little back ground.
95 Country 4.0
Replaced all of the following this past weekend.
Water pump- Not related to new issue.
hoses top and bottom- No issue
jeep was cutting out and heard whine from fuel pump. replaced fuel pump and ran great for 80 miles home Sunday.
Replaced starter- It needed it
Replaced Alternator bearings were going out on other.
Replaced Idler Pully-locked up.
Replaced belt
Fixed pinched tranny coolant lines
Installed Fan shroud. Finally found one at the JY.

So lets just say I've been busy fixing stuff haha. I know a lot of these things I have replaced/fixed wouldn't cause this issue but just giving some back ground info. I'm not a mechanic so my terminology may be off so just forgive me haha. (I manage computer systems for Arkansas DMV's so give me a break haah)

Here is my new issue and it has only done it once but I haven't driven it again since it done it on my street coming home from a test drive early today.

Going about 25 MPH I felt it hiccup very slight at that speed. (first thought was fuel pump again) but then I gave it some gas and it back fired (tail pipe) and missed. If it was fuel pump I would think the back fire would have come from the air box not the tail pip. That leads me to think something related to timing or distributor area but not sure. I then turned on to my street and gave it some gas and it missed pretty good. I put in reverse and gassed itagain and again it back fired missed. I put in natural and revved up and it sounded fine. I shut it off and started up fine. I have one idea about what it could be but not 100% sure ( Will check in morning). What I think it could be is a while back I had a bad issue (on a trail ride) where it would just shut down . I figured out that the distributor cap had pinched the 3 wires coming out of it and stripped coating. I split them apart and taped up good and it was fine since. I will check that to make sure my tape job is still fine.
I do have crank case pressure causing oil to come out of dip stick tube. (Not crazy amount. hardly any on trail rides only time I notice is when I go down the highway for a little ways above 55). I know that could be from ring wear. I have checked the PCV valves or CCV valves for blockage and they are clear. 297134 on the OD by the way. Also this morning when I cranked up the oil pressure seemed really high for just a little bit. ( When engine is giving out from ring wear what are symptoms?)

Is there anything else that could cause an intermittent hiccup/Miss like this? I am going to try to figure this out in the morning and would love some more things to check.

 

Three things.
First: Your CPS (crankshaft position sensor, not the cam sensor) can cause these symptoms. In the 4.0 engine this will happen at some point, so replace it with a qualitiy one (bit of a trick to reach it with some extensions) and if not solving the issue (in mine it did) you have that ticked off the list anyway. Because is WILL fail at some point.

Second: do a proper tune-up for not too many dollars, to get issues with that out of the way with symptoms like yours.

Third:"...causing oil to come out of dip stick tube" ...your level might be a bit too high, no oil should come out of these tubes, so check the level.

 

I will look into the CPS in the near future.

It has newish plugs/wires dis cap rotor button (within last 15K miles). Oil and filter less than 1500 miles.

Levels are correct on oil. I have researched it coming out of dip stick tube and it is cause from crank case pressure. Its a type of Blow By from what I have read. I check the fluid levels just about every time I drive my rig. It is a trail/ hunting rig so its not driven everyday.

 

If you have that much blowby, might be worth pulling the plugs and looking them over. 15K miles could be an eternity in an oil-soaked environment. Perhaps one has fouled leading to a misfire under load.

 

Good Idea. Would if one was fouled would it miss under load all the time or intermittent? I went down the road just a min ago and its running like a champ but I only went about 2 miles since its so late haha.

 

I've had them act up when and where they feel like it, lol.

 

lol. I will check these tomorrow as well. I am also going to take dis cap off and clean/check for cracks too.

 

ccp you stated valves are clean what about hoses?

 

Yes they are clear as well.

 

Plug wire was loose lol. At least it's good to go now.

 

is rear one getting vacuum at idle,front one still connected to air filter box

 

what kind of oil filter?? A failed filter will cause high oil pressure.

 

Yes it is getting vacuum at idle.
Yes still connected to air box. no blow by that way filter stays clean.

 

When it warms up the pressure goes back to normal. Wouldn't it stay high if the filter failed. Cant remember. I'm not sure the brand and its to hot to go look lol. Its not the cheapest they sell though I usually get a middle of the road brand.