I've got a 96 xj with a tired 2.5l motor. According to the FAQ it should have the ax-15. My dad has a much lower mileage '99 4.0 engine with the complete engine harness and computer. So what all would be needed to complete the swap. I searched but couldn't find anything. I would like to be able to tow a boat or camper and not be so slow. Thanks
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2.5l to 4.0 swap
- Thread starter 962door
- Start date
- Location
- Rainy side of Washington
At the very least - motor, all accessories, engine compartment wiring harness from a '96 and engine computer from a '96, motor mounts, etc. Radiator probably. You won't be able to use the '99 computer and harness without adapting them to work with all the emissions junk and stuff from a '99, and also the interior wiring harness and dash harness. Unless you've got both FSMs, some electrical expertise, and a lot of patience, it's not going to end well - you'll need a dash cluster and other stuff from the '99 also, it will really be easier to find a '96 6cyl engine harness/sensors/computer as '96 was the most-produced year for the XJ and the 6cyl engine was the most common.
You will also need the flywheel, possibly clutch and associated parts, and clutch housing (bellhousing) from a '96 or similar years with the 4.0 and AX-15.
So, to clarify, parts list:
* bellhousing and clutch, clutch housing spacer (the aluminum sheet that covers the open end of the bellhousing) from a '96 or similar years 4.0L/AX-15 equipped XJ
* '96 engine wiring harness, engine compartment wiring harness, sensors, etc etc
* '96 ECU from a 4.0L, either AX-15 or AW-4, will be easier with one from an AX-15 equipped donor though
* radiator for a '96 4.0L
* throttle body from a '96 4.0L?
* motor mounts and possibly brackets from 4.0L
I think the exhaust manifolds and such should just bolt up, and the 99 intake manifold will give you a few more HP supposedly, you'll need a '96 down throttle body for it *I believe* so that the '96 wiring harness will plug into the sensors, though you can probably splice wires without issue to make the '99 throttle body and sensors work.
You will also need the flywheel, possibly clutch and associated parts, and clutch housing (bellhousing) from a '96 or similar years with the 4.0 and AX-15.
So, to clarify, parts list:
* bellhousing and clutch, clutch housing spacer (the aluminum sheet that covers the open end of the bellhousing) from a '96 or similar years 4.0L/AX-15 equipped XJ
* '96 engine wiring harness, engine compartment wiring harness, sensors, etc etc
* '96 ECU from a 4.0L, either AX-15 or AW-4, will be easier with one from an AX-15 equipped donor though
* radiator for a '96 4.0L
* throttle body from a '96 4.0L?
* motor mounts and possibly brackets from 4.0L
I think the exhaust manifolds and such should just bolt up, and the 99 intake manifold will give you a few more HP supposedly, you'll need a '96 down throttle body for it *I believe* so that the '96 wiring harness will plug into the sensors, though you can probably splice wires without issue to make the '99 throttle body and sensors work.
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