So I am so fed up with my jeep right now..... I cannot seem to fix it. My old motor threw a rod in the first cylinder. I replaced it with a used motor. When I got the new motor in it started right up, but it was definitely missing and had pretty bad lifter tick. My first project with this motor was i replaced the lifters, which got rid of the ticking completely, and the engine didn't seem to be missing. So I drove it around a bit and I noticed that it seemed to be missing a little bit still and I had very little power over 3000 rpms, so I took it back home, got some new platinum spark plugs and an air filter just because the old one was starting to get a little dirty. After I put all the new plugs in I started it back up and it sounded alright, but as soon as I got down the road a bit I had little power and it started missing pretty hard and back fired a couple times. So i turned it right around and talked to a friend of mine and did a little bit of research. I then decided to replace the camshaft position sensor. It drove ok but still didn't feel right, so I drove it a bit more and once again missing and little power over 3000 and the check engine light was flashing and i could not rev over 3000, kind of like the computer was restricting it, which didn't happen till it was pretty much at temp. And i forgot to mention that i hear squealing over 3000 as well, i'm almost positive its the belt but it is plenty tight. The next thing i did was i got the codes read and it was throwing multiple cylinder misfire, cylinder 2 hard misfire, and cylinder 6 hard misfire. I started it again when it was cold and listened to the fuel injectors with a stethoscope and all of the were working properly, so i drove it again got it up to temp and and the check engine light began to flash again, i parked it and listened to the injectors again. Sure enough the injector on cylinders 2 and 6 were not working. I then went to the parts store again and bought two injectors put them in. It started it and it sounded decent. I drove it and it was running better than before and it felt like i had just about all of my power back. When it got up to temp same s***. The light flashed and again cant rev over 3000. Listened again and the new injectors were not working. Then i searched forums some more and heard about a heat soak issue with the 2000 and 2001 cherokees. So before i went and bought some heat shield i used tin foil to test the theory. I drove it again ran ok until it got to temp then once again check engine light and revs limited. i let it cool down and when i started it again it ran like complete garbage. i forgot to mention that there is a serious banging that sounds like the exhaust accompanied with power loss. This is where i am at right now and i am ready to go nuts. Please help......

 

and sorry about the length of that, i just wanted to get pretty much all the info out.

 

Have you cleaned all the underhood grounds and checked the connectors @ the PCM? How did this all start, has the vehicle ever been submerged? Did you swap the electronics along with the engines? Old engine ran fine till KaBoom?

 

The grounds are all clean. Can one ground cause all this? The pcm connectors are all in all the way. It all started after the engine swap. It has never been submerged. And the old engine ran perfect until it blew up on me. The only thing that could have damaged anything was one piece of shrapnel blew through the block on the drivers side, but i did not notice anything damaged by this.

 

What year Cherokee is this?
Were the old & new engines for the same production year?
Did you keep and use the PCM, harness & sensors from the the new motor?

 

I would try the recommended copper champion plugs and not garbage platinum.

 

"I replaced it with a used motor". Did you hear or know anything about

the used motor before you bought it?

 

Do a block test, and a compression test. Sounds like you may have a blown head gasket or cracked head.

block testers are only 25 bucks at autozone. And they have actron compression testers for 26.

http://www.autozone.com/autozone/acc...ier=391378_0_0_

 

My jeep is a 2001. So I looked back at the receipt from the motor it was out of a 2000. And I used the same PCM, I have never heard that it would need changed with the engine.

I will consider going back to the coppers, but I had the problem when the coppers were in beforehand.

What I know about the motor I got was it was from a 2000 jeep cherokee that is totaled in the rear-end and had 72,000 miles on it. I was really nervous about doing this at first but if treated right these 4.0s are pretty close to bulletproof, well I thought so until mine blew up.

I don't have anyway to get it to an autozone the nearest one is about 30 miles away. And the nearest other parts store 25 miles away. I inspected the head when I changed the lifters and I didn't notice and cracks but I guess I could have missed it somehow if it was super small, I know these heads are known to crack do to poor casting. But I changed the head gasket when doing the lifters.

Thank you for the input, I'm considering all possibilities.

 

two things... many 0331 heads crack and will cause engine failure. get a block test done to verify that the head isn't cracked.

Second, check out the CAT. A bad cat can cause some of the symptoms you describe.

 

So i have been looking at other forums and tell me if you think any of these is a very likely culprit.

Small crack in head (mentioned on this thread)
Cracked intake manifold
cracked exhaust manifold
MAP sensor
Vacuum leak
dirty fuel (the fuel in it is old, and i know that the fuel that contains ethanol does not last as long)
coil rail
broken wires in main harness from moving around installing new motor.
pcm not bring from this motor (mentioned in this thread)
timing off
lower cat bad and creating back pressure

Just some ideas ive had/found. Tell me if my symptoms point strongly to any of these or some thing i didnt mention

 

i did forget to mention earlier that i replaced the cated downpipes that these have but they do have one more cat as well could that me my culprit. and ill try and have a block test done.

 

Loss if power over 3000, I would check intake manifold for leaks first. If it is fine, head gaskets would be my next guess. If the cat was plugged up, it would cause same symptoms

 

Jeep is going into limp mode. When this happened to me, I found it was a clogged cat.

 

Is there anyway to test and see if it is the cat? I would rather not just buy one and have it be something else.
Thanks for the input everyone.