ECU = Engine Control Unit. The issue being a 4.6 ECU would not effectively control a 4.0 block because it's expecting different timing (due to the longer stroke), fuel, and so on.

 

Thanks Dan. Is it then possible to swap the ECU among the comparable engine (4.0 ecu with 4L engine)? And if you do will transmission mount fine? Does rover use the same transmission Fromm 99 - 2004? Finally, as you suggested pinning might be the better option, but I am not fully confident on process, therefore prefer to get any experienced person to do it. Any suggestion for experienced mechanic? In advance, I appreciate the feedbacks

 

Reflash the ECu with a 4.0 .bin file. Other than that the O2 sensors will accommodate Air / fuel and the timing will be retarded if there is knock. You can use the Pro2DMEditor to remap the table. I'd just try it and see the results. Nothing to lose.

Press the liners to the register and buy the correct Cometic gasket. The fire ring does not sit on the liner and trap it properly. I'd bet that 99.9% of people never bother to accurately measure the OEM gasket fitment over the liner.

Good Luck

MAK

 

You can reset the ECU for either engine. If you try to swap out the ECU, you must also swap out the BCU from the same doner vehicle or it will not allow the engine to start.

 

If you're going to have the ECM re-programmed, you might as well have the BCU reprogrammed at the same time, so there would be no need to replace it. You'd actually be better off keeping your old BCU, and getting them correct ECM for the engine size you are installing. Then you don't have to worry about the odometer being different, your key-less entry, etc. and all you have to do is sync your ECM/BCU security code. Your VIN will be wrong in the ECM though.

Even with the Land Rover dealer's computer system, it would be difficult program a Bosch computer to a different engine size. It's not as easy as it is on a GEMs. The Land Rover system reads the computer that is there, and flashes it based on what it sees. In the case of a NEW computer you answer questions and type in the VIN number and correct values are loaded, so to change from 4.0 to 4.6 or back, you'd need the VIN of a discovery that has the same emissions equipment as your car, but a different size engine.

Here is some info from a very smart guy on the subject of land rover computer systems: VIN on motronic V8 D2 using nanocom - Australian Land Rover Owners

 

The timing should be the same, because they've made the compression ratio the same on the 4.0 and 4.6. As far as fuel goes, the computer seems to be able to keep up, which makes sense because the injectors, fuel pump, and just about every sensor, including the guts for the MAF and the o2, are the same for 4.0 and 4.6. The computers do have different programs, but most people report no issues running a 4.0 with a 4.6 computer or vice versa.

Except for the Australians. They complain about pinging when running a 4.6 in a disco. (all of their discos had 4.0 from the factory). Perhaps their stock fuel map is different than ours....

 

There is no need to reprogram a BCU when editing the fuel/timing tables on the ECU. There will be a checksum equivalent with Pro2DMEeditor. To much thought and to little experience from some of you guys.

The Bosch 5.2 ECU tables are no different to flash on a Disco than a Porshe.

www.thePro2DMEeditor.com - Motronic Map Editing System

We have been doing this for years on GM, Ford, and Dodge ECU's. Is this Disco to far advanced to modify for the general masses? I have to wonder considering I have already reflashed the 4.0 map table.

Go figure.

MAK

 

I didn't actually mean reprogram it. I just meant that if you are going to have the dealer hook up to reflash the ECM there isn't much difference to talk have to store the security key from the BCU at the same time. No need to repace everything if you've got access to the good computers.

 

I have read somewhere that the air intake that the MAF is on is slightly larger in the 4.6 engines. This may or may not matter...

As for the dropped sleeves discussion. I don't think they can "drop" because of the lip in the block, in the bottom of ech cylinder, that the sleeves are pressed against. However it is my understanding that the top of the sleeve does not rest against the head, meaning that they can come loose and move up and smack against the mating surface of the head, THEN they can drop back down to the lip, and back up again and so forth as the piston moves up and down inside the sleeve, the sleeve moves ever so slightly up and down inside the cylinder. I have read on here that it's really not that big a deal and you can drive the truck forever with this happening. The only real problem that arises is a ring worn into the mating surface of the head where the sleeve has been smacking against it, but it would take several hundred thousand miles for the ring to get bad enough to cause a problem, and these aren't Japanese or German engines, so the most you can really expect to get out of these engines are about 250,000. Maybe a little more, but not much. If you made it to 375,000 or 425,000 then it may get bad enough to cause a problem with the head. Thats the opinion I formed when I researched this matter for myself, and I stopped being worried about it. A "dropped sleeve" is just a saying. It doesn't really portray what actually happens very well. A "slipping sleeve" would be more appropriate.

 

As usual, thanks for filling the gaps in my general mechanical knowledge with LR specifics!