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Engine Swap

P

play_in_the_mud

NAXJA Forum User
Location
delaware
Went to pickup the an 89 in great shape for a good price, price was too good, it has a nice knock in the engine. Getting a 91 with a good engine for free b/c of the very shifted unibody. Putting the engine from the 91 in the 89. Was told by a service guy at the jeep dealer that everything would bolt up fine, should take the distributor, rail and injectors from the 89 and put on the 91 thats the only things he said to do. Any input on anything that should be replaced/checked out/adjusted while the engine is outta the jeep?? Thanks for any help
 
Put a new high volume oil pump and water pump on the 89, clean it up and fix any leaks. Check your CPS sensor before you fire it up. :repair: You are looking at about 30 hrs labor at least. Good luck!!
 
dont know how i didnt think to replace water pump and oil pump. prolly gonna do all the hoses that i can find. did forget to say i am seriosuly considering taking the trans, transfer case and a few other goodies outta the 91 as well, almost 100,000 less miles on them.
 
You will need to extend the EGR tube between intake and exhaust slightly to fit the newer style head. (and grind a little to fit the intake) Some of the Stroker list people are just swapping the sensors and throttle body to the HO intake, but w/o the EGR valve, you have no way of getting rid of ping (You also need to thread the hole for the knock sensor on the driver's side of the block. MUCH easier to do with the motor out!)
Just a FYI, if you have what feels like a low powered Renix ('87 to 08/90) 4.0L that has internal noises, unplug the knock sensor to see if the power MAJORLY picks up. The lifter clack or piston slap noises can confuse the piezo electric sensor (which is a fancy name for microphone) into thinking the motor is pinging and retard timing. I added a variable resistor to my old one that I could adjust on the fly (inline with the sensor) when I heard any ping.
 
carnuck said:
You will need to extend the EGR tube between intake and exhaust slightly to fit the newer style head. (and grind a little to fit the intake) Some of the Stroker list people are just swapping the sensors and throttle body to the HO intake, but w/o the EGR valve, you have no way of getting rid of ping (You also need to thread the hole for the knock sensor on the driver's side of the block. MUCH easier to do with the motor out!)
Just a FYI, if you have what feels like a low powered Renix ('87 to 08/90) 4.0L that has internal noises, unplug the knock sensor to see if the power MAJORLY picks up. The lifter clack or piston slap noises can confuse the piezo electric sensor (which is a fancy name for microphone) into thinking the motor is pinging and retard timing. I added a variable resistor to my old one that I could adjust on the fly (inline with the sensor) when I heard any ping.
Click to expand...
a little more info on this knock sensor, what does it look like? I see that you say it is located on the drivers side. And if I run premium fuel(Always run 92 octane) is the knock sensor needed?
If so, how did you design the variable resistor and set it up to use in cab? thanks, xjoe
 
The knock sensor is screwed into the block (where 1 of the full size Jeep motor mounts goes, which is how/why I know) right behind the motor mount. IIRC, it's 15mm 1.25 pitch (I have the tap someplace here, but I'm too busy to dig it up)
It looks like a oil pressure sending unit almost (a very skinny one) Even with 92 octane, it may ping (depends more on combustion temps) If you are running the Renix system, it's already wired in. Would be nice to add to the HO system retroactively as many ping on lower/cheaper gas. The factory/dealer fix is to reflash the HO's map to get away from the ping.
The switch I have is just a basic resistor wired dial I pulled out of some electronic stuff I used to have. It's probably a volume dial from a crytal radio set I used to have.
 
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