Rat999Salad

Hello, new to the forums and to jeeps in general. Just got a 2000 xj sport 4.0 6 cyl.

The seller told me injector 1 went bad, so he fixed it and everything was good but on my way home the CEL came on.

Went to the auto store to get a read and it said cylinder 1 misfire again.

Replaced the coil pack and spark plugs. Still have the CEL

It runs totally fine (i think) but it does have a slight putter to it.

Could it be heat soak? if so, what do i wrap exactly? the wires or the connection? and what do i use?

any help would be awesome. Thanks!

Rat999Salad

Could it possibly be a bad 02 sensor?

Firestorm500

It could possibly be a cracked head and/or blown head gasket leaking coolant into a cylinder.

Your Jeep has the 0331 head, which has a known and notorious factory casting flaw between #3 and #4 valves. Sometimes you can remove the oil filler cap and look down there with a flashlight and see where it is cracked.

I'm not trying to be an alarmist here, but on your Jeep it is a distinct possibility. Further diagnostic procedures keeping this in mind are needed.

md21722

I would do a compression check when its puttering and see if #1 or any cylinders are low. Could be a valve problem rather than a flat out head crack or blown head gasket. If the head comes off, I recommend replacing it with a TUPY or new head.

Rat999Salad

The head gasket is also new on it.
It totally runs great. Good pick up, starts easily. The only thing bothering me is the CEL. if that wasn't on id have no idea anything was wrong.

cruiser54

Buy a can of BG44K and add it to a full tank of gas.

Run it down to 1/2 tank and refill with gas. Run that tank down to about 1/4 tank before refueling.

Also, how high are you revving the Jeep?

was the previous owner a "granny driver" by chance?

Rat999Salad

I'll give it a shot.
Not sure who the previous owner was. Got it from a mechanic/Russian mob dude. Super sketchy but the price was right.
I drive it daily. On the highway and all. Get up to 70mph with no probs at all.
It has 160k miles on it too. Forgot to mention that.

Firestorm500

Somebody was already trying to solve misfire, CELs, probable coolant loss by replacing head gasket.

Since they didn't know about the head cracking issue, that the head should be totally replaced, they let it go since the problem persisted. It can still run fine on the highway.

160K is right in the middle of the bell-shaped curve when they crack.

I hope yours isn't, but.....

Rat999Salad

yea i really hope that isn't the case.
would i be able to see the crack? I'm gonna take a good look when i get home.

Firestorm500

Maybe. See my post #3.

peelman

Could be several things. If you can get a hold of a scanner that is able to read and record live data like fuel trims, it would help you determine what is causing your p0301.

cruiser54

Does it have a tach?

Rat999Salad

Gonna grab a can of BG44k today.
That stuff was hard to track down.

Not sure what a tach is...?

Looked for signs of a crack. Nothing obvious so far.

cruiser54

Tachometer as in RPM gauge on the dash.

How's the oil look? Not like a milkshake?

Rat999Salad

Yea it has a tach, nothing weird going on with it.
Oil is totally fine, been checking it everyday thru the dipstick and the fill hole.
All good.
The oil pressure gauge goes down to about 1/4 when I'm stopped, then goes right back to center when I start driving again.