1994 motor swap to 1998-2001 motor. NEED HELP!

Ok here goes it, I have a 1994 XJ five speed original motor developed horrible knock, so i swapped it out for a 1998 or 2001 4.0. It was setup for fuel injection, I removed all of the adapter and the fuel injection from that motor. I assembled all of my 94's Throttle body system also all of its electrical and vacuum sensors. The transmission is brand new with only about 800 to 1200 miles on it, it is not rebuilt new, not reconditioned, it was straight out of the craight brand new. All of that out of the way, It's been almost 2-2.5 years since that i have been chasing everything that i can think think of when i have time. I have replaced the timing sensor that mounts on the front top of the transmission and just behind the Flywheel. Now heres the problem it will not idle correctly, will not rev out above 3500 rpms, will not go above 35mph. Fuel pump is not bad the pressure is correct. PLEASE HELP ME I WANT MY CHEROKEE BACK, IF I CANT GET IT RUNNING I WILL BE FORCED TO SELL IT BY THE END OF THE YEAR. MUCH THANKS TO ALL.

ADrgnmn said:

Ok here goes it, I have a 1994 XJ five speed original motor developed horrible knock, so i swapped it out for a 1998 or 2001 4.0. It was setup for fuel injection, I removed all of the adapter and the fuel injection from that motor. I assembled all of my 94's Throttle body system also all of its electrical and vacuum sensors. The transmission is brand new with only about 800 to 1200 miles on it, it is not rebuilt new, not reconditioned, it was straight out of the craight brand new. All of that out of the way, It's been almost 2-2.5 years since that i have been chasing everything that i can think think of when i have time. I have replaced the timing sensor that mounts on the front top of the transmission and just behind the Flywheel. Now heres the problem it will not idle correctly, will not rev out above 3500 rpms, will not go above 35mph. Fuel pump is not bad the pressure is correct. PLEASE HELP ME I WANT MY CHEROKEE BACK, IF I CANT GET IT RUNNING I WILL BE FORCED TO SELL IT BY THE END OF THE YEAR. MUCH THANKS TO ALL.

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first, which one is it from, 98 or 2001? there are some differences that might determine what is wrong there...

Did you swap the flywheel from the 94 on to the new engine?

Not sure, but your old camshaft could be different from an 01, considering 01's had distributorless ignition (speculation).

Also, I believe on the newer engines (still more speculation, not always sure), the crank position sensor was on the front of the block...

I'm just trying to help out as much as I can... please someone come in and help! (5-90!)

2000-2001XJ had COP/DIS with the #0331 head - other models from 1999.

As I understand it, the distributor was reduced to an oil pump drive/camshaft position sensor head combination. You should be able to remove the drive assembly and drop in the distributor without much effort - but you'll have to make sure to time it properly.

You should also be able to use the older FI on the newer engine - unless you've already gone and swapped everything (a full system swap is a bigger pain than a full system installation. BTDT.)

When you say "won't idle correctly," what precisely is going on? "Won't idle correctly" is a pretty open field, and I'd like to see it narrowed down. Elsewise, we're just guessing here - I know I dislike having to guess, and I'm sure others dislike it as well. Using a shotgun to remove a tumour is ill-advised in any case...

If you can give with a better (more detailed) description of your symptoms, we can get a better picture of what is or isn't happening. Think of it like taking your child to the surgeon - you want to give him as much information as you can, no? Same principle applies.

Mr_Random said:

Did you swap the flywheel from the 94 on to the new engine?

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This question came up in another thread recently. The flywheel part numbers were the same, so no need to swap flywheels. I'm betting distributor needs to be properly timed.

the motor i had bought for the swap had a look alike distributor but no distributor cap it was grey in color thats as good as i can describe it. the idle problem is either no idle or it lopes like it has a massive cam, iam for sure it has no cam. i used every single piece of 1994 technology my original motor had, none from the motor i bought. let me know what you think and ill check in. thanks for the help.

i also used my 94's flywheel, motor bought for the swap was bolted to an automatic i removed all of that, i prefer stick shift.

Yes then take out your distributor and time it properly. Thats really whats pointing to your issue.

what piston is best to position at tdc and im taking a stab in the dark the distributor needs to on that same piston fire.

have you considered that the spark plug wiring might be off?

Yes i have, it is not off it is in correct order. What piston is best for setting the timing? I cannot just turn the distributor it is in a fixed position.

Im not sure on the newer DIS style engines, but 4.0's were keyed on the distributor. It IS still possible to stab it in incorrectly but you'll have to verify what I just said, Im not too sure, but it is an iddea.

would anybody know how iam going to know when my #1 piston is going to be TDC on its compression stroke?

ADrgnmn said:

would anybody know how iam going to know when my #1 piston is going to be TDC on its compression stroke?

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AD,
This writeup is what I used to install my distributor.

http://www.angelfire.com/my/fan/dist_index.html

In it Dr. Dino recommends removing the valve cover & watching the movements of the rocker arms. Not sure how else you'd tell what stroke it's on.

I suppose you could feel the air pressure at the spark plug hole since TDC on the exhaust stroke will have at least the exhaust open so no compression. Find the stroke with compression by having someone feel the compression in the hole or loosely screwing the spark plug in & listening for the escaping air while you turn the crank.

Another writeup on dist timing by the illustrious GoJeep.
http://www.go.jeep-xj.info/HowtoEngineInstall4.htm

Ok so i got the timing takin care of as far as i can tell by the sound of the motor and its idling now, it will idle just fine, then it will idle low and high i do not mean really high just like couple hundred rpms differnce.. I did notice that a vacuum line is cracked at the fitting, the fitting is fine, it is hose its self. It is the vacuum to the right of the throttle body if you stand driver side of the motor, it leads to the valve cover. my question is could the leak cause the motor to run like this?