ChadXJ

Now since I've had my XJ its always been a hard starter. Sometimes it starts faster, sometime slower, Hasn't got worse.

Check engine light came on a few days after I bought my XJ.

I brought it to autozone and it has multiple cyclider misfires. So we made the decision that it must be an error. So we turned the light off and all was good.

I have no performance issues at all. This XJ only has 80,000 miles. It runs soooo good. I've only replaced the alternator. Thats it so far.

Anyways. Couple days later the check engine light comes on. I pull it in Autozone, and we hook up the CPU, same error. Just less cylinders now. So we turn the light off again.

Now mind you that I have no performance issues at all. All seems to be running great!

Now a couple weeks later the check engine light comes on again. I stop again, and it just says Cylinder 1 Misfire.

So I take my Jeep to a local mechanic, an honest one.

We pull the coil together and check the spark plugs, they are fine. We pull a few, and they seem like they were changed before I bought the vehical or sometime before then. They are copper that only last about 30,000 miles, but nothing is wrong with the ones in there, they arent the stock ones.

So we check the pressure guage, thinking it might be a fuel pump issue/fuel pressure. I doubt it because it doesnt get any better when I flip the key back and forth before I start. Same either way.

My fuel pressure is awesome. When the key is turned on it goes right up right away, and when started it maintains.

We spend about an hour trying to figure this out. He couldnt find his Chrysler chip to see other stuff.

It's not fuel pump, spark plugs, or fuel pressure.

Was told it could be crank sensor by a another mechanic? I don't know.

Anyone have this problem before, or similar?

It's an anomaly.

Thanks all feed is appreciated.

ChadXJ

Any takers?

country_boy454

Thats how mine started out and it turned out being my CPS.

ChadXJ

Hmmm... I'll check on that once I get off work.

How much does the CPS cost and how hard is it to install?

Any other comments?

ChadXJ

Any??

Mattpar

its not hard to install. If you can replace a altenator, you can do the Crankshaft position sensor. its located on the top of the bell housing of the trans, on the drivers side. 2 bolts hold it in. 10min job tops

98 JeepJeep

If a CPS goes out you lose ALL Spark and have NO Fuel pressure.....your issue is elsewhere.

Next thing i would do is Check the coil rail and then put a set of Noid lights on it....00+ have a Sticky Injector issue due to Heat soak and the way the manifold was designed......If you Search Miss-fire you will see alot of others with your same year that have done the 4 Pintle Injector swap and the issue is Gone.

A miss-fire can be slight and easy to miss specially only on ONE cylinder. Your ECM is telling you there is a issue......deleting the code wont fix it.

ChadXJ

Thanks man you've been really helpful. I've searched the misfire and saw alot of varied fixed, and problems. Thanks. How much is the swap? What has to be swaped?

ronsp8

Check your EGR valve.

Mattpar

if it is consistency the #1 cylinder, you can swap the injector, coil, spark plug, etc with another cylinder and see if the code will follow the faulty part.

Tural

swap the coil first. i swapped out the injector wires on my rail between 1 and 2 and it didn't even set off a code. 2000 is a coilpack, isn't it? see if you can swap the coil.

98 JeepJeep

i dont think you can just swap One coil...i believe it is a rail and there made together.

98 JeepJeep

dont check to hard you wont find one on a HO 4.0

BURTON159

I just went through the exact same problem with my 2000. It ended up being a cracked fly wheel. The sensor near the flywheel were telling the CPU it was out of time so I was geting the check engin light and same code as you. Got flywheel replaced for $300 and everythin is good.

99KeeSport

Damn, my misfire turned out to be NO COMPRESSION in cylinder one. I'm guessing a valve issue at this point since every item of the ignition system has been replaced and tested.