2.5tdi > 4.0 swap. questions on PCM and obd - JeepForum.com

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post #1 of 3 Old 04-02-2013, 06:37 AM Thread Starter
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1996 ZJ 
Join Date: Mar 2013
Location: Estonia
Posts: 7
2.5tdi > 4.0 swap. questions on PCM and obd


I have researched some more after posting my last topic and so far i have verified that the ax-15s bellhousing is indeed a 4.0 boltpattern and i belive getting the engine in the bay wont be anything hard. I know that the powertrain control unit has to be swapped out for it to work at all. but as it is the first car that has any kind of electronic drivetrain controllers in it i'm going to mod, i don't really know how those things work. so my question is what does the PCM actually contol besides obiousely the engine and the (automatic) tranny? also are there any other controllers i should know about when doing this?

Also, I belive the 96 diesel i have should be OBDII (need to verify it). But as i would need to swap out almost if not all the electronics concerning drivetrain control, would it be possible to to get an OBDI donor car?

You might ask why not just build it on a genuine 4.0? I think it will be easier to do it in the diesel as the cluch pedal assembly, tranny mounts and stuff like the driveshafts are already set up in there.

So far my mind is firmly set on doing the swap, but before i start looking for a donor car to get the engine and electronics, i'd like to determine if i am at all up to the task.

Any input would be greatly appreciated, even if negative. Please help a guy learn his Jeep stuff

Bought it, drove it, broke it, fixed it, drove it, broke it again... Love it!
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post #2 of 3 Old 04-02-2013, 02:43 PM
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1997 ZJ 
Join Date: Dec 2006
Posts: 19,793
going from the tdi to 4.0?
total fuel system, all firewall forward wiring.
ecu must be obdii unless you really want to change out the entire interior including all wiring, control modules and gauge cluster(and also the full hvac unit) almost nothing about the grand transferred from obdi to obdii except the shell, suspension, and long blocks on the motors.

it would be far simpler to build a manual swap on a 4.0. especially since you have such ready access to the clutch pedal assemblies from the tdi's in europe.

'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

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post #3 of 3 Old 04-03-2013, 02:13 AM Thread Starter
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1996 ZJ 
Join Date: Mar 2013
Location: Estonia
Posts: 7
Thank you for your reply

that's the info i was looking for about the OBDs. thought so myself, but wanted to be sure.

Now that you mention it like that it it does sound easier that way around. but there are some other pro's to the tdi > 4.0 swap tho. for instance there is an error in the system here, so when you modify your car and get it reregistered, for the insurance companys the engine outhput and other info stays unchanged. so i would be paying for 85kw of the diesel instead of the 4.0s ~140kw. that would make my insurance bills only half of what they really should be.

besides I would hate to scrap the diesel's body after the swap, because it is in a rather good shape(never been in sea water and such, very little rust). no one to sell to either...

Referring to my '98 ZJ interactive oem service manual, the 4.0 have bolt-on engine pads on the frame. can anyone confirm this? any measurements as to where the 4.0's engine pads(sorry if the word is wrong) would sit on the frame in a genuine 4.0?

Sorry, if all these questions are seemingly dumb. All part of the learning proccess

Bought it, drove it, broke it, fixed it, drove it, broke it again... Love it!
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2.5 , 4.0 , 5spd , diesel , swap

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