Ralph77

When this thread first started I wanted to bring that up.
But best I could tell is he did not say what head used.
One from the '00 or from the '98.
If he used the '00 head he is doing the reverse of what most people do.
Most people use an older head in an '00 or '01.
Not a 0331 head in a '99 and down.
The exhaust ports are smaller on the '00 head then the '98.
And I tried to determine if using a '98 exhaust manifold with a '00 head would matter.
I found this:

https://jeepexhaustadapter.com/exhaust-port-sketch/

But it is the opposite of what he is doing.
We need to see how a '00 head exhaust port compares to a '98 exhaust manifold port.
Cause not knowing any better my first thought was an exhaust leak.
But trying to figure it out gave me a headache, really did not know what I was talking about, and I just gave up so I did not post.
Until now. LOL.

cruiser54

You mean it might not be the PCM??????

Thanks for bringing a breath of fresh air to this thread!!!!

MaskedMallard

Let's eliminate some possibilities.

Do you have a code reader with live data?
- Any pending codes?

Whats your fuel pressure with KOEO?
Whats your fuel pressure at idle?
What spark plugs are you using? What gap? How's your ignition system?

Did you replace anything (sensors / electrical) with non-OEM parts?

I might have missed it, but which cylinder head are you using?

Post pictures of your mechanical timing, with you having everything lined up.

doublechaz

I'd like to point out that you can't figure out if your cam timing is right by looking in the spark plug hole and seeing the piston "at the top". Find a video about how to degree a cam. You'll need a depth dial indicator that can reach down through the plug hole to the top of the piston.

The other main point to watch is that there is no sensor telling the PCM what year block you are running so we can't just say it's the wrong year block and be done. You have to match up the primary operation systems you have bolted to the block with the matching ECU. The ECU needs crank and cam position (sync), injectors and spark system (fire), MAF or MAP and O2 (AFR). Those are enough to make it fire and run. Each of those systems for the 98 ECU have to use the parts from the 98 engine. If that requires an intake swap to allow them to bolt up, then you have to sort out if the ports can match up. If that means you need to swap crankshafts to match up... you get the idea. As long as you are able to use the 98 sensor suite on the 00 block, then the 98 ECU will work. Mess up AFR and it will run like crap. Mess up fire and it will not run, though it may sputter. Mess up sync and it will not run though it may sputter.

I left out oil pressure as I'm pretty sure the 98 ECU doesn't have a shutdown on low/no oil pressure feature, but on newer stuff that can be part of the critical needed to fire list.

97grand4.0

There's a guy, in fact a couple guys, on the jeep forum that says he did the swap in 2013, used the 00 head on the 98 block into the 00 xj, thus avoiding all the exhaust and manifold issues. Also had to swap in all the sensors and pcm from the 98. The flexplates, from my research appear the same 96 to 01. Sounds like you may have to change the electrical connectors to a sensor or two as well.
His post sounds legit but it is the internet...

Rchaxj98

i apologize for the plain/lack of detail post. let me see if i can explain myseld a little better.

i had a 98 stock engine (no internal modifications). that i replaced with a whole 2000 XJ engine. the head, the block, and intake manifold are how they came from factory and mated to each other. before piting the engine from the 2000 Xj in to the 98 XJ i rebuilt it to make sure i had a longer lasting engine. took the block go get bored out .030 to fit the new pistons and resourfaced the block along with checking the head for cracks or warping and also resourfaced by the machine shop. once the machine shop work was completed. i started to put the engine together. same crank, same conecting rods, new pistons. then mated the block to its same head just resourfaced to ensure a good seal. put it all together. with the same intake manifols it came with. and istalled it on the 98 XJ using the "flywheel" from the 98 engine. and torque converter. i figured the engine was working properly with the same sensors. everything was runing perfect besides the very low compression on piston 1 and getting lots of blow by dumping oil. i didnt even had the check engine light when pulled the 98 original engine. now i left everything in the 98 XJ the same way it was same injectors, same distribuitor, literally just replaced the block and head amd intake manifold from a 2000 XJ.

-I have a engine code reader. only code appearing is P1391 (1 of 1) jeep stored Loss of cam or crank

-i installed a fuel pressure gauge on the fuel rail so when fuel pump primes its at around 55 psi. once it starts i have to accelerate to keep engone running. since the gauge is liquid filled to try to stabilize the needle and with engine vibrations it reads from 50 to 60 psi.

-spark plugs are the same ones i had before pulling the engine they were working perfect Champion RC 12LYC i believe they had the gap preset by manufacturer but i bought a little tool and made sure it was accurate. also added dielectric grease to ensure no rust or moisture woild affect them.

-ignition system is an ACCEL Coil, with a performance accel cap, rottor and spark plug cables, again every contact point with cable has been lubricated with dielectric grease.

- i did not replaced any sensors. just unplugged, removed to the side. and mounted them and use everything again.

-Im using the same head that came with the engine from manufacturer along with the intake manifold. only thing i changed was the camshaft to try to get a little more power.

- for the pictures that you are requesting. i would have to tear apart the engine again. remove belt, remove alternator, remove iddle pulley, remove water pump pulley, in order to remove the armonic balancer and remove the timing chain cover. is there another way to do this ?

97grand4.0

Wow, I need a stiff drink

MaskedMallard

Do you have access to an Oscilloscope? Are you able to back probe the Camshaft / Crankshaft sensor(s) to see what type of signal you are getting?

I bought something like this, so I could see the wave pattern from sensors. This should help you understand what the computer is / is not seeing. If you have a good wave pattern at the sensor, you might have to back probe into the wiring harness, where it plugs into the computer, just to make sure your wiring is good.

https://www.walmart.com/ip/2-in-1-In...iABEgKqrfD_BwE

awg

Can also be signal out of sync

did you check the dizzy setup yet ?

The last couple of guys with this issue turned out to be cam sensor

Rchaxj98

So im super exited to tell you guys that I've drove it to work. And I have offially put the first 30 miles on it. I'll explain how I came to figure out and how I fixed it.

So I removed the distributor to check again for like the 10th time what was I doing wrong with the timing. And if I was skipping a tooth or something. Installed everything back together and I asked my daughter to start the XJ but to pay close attention to my signals just in case I needed her to shut it off quickly. Now keep in mind I placed the distributor in the engine but I did not fasten it. Or used to bolt to hold it. I literally used my body weight to hold it in place and I wanted to see what would happen if I turned it clockwise or counter clockwise. So I started with setting the engine to TDC. Erasing the error codes and setting the distributor to the 3 o clock position which is where it actually sits once its bolted to the engine. Then asked my daughter to start it. With the engine running I started to turn it counter clockwise. To see what would happen until it died. Then turned the distributor back to 3 o'clock and asked her to start the jeep again. Then I started to turn the distributor clockwise. It took from 3 o'clock to right about 4 o'clock for it to idle sweet and calm. Thats when I told her to shut it down. I removed the distributor set the engine back to TDC and grabbed my grinder. Cut the ears of the distributor. And do everything all over again turning it clockwise and this time actually fastening the distributor with the horse shoe clamp that comes with it and tighten it pretty good. Went in a first test drive. For 8 miles came back home. Replaced my idle control valve for a new one I had as a spare. Removed the battery, let it clear the memory of the PCM. And now I'm driving it down the highway at 65 mph no issues running smooth. Idles good too. One thing I did notice. It takes just a tad more spin of the starter to start the engine. But thats it.

if I figure out how to post a video I will show you guys the idle and engine sound.

Thanks yo everyone who tried to help and provided advice. 😀😀😀