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4.0 OBDII swap
Posted: January 18th, 2012, 8:05 pm
by 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?
Re: 4.0 OBDII swap
Posted: January 18th, 2012, 9:15 pm
by 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
Re: 4.0 OBDII swap
Posted: January 18th, 2012, 9:18 pm
by 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.
Re: 4.0 OBDII swap
Posted: January 18th, 2012, 10:31 pm
by 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.
Re: 4.0 OBDII swap
Posted: January 19th, 2012, 4:44 pm
by SilverXJ
Resistors won't work on the O2 sensor signal to PCM. They might work on the heater element circuit though.
Re: 4.0 OBDII swap
Posted: January 19th, 2012, 7:33 pm
by 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.
Re: 4.0 OBDII swap
Posted: January 19th, 2012, 9:12 pm
by SilverXJ
jeepthrills wrote: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
Re: 4.0 OBDII swap
Posted: January 21st, 2012, 5:25 pm
by jeepthrills
interesting...Sim may be the way to go here.Thanks!
Re: 4.0 OBDII swap
Posted: January 21st, 2012, 7:53 pm
by 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.
Re: 4.0 OBDII swap
Posted: January 30th, 2012, 9:45 am
by jeepthrills
good infor thanks1
What about pilot bushings? Hesco for 114 dollars
any other alternatives?
Re: 4.0 OBDII swap
Posted: February 13th, 2012, 9:22 pm
by 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.
Re: 4.0 OBDII swap
Posted: August 18th, 2012, 12:24 pm
by 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.