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-   -   California 4.0 OBDII Swap (http://www.jeepforum.com/forum/f8/california-4-0-obdii-swap-1530716/)

SLO_Ken 05-31-2013 05:40 PM

California 4.0 OBDII Swap
 
I'm currently swapping a 4.0 from a '98 XJ into my '86 CJ. Immediately before this, I had the original 258 with a Howell TBI that had already been bored .060 over, and had started blowing oil. I figured I could either get a reman long block from ATK or S&J (~$1500), or find a wrecked XJ/TJ and pull the engine from that.

I found an engine from a '98 XJ not far from me and the price was right, so I went and picked it up. Most of the write-up's I've seen regarding doing a 4.0 swap are directed toward the OBDI system that was produced '91-'95. OBDII is the more current system that was around from '96 to '01 or so.

Mechanically, there is little to no difference between the two. Pretty much all the differences are in the sensors and communications protocol.

As of now, I've competed the physical swapping of the engines. That is to say, I've pulled my 258 out, and got the 4.0 bolted up to the frame and transmission. That was pretty straightforward. There were only a couple things that needed to be addressed, and these are common to all 4.0 swaps (as far as I can tell).

First, the pilot bushing from the 258 doesn't fit in the 4.0. I had read in several places that the recess in the 4.0 crank would be unfinished, and I'd have to measure the actual dimension and machine the bushing to fit. Well, my 4.0 had a finished bore, and it was 1.000". I had bought a couple stock 258 pilot bushings from RockAuto for ~$4 ea, so I took one and turned it down on a lathe to fit. Slid right in.

Second, I had to add a hole and make a bracket for the Crank Position Sensor on the bellhousing. I simply followed instructions found here and here. Again, this is common to the OBDI and OBDII setups.

Third, the motor mounts from the 258 bolt right up to the 4.0. There is one bolt that is not like the others... The rear-most bolt on the drivers side of the block is M12 thread, not 3/8-16 like the others. This requires drilling out the bracket a little.

So, I've addressed these details and have bolted the engine in place. Very straight forward. Now on to the wiring and emissions equipment.

This is where the OBDII is different. Being that I want to continue to register this Jeep in California, I need to bring over all the emissions equipment from the '98. This includes the Cat (with O2 sensors up and down-stream), evap canister, evap purge solenoid, leak detection pump, CEL, and diagnostic port. I haven't actually completed this part yet, but I'll be sure to post updates and questions as I go.

Skerr 05-31-2013 09:02 PM

I am also in the middle of this swap. We are using a 4.0 from a '97 XJ, going into a '79 CJ5. I was told that the OBDII ECM will require the factory key with the chip, or the security system built into the ECM will not allow the engine to run. It will start, then die. You sound much more confident than I! I swapped the harness and all of the sensors to OBDI (JY acquisition). We are finishing up the mod to the 258 bellhousing for the CPS. Replaced the rear freeze plugs today. The motor mount bolts need to be shorter, as the 258 mounts are thinner, and our bolts bottom out. It looks like the T18 pilot bushing will work with the 4.0 with no modding... as I understand it from Novak. I would REALLY APPRECIATE any tips on the "5 wires to fire", CJ wires used, etc. Subscribed. Thanks... and good timing! :D

SLO_Ken 05-31-2013 11:09 PM

The security key is news to me. I suspect that the security module is independent of the ECM, but communicates with it via the CAN Bus. So, if the security system was disarmed before the ECM was removed from the donor, it should be good, I hope?? :confused:

If not, I'm pretty sure I can find and use an ECM from a '98 Wrangler Sport, which I believe did not have have integrated security...

Skerr 06-01-2013 12:08 AM

I'm not sure about all of it. I have read so many threads that my brain is floating! I know somebody was commenting on the SKIM (embedded security in the ECM), but that is Greek to me! You should probably do some investigating about it. I am also told that my auto tranny ECM won't work with the manual in the CJ, or that it will cause some issues, and that I should seek out an ECM from a manual XJ. But that is as scarce as snow around here! I am VERY interested in your steps.

We are also making the CPS bracket according to Kman from your first link. I spoke with Eric at Novak earlier this week about the gap between the flywheel and the sensor. He said to use a piece of cardboard from a cereal box to set it. I figure you have already conquered that since your engine is installed. What did you do for your gap?

SLO_Ken 06-01-2013 12:20 AM

I can help out on the CJ side for the 5 wires to fire:

Batt(+); This is the red wire that would have been attached to the battery side of the CJ starter solenoid. Position EY on the firewall connector. There should be a fusible link or fuse between the firewall and the battery. You'll want to splice your OBD harness into the protected side of this wire.

Ground [Batt (-)]; Blk. Make sure you have a good connection from wherever you connect your OBD harness ground to Batt(-).

Start; This would have been the "S" terminal of the CJ starter solenoid. Position AX on the firewall connector. Also, the smaller of the two power wires at the Duraspark ignition module. Lt Blu.

Ign Feed; Position BW on the firewall connector. The larger of the two wires at the Duraspark ICM. Red with Wht trace.

Run; This is only hot in "run," not "start" or "acc." It is position CZ on the firewall connector. It feeds the Reverse lights switch on the transmission. Red.

Skerr 06-01-2013 12:26 AM

Thanks, Ken. I need to get into my Chiltons and look for the connector pinout. You simply use the wires from the OBD harness and splice them into the bulkhead connector at those positions??

SLO_Ken 06-01-2013 12:33 AM

Quote:

Originally Posted by Skerr (Post 15505625)
I'm not sure about all of it. I have read so many threads that my brain is floating! I know somebody was commenting on the SKIM (embedded security in the ECM), but that is Greek to me! You should probably do some investigating about it. I am also told that my auto tranny ECM won't work with the manual in the CJ, or that it will cause some issues, and that I should seek out an ECM from a manual XJ. But that is as scarce as snow around here! I am VERY interested in your steps.

We are also making the CPS bracket according to Kman from your first link. I spoke with Eric at Novak earlier this week about the gap between the flywheel and the sensor. He said to use a piece of cardboard from a cereal box to set it. I figure you have already conquered that since your engine is installed. What did you do for your gap?

For the OBDII, the only difference I could find between the ECM for the auto vs manual is in the wiring diagram. For the auto, there is provision for a neutral safety switch. For the manual, that terminal is grounded. I hope there is no differences in the ECM programing.

For CPS spacing, I did exactly that. I assembled the bellhousing to the motor while it was on a stand. On my bracket, I made it fit tight to the belhousing bolts, but the CPS could float on the bracket a little for adjustment. That is, the mounting holes on the CPS are about 1/4", but I used 10-32 screws to attach it to the bracket, so there is some wiggle room for adjustment. I installed the bracket to the bellhousing, then taped a piece of cardboard from a cereal box to the CPS and mounted it to the bracket such that the cardboard was touching the flywheel. When I took it apart, I did not remove the CPS from the bracket, just removed the bracket from the bellhousing.

http://imageshack.us/a/img23/4564/img1778kp.jpg

Skerr 06-01-2013 12:38 AM

Smart idea on the CPS bracket! I definitely want to be able to change it without dropping the tranny.

Have you addressed the vehicle speed sensor? Not sure it is applicable to every tranny combo, but it is, apparently, for our T18. Where did you get yours, and what did you use for an adapter?

SLO_Ken 06-01-2013 12:40 AM

Quote:

Originally Posted by Skerr (Post 15505647)
Thanks, Ken. I need to get into my Chiltons and look for the connector pinout. You simply use the wires from the OBD harness and splice them into the bulkhead connector at those positions??

Sorry, the bulkhead connector positions I gave are for the '84-'86 CJ's. You'll have to verify where they are on your application.

As for splicing, I think it will be easier to splice into the wire a little ways away from the connector. I'll try to remember to take some pics when I tackle this next week...

Skerr 06-01-2013 12:45 AM

Quote:

Originally Posted by SLO_Ken (Post 15505659)
Sorry, the bulkhead connector positions I gave are for the '84-'86 CJ's. You'll have to verify where they are on your application.

As for splicing, I think it will be easier to splice into the wire a little ways away from the connector. I'll try to remember to take some pics when I tackle this next week...

Geeeeez... I'll be racing home from work to check your thread!! Thanks for the tips. Gotta hit the sack.

SLO_Ken 06-01-2013 12:45 AM

Quote:

Originally Posted by Skerr (Post 15505657)
Smart idea on the CPS bracket! I definitely want to be able to change it without dropping the tranny.

Have you addressed the vehicle speed sensor? Not sure it is applicable to every tranny combo, but it is, apparently, for our T18. Where did you get yours, and what did you use for an adapter?

Haven't got to the VSS yet. I understand the sensor from a '88-'93 Dodge Dakota will work.
http://i.ebayimg.com/t/Duralast-Well..._id=89040003C1

Not sure what I'm going to do for an adapter yet. Supposedly the required adapter can be found on the cruise control module under the dash of 90's XJ's.

Skerr 06-01-2013 07:16 AM

We did some Dakota diving a couple weeks ago. It will be more daunting than I first expected. Vehicles sit low to the ground/mud/weeds/fire ants, etc. We couldn't find a VSS, and I was PMed by one of your Cali Jeep brothers who has everything for sale, reasonable. I hope he still has it because I haven't gotten off my butt to send him a check! The same issue exists for the adapter. We just don't have the junk resource in this area. I'm wondering if you can't find it at a hardware store?? Worse-case scenario we buy it from Hesco.

The JY did net the Neon injectors for the 4.0 upgrade and an OBDI fuel rail... so it was a good trip.

CSP 06-01-2013 07:49 AM

I don't know this for a fact, but I don't believe that all of the ECMs contain the SKIM module/programming. They are commonly found in the Grand Cherokees, but I don't know that the XJ ECMs had that feature in all vehicles made.

Nice work documenting this!

Skerr 06-01-2013 02:17 PM

Quote:

Originally Posted by CSP (Post 15506085)
I don't know this for a fact, but I don't believe that all of the ECMs contain the SKIM module/programming. They are commonly found in the Grand Cherokees, but I don't know that the XJ ECMs had that feature in all vehicles made.

Nice work documenting this!

I don't know either. With all that's out there I haven't found anything that leaves me with definite knowledge. But then I am only just breaking into the electronic automotive world! Things like motor mounts, bolt sizes, cooling, etc, is well explained. But to a novice, like myself, it creates more questions and some confusion. I am also documenting this on Clay's Build Thread, but not as far as Ken.

SLO_Ken 06-02-2013 10:24 AM

I dove into the XJ wiring diagrams yesterday, trying to figure out where the "5 wires to fire" need to splice into the OBDII harness. As far as I can tell, only 4 of the 5 wires are required. The "run" wire described above (corresponds to the ballast resistor / fuel pump wires shown here) is not used for the OBDII system.

So, my "4 wires to fire" are:
CJ -> XJ
Batt(+) (Red) -> Batt Feed (Red/Bk)
Ground -> Ground
Start (Lt Bl) -> Start (Ylw)
Ign Feed (Red/Wt) -> Ign feed (Bl/Wt)

edit: the 5th wire is
Ign Feed (Red/Wt) -> Ign feed (wht)


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