4.0 HO conversion and transmission questions

dj69firebird69 · 01-10-2010, 05:02 PM

Thanks GPER for the CJ link, there is a lot of good information in there which is exactly what I have been looking for.

dj69firebird69 · 01-10-2010, 05:09 PM

Its definately going to be worth doing this and I am trying to stay hard on this project so it doesn't turn into a five year project. I know that it won't be cheap but to get it running good with the old 258 would have cost a bunch of money too and now i have a XJ to part out when I'm done and some stuff to sell from the YJ so I won't be in too deep.

jmb8813 · 01-10-2010, 05:46 PM

why cant anyone answer the questions on here and deal with what people are working with.....the question wasnt should i waste my time on the xj

GPER · 01-10-2010, 06:25 PM

For what it is worth my 31 year old CJ had to be towed home once. While my 16 year old XJ with the 4.0 has been towed twice in the couple of years I used it for a DD.

My CJ doesn't have all the electronic crap to go out. My next CJ motor will be a 258 with the 4.0 head, Crane torquer cam, Clifford intake for the 4.0 head to fit a Motorcraft 2100, CDI, Team Rush upgrade and the 4.0 exhaust manifold

kyrel69 · 01-12-2010, 08:22 AM

well if you are going to use the computer out of the XJ then it will be easyer to use the tranny to, b/c if you do not you will either have to get another computer or get yours reflashed. The computer in XJ are hooked up to the auto tranny. Also the tranny in the XJ have a overdrive so it will make your YJ a better DD.

dj69firebird69 · 03-28-2010, 09:40 PM

Many people didn't suggest it, thought i couldn't do it, or told me I should fix the XJ rather than the YJ. Well I did it with almost no help from anybody. I ended up parting out my XJ, making enough to cover this project completely. I bought a 92 YJ Motor, Trans, T-Case, Computer, and Wiring Harness, dropped it in the YJ without a problem. Spent many nights trying to figure out wiring and at last I got it to turn over. Now it is running but still needs some things finished and the doghouse put back on. This is the best upgrade that this jeep has ever had and I am glad that I continued on with this project even after being told by many people that it was a bad idea. If anyone is trying to do a 4.0 swap I may be able to help some and don't listen to people who have never done it before because they do not know what they are talking about.

mckeddie · 03-28-2010, 10:31 PM

you can run the xj computer with a yj tranny fine. i ran an xj computer in my yj for about 200,000 miles after i accidentally put a hole saw through the original computer in it. pulled the computer out of a buddy's xj, and actually it ran better than it ever had before (91 yj, with the 4.0l out of a 2001 tj, with a 94 xj computer).

greg

03-28-2010, 10:31 PM	#7
mckeddie Join Date: Apr 2007 Location: van wert oh Posts: 583	you can run the xj computer with a yj tranny fine. i ran an xj computer in my yj for about 200,000 miles after i accidentally put a hole saw through the original computer in it. pulled the computer out of a buddy's xj, and actually it ran better than it ever had before (91 yj, with the 4.0l out of a 2001 tj, with a 94 xj computer). greg __________________ zuk buggy.....it'll be a jeep eventually.

01-10-2010, 05:02 PM	#1
dj69firebird69 Join Date: Dec 2009 Posts: 15	Thanks GPER for the CJ link, there is a lot of good information in there which is exactly what I have been looking for.

01-10-2010, 05:09 PM	#2
dj69firebird69 Join Date: Dec 2009 Posts: 15	Its definately going to be worth doing this and I am trying to stay hard on this project so it doesn't turn into a five year project. I know that it won't be cheap but to get it running good with the old 258 would have cost a bunch of money too and now i have a XJ to part out when I'm done and some stuff to sell from the YJ so I won't be in too deep.

01-10-2010, 05:46 PM	#3
jmb8813 01 jeep tj Join Date: May 2009 Location: the city that offers nothing Posts: 153	why cant anyone answer the questions on here and deal with what people are working with.....the question wasnt should i waste my time on the xj

01-10-2010, 06:25 PM	#4
GPER Join Date: Feb 2007 Location: Kettering, Ohio Posts: 811	For what it is worth my 31 year old CJ had to be towed home once. While my 16 year old XJ with the 4.0 has been towed twice in the couple of years I used it for a DD. My CJ doesn't have all the electronic crap to go out. My next CJ motor will be a 258 with the 4.0 head, Crane torquer cam, Clifford intake for the 4.0 head to fit a Motorcraft 2100, CDI, Team Rush upgrade and the 4.0 exhaust manifold

01-12-2010, 08:22 AM	#5
kyrel69 Join Date: Jan 2007 Location: Middletown, Ohio Posts: 372	well if you are going to use the computer out of the XJ then it will be easyer to use the tranny to, b/c if you do not you will either have to get another computer or get yours reflashed. The computer in XJ are hooked up to the auto tranny. Also the tranny in the XJ have a overdrive so it will make your YJ a better DD.

03-28-2010, 09:40 PM	#6
dj69firebird69 Join Date: Dec 2009 Posts: 15	Many people didn't suggest it, thought i couldn't do it, or told me I should fix the XJ rather than the YJ. Well I did it with almost no help from anybody. I ended up parting out my XJ, making enough to cover this project completely. I bought a 92 YJ Motor, Trans, T-Case, Computer, and Wiring Harness, dropped it in the YJ without a problem. Spent many nights trying to figure out wiring and at last I got it to turn over. Now it is running but still needs some things finished and the doghouse put back on. This is the best upgrade that this jeep has ever had and I am glad that I continued on with this project even after being told by many people that it was a bad idea. If anyone is trying to do a 4.0 swap I may be able to help some and don't listen to people who have never done it before because they do not know what they are talking about.