pressure bottoms out for about 2-3 seconds then jumps back up to normal. I get to the gas station looking under the hood for anything out of the ordinary but nothing. So I decide to unhook the battery to try to reset the computer. Well that fixed my problem for the time being until I could get it home. I thought something had maybe put it in limp mode and all was well. Went to check it out again the next day and when I started it up same thing as before. It was cutting out real bad. It has now gotten way worse, it backfires out the exhaust like crazy and occasionally through the intake so I am thinking it is electircal related causing the afr to go crazy. Here is the kicker I naver seen any check engine lights so I thought that was weird. Pulled the gauge cluster and the light was missing so I took one out of the cruise control since mine doesnt have it and it lite up. I ran the codes cylinder misfire in 1 and 6 P0300, P0301, P0306. So far I have tried the cam position sensor, crank position sensor, plugs (NGK copper core), throttle position sensor, cleaned IAC and throttle body, unplugged the upstream O2 to see if it would clear up. I am lost at this point. Any other ideas? I thought maybe the oil sending unit was causing this but havent tried to replace it. I had a Jeep Liberty that needed the oil sending unit replaced and it would hardly idle sometimes. I changed that oil sending unit because the it was going crazy and it never had that idle problem again. Any help is greatly appreciated.

Jeremy B

Also forgot to add I did check fuel pressure it was about 45 psi.

Roler

Provide some more details regarding your Jeep, like year, engine etc. We will be able to help you better with that info.

Jeremy B

That might help LOL! Sorry its a 2000 Jeep Cherokee Sport 4.0 6 cyliner 4x4 with 173K on it.

Jeremy B

No one had any ideas? I need to get this thing back on the road.

syncview

Check your body grounds all of them including the PCM body ground.

Jeremy B

Where are all the grounds located? I tried the trick to re time it by lining up the cam synchronizer no luck.

Roler

Checking and refreshing the grounds is always a good thing. However, with the manipulation of the cam sensor, timing might have gone bad? you've throwns quite some parts at it already. Since it gives you a rather rough time atm, it almost sounds more than just an electrical problem.
I know that manipulating the distributor can throw things of, has it been taken out?
There are threads on this as well. Sure this post will bring it back under the attention of those with more know-how on this.

Jeremy B

It's a 2000 so it doesn't have a distributor.

CCKen

44.2 psi is minimum fuel pressure. You say it was about 45 psi. What exactly is 'about'? Is this pressure with the engine running? Low fuel pressure can cause problems if your fuel injectors are less than efficient.

If you can access a scanner that you can observe live data as the engine is runing -you can check the O2S cycling/voltage - low O2S voltage means the fuel air mixture is lean. If the O2S's are not cycling about every 2 seconds the O2S, or its heater circuit, may be bad. You can also see if the engine coolant temp and inlet air temp is functioning properly, both have an influence on fuel injector pulse width.

I'm not declaring you have a lean running engine but it's worth looking into.

Scanners are very useful in troubleshooting performance problems,

western-j-hawk

have you checked your coil pack

Jeremy B

Swapped the coil pack out last night. Everything seems good to go now. Thanks for all the input everyone.

Canary 33

Hi, I think I'm having the same problem. First of all, what is a coil pack? Is that spark plugs. I have a Jeep Cherokee 2001, L6, 4.0L (242 CID. My problem started with the temperature gauge going up pass the red 260. Then it goes back to normal and goes into the red again. I thought my car was going to over heat, I was looking for smoke to come out the hood. Since I didn't see the smoke, I thought everything was alright. It started making a noise from under hood and losing power. and I was smelling a burning smell. Finally, I pulled over and the engine cut off. I opened the hood and smoke was coming from the engine.I checked the antifreeze and it looked dark brown. So, I got it tow to my house. I started it up the next day after 5 tries. I'm getting some back fire and it seems the engine is losing power. The engine light blinks off and on. I get the codes PO300,PO302,PO303,PO304,PO305,PO306. Any suggestions? Thanks!

Jeremy B

Doesn't sound like yours is a coil pack issue. Its the long set of boxes that sit on top of the spark plugs. Honestly it's sounds like you damaged your engine by overheating it. I would start with a compression check.

Canary 33

I hope not. I'll start with a compression check. Thanks!