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Discussion Starter · #21 ·
I've done the leak down test on cylinder 1, I've got a sticky exhaust valve. I have not messed with the distributor, cap, or coil. Sounds like it's all next on the list. I'm in Ankeny, Iowa. Thanks for the offer, appreciate it.
 

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I still say o2 sensors. Sometimes when they go bad they can throw misfire codes. Had an s10 and was throwing 4 and 6 misfire. Tried everything and code kept coming up. New o2 sensors and never threw another cel
 

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Discussion Starter · #23 ·
I'll prolly replace the O2 sensor while I do the exhaust manifold. Thanks. There's only so much that can be wrong lol
 

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is the valve sticking, or gunked up with carbon. I use Mopar combustion chamber cleaner in the throttle body. Its a foam that sticks to the carbon deposits. You spray about half a can threw the throttle body and a vacuum line on a warm running engine. Shut the engine off and let it soak for about 20 minutes. Start it back up, and finish the can into the throttle body and vacuum lines. Works like a dream. sure beats pulling a head.
 

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Discussion Starter · #25 ·
Yeah I've seafoamed the **** out of this 4.0. Throttle body, oil and gas all at the same time. Ran it for about 100 miles and changed the oil. Oil only had 300 miles total and it looked like it had 3000 when I changed it. I'll look into the mopar deposit cleaner for sure. Yeah last thing I want to do is pull the head, so basically doing everything other than the head trying to resolve this issue. I'd rather buy tires or a lift for $500 than re-do the heAd. Even though it'd be a learning experience and I wouldn't mind doing it... All except money and time. In that order.
 

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Seafoam is nice, but doesn't compare to MCC. IMO.

Is the valve making a tapping noise? You can pull the valve cover off and run the engine and look for any sticky valves. You tube has a ton of videos on it. May give you some insight. Good Luck.
 

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Discussion Starter · #27 ·
Yeah I'll do that when I pull the valve cover off to get a new gasket on there. Seen a YouTube video of "ericthecarguy" with him pulling the valve cover off and putting paper clips into the top of the valve rods, where the oil goes through. Suppose to keep it less messy while you're checking things out? Might change thermostat as well. Any suggestions on which temp thermo to run? Guy at parts store said they have 160, 180 and stock is 195
 

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More trouble shooting is in order for your jeep. Its strange thatll youll only get the misfire when it throws the codes. Do us a favor and copy down every code that you get, the actual P0*** number, when you scan it and post them up on here. This will allow us to help you out some more.
I have
P0300-p0306 all cylinders misfiring.
I’ve done a full tune up changed injectors plug wires spark plugs oil change etc. I have oil in my old air filter. Same problem as this dude apparently
 

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I have
P0300-p0306 all cylinders misfiring.
I’ve done a full tune up changed injectors plug wires spark plugs oil change etc. I have oil in my old air filter. Same problem as this dude apparently
What year jeep ya got?
 

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How about the distributor and coil? I'd go with the coil first, you can at least pull the cap off the distributor to look at the contacts. If they're burned out, then that will need replacement. Theres also a cam sensor inside the distributor body, this controls the fuel injector sequence. If there's an issue with that, it could be the cause for your issue. Problem is figuring out whats exactly going on and causing the misfire. Have you checked for spark at each plug? Do you have fuel pressure? You can get noid lights to see if your injectors are getting the signal to fire. Many things you can do before replacing more stuff. Do you happen to have any other codes that accompany the misfire codes?
 

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How about the distributor and coil? I'd go with the coil first, you can at least pull the cap off the distributor to look at the contacts. If they're burned out, then that will need replacement. Theres also a cam sensor inside the distributor body, this controls the fuel injector sequence. If there's an issue with that, it could be the cause for your issue. Problem is figuring out whats exactly going on and causing the misfire. Have you checked for spark at each plug? Do you have fuel pressure? You can get noid lights to see if your injectors are getting the signal to fire. Many things you can do before replacing more stuff. Do you happen to have any other codes that accompany the misfire codes?
No only “random misfire” and then each cylinder misfire. I changed the fuel pump and filter first. I changed the cap and button to the distributor also. I don’t know much about the cam sensor though that might be worth looking at
 

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No only “random misfire” and then each cylinder misfire. I changed the fuel pump and filter first. I changed the cap and button to the distributor also. I don’t know much about the cam sensor though that might be worth looking at
Its an easy replacement, you pop the cap off the distributor then the rotor comes off. Its the flat black plate with the plug connected to it. Try some of the checks first that I outlined, it will prevent some frustration from money lost to good parts being replaced. Look up how to use "noid lights" and check your injector firing sequence.
 
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