4.0 xj into a 2.5 MJ both 89's

rockwerks · Aug 19, 2003

Its funny I have a low mile 89 xj with 4.0 aw4 and 242 that I can't sell but many wrangler guys want my 2.5 TBI out of my MJ..so Im wondering what to look out for in the swap?

I know the fuel pump is different, motor mounts, etc. but will I have to change over wiring harnesses, or should the MJ already have the same harness in place.

and what else am I missing?

Eagle · Aug 19, 2003

The '89 2.5L is a TBI Renix system, so there are some differences in the underhood harness -- you're only firing one injector rather than 6. Don't know how different, or if there is a connector where you can make the change. I'll be doing the same thing soon, except mine's an '88 so I plan to just unplug the C101 connector on the firewall and drop in the injection harness for the 4.0L. Unless yours is a very early '89, you won't have a C101 connector.

CheapXJ · Aug 19, 2003

Eagle said:
I'll be doing the same thing soon, except mine's an '88 so I plan to just unplug the C101 connector on the firewall and drop in the injection harness for the 4.0L.

That's possible? that'll actually work?!?

Oh, Brian... I'm currently about halfway through this particular swap (just came in to take a drink break actually

) so I'll let ya know if I run into any weird problems.

rockwerks · Aug 19, 2003

KOOL! this truck cant be down long its what I haul my water in!

rockwerks · Aug 19, 2003

C101 connector on the firewall and drop in the injection harness for the 4.0L. Unless yours is a very early '89, you won't have a C101 connector.

HMMM..so where is this C101 connector my book dont show it.

CheapXJ · Aug 20, 2003

C101 is right above the brake booster. it's a HUGE connector

Eagle · Aug 20, 2003

They eliminated the C101 connector in mid-year 1989. I had always thought it was for everything under the hood, but in a recent perusal of the 1988 factory wiring manual (for an unrelated issue) I saw that it is labelled as "Injection Connector"

My next step, when I finish the current project, will be to compare the 4-cyl and 6-cyl schematics for the dashboard side of the C101 to verify whether or not I can just swap it from C101 out to the engine.

CheapXJ · Aug 21, 2003

Eagle said:
They eliminated the C101 connector in mid-year 1989. I had always thought it was for everything under the hood, but in a recent perusal of the 1988 factory wiring manual (for an unrelated issue) I saw that it is labelled as "Injection Connector"

My next step, when I finish the current project, will be to compare the 4-cyl and 6-cyl schematics for the dashboard side of the C101 to verify whether or not I can just swap it from C101 out to the engine.

I can assure you that it's NOT for everything under the hood. in fact, it ONLY connects to the injectors, CPS, TPS, IAC, temp sensor, knock sensor and O2 sensor.

4.0 xj into a 2.5 MJ both 89's

rockwerks

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