4.0 OBDII swap

[jeepthrills]

so before I stroke the 4.0L...I thought I would first get the wiring in and make it a runner...that way I will not have any compounded issues.

So since I dont have emisssions to deal with and will not be installing a Cat, would it be better to omit the downstream O2 sensor and replace it with a resistor? Or will it still be required for proper mixture?

I am still in the begining stages, the 4.0L was just pulled and I am working on yanking the XJ fuel line, fuel pump, harness, etc.. and waiting on my FSM to show up to figure the 2 bundles of wires which pass through the firewall.

Also which pilot bearing/bushing for CJ manual tranny?

[604rail_king]

ive used Jpipes in the past for dealing with the rear o2 when deleting the cat.

http://vibrantperformance.com/catalog/p ... ucts_id=70

[jeepthrills]

is the sensor required to keep the engine running in proper trim? I thought I could just toss a resistor and be done with it.

[604rail_king]

the rear o2 is basically a cat check. if the cat is present the rear o2 will get a different reading than the front o2 and should function as normal. without the cat you will get a o2/cat related CEL... resistors have been used in the past however im not a fan of them. a Jpipe is much simpler and unlikely to fail imo.

[SilverXJ]

Resistors won't work on the O2 sensor signal to PCM. They might work on the heater element circuit though.

[jeepthrills]

So I still must use the rear O2? CRAP! ok..looks like the J-pipe is added to the parts list then.

What is the general opinion on fuel pumps? I just cannot justify the noise of an external. So my plan is make a Franken-Pump using my CJ 21 gallon sender with the XJ's pump affixed in some way to be determined later.

[SilverXJ]

So I still must use the rear O2? CRAP! ok..looks like the J-pipe is added to the parts list then.

You can use SIMs. I have heard ones from www.montanafab.com work

This is also interesting: http://www.bigdaddiesgarage.com/mini-cat-cel-fix.html

[jeepthrills]

interesting...Sim may be the way to go here.Thanks!

[SilverXJ]

It definitely is. I'm running two Casper sims that have been working well for several years. The feds forced them to stop making them though.

[jeepthrills]

good infor thanks1

What about pilot bushings? Hesco for 114 dollars

any other alternatives?

[Landon]

I just ordered a pilot bushing from Novak. $28, shipping included. That's for my T18, yours may be less.

I'm like you, going to get the 4.0 in first, the mechanical stuff is easy. After reading horror stories about Chrysler PCMs and experiencing a $1K trip to the dealer for one for our Caravan, I'm going to try a carb before trying to get OBDII straightened out. But please keep posting what you learn.

I got a 4.0 with some of the wiring and intake/exhaust manifolds, flywheel, and sensors this weekend. 120K on the clock. Looks clean.
Now I need to decide what clutch to get, I expect it's the one for my J10, to match the bellhousing.

[DirtyB]

I'm searching for a donor vehicle now for the 4.0 FI head swap now. I did a swap already with a '94 grand cherokee OBDI system on my '81 CJ. I'd like to do the same on my '84 CJ, but I'm scared about the OBD II set up. Is it really complicated. I don't need a check engine light to pass my emissions testing.