We're swapping out our 4.0L in our '02 D2 with a 4.6L from a '03. I'm reasonably sure it'll run with the 4.0 mapping in the ECU, but should I install the 4.6 ECU from the parts truck? Of course, it'll have to be re-programmed with the VIN I suppose. Any experience here?

 

I'm running a 4.6 in our 1999 d2. The 4.6 has less than 90k. The 4.0 it replaced had over 240k. We kept the 4.0 timing chain housing/oil pump. Runs like a sports car compared to the 4.0 per my better half who drives like she stole it. No issues with the 4.0 ECU.

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You will need to swap in both the ecu, but, and if you don't have a nanocom and you don't want the odometer to flash then the IC. But given the actual truck mileage is 240 you probably need a nanocom. You will need to sync the IDM to the new bcu/ecu combo. You should also swap the intake tube and airbox lid.

 

The 4.6 had the usual cracked intake/air box part (s) so we kept everything 4.0 externally.

Slightly better mpg. Hills that she couldn't maintain 70mph on she can now push 75.

Sitting on 285/70/16s with 3 inches of lift.




I do have the the entire 03 for spares but the 99 runs so well I don't see any need to swap anything further until something fails.

 

Can you elaborate? IDK what IC and IDM mean!

 

If you're not sure what those are I would leave it alone. Run the 4.6 on all 4.0 software/hardware. You won't maximize all the power potential she has but it's still going to be more power than your current 4.0...based on personal experience

 

instrument cluster and the IDM is part of the interior fusebox.

 

OK, I'm leaving it, to simplify my life.

IDM is apparently "Intelligent Driver Module". Part of the interior fuse box. One more nugget for my ever-increasing knowledge of the D2!

 

I don't drive the disco other than an occasional test run for diagnostics or after the repairs so I have to go off of second hand reports.

Our 4.6 is kind of a hybrid motor. It came to us as "timing jumped" but timing doesn't exactly jump on these, especially at sub 85,000 miles.

The oil pump gear ate through the timing chain cover, common issue m

Her 4.0 with other 240k had a slipped sleeve. Can be driven years like this but she is embarrassed at traffic lights and drives thru windows when people hear her "knocking"

I tore the engine down to the block. I pinned all the sleeves. I installed all new bearings/piston rings and put the 4.6 rotating assembly and cam in the 4.0 block. Low mile parts for free so why not upgrade?

I used the 4.0 timing chain cover, new timing chain and new oil pump.

Fast-forward a few weeks and she's loved the engine. She's getting more power and fuel economy on 285 70 17 mud terrains, steel bumpers and full size spare. She drives the dumb thing like she stole it....and gets free repairs. Unfortunately we start having some issues with leaks. First mod are plastic to metal coolant connectors/reservoir. Leak free for a few weeks. Then she starts pumping coolant out the overflow the moment it gets warm. I think back now, if the two heater cores I replaced over the last year were blown out due to a build up of coolant pressure before I did the engine work. The blocks behind the liners of these motors for worse as production went on.

Unfortunately my other spare 4.0 block from a 2001, while running when removed was no good. Tear down revealed a rodent nest under the intake manifold and they rotted/ate the valley pan gasket. The engine was full of rodent poop, acorns, leaves and cloth stolen from the interior. The oil pump pickup was clogged. Major cylinder wall scoring.

So my only choice in this pinch was to try and attempt the 4.6 block salvage. Since it ran low on oil I didn't like the coloration of the cam bearings. She got new cam bearings and all the rod/main bearings went into the 4.6 blocks. I did reuse the new(ish) piston rings with a few months of run time on them. That was a bit of a gamble but I did spend a good deal of time hoing the cylinders.


That was back last spring, no noticable oil consumption which I was worried about with reusing the piston rings.

No reports in drop off in power from the Frankenstein 4.0/4.6 hybrid I originally built.

I removed the dowel pins that align the timing chain cover before install. These pins being misaligned cause the oil pump failure so perhaps without them I will improve that alignment. That engine originally lasted maybe 80,000 miles, I hope to have a replacement before this one eats through.

Not a repair I'd do for a customer or someone who does extend travel in their rig as it's a gamble of if/when the oil pump fails again.

Even if the 4.6 didn't have a failed timing cover id have still used the 4.0 cover to keep the oil cooler. Does it need it? Probably not but we're in the South east and she drives the vehicle hard. I believe the 4.6 can be adapted to them but why go through the hassle when I have one that is a bolt on affair

I don't own a nanocom, as soon as used one comes up for a couple hundred I'll jump on it and play around with our spare 4.6 ECU and slabs (I've added a cable engagement for center diff lock) to see if I can add some power to it.

 

for what it's worth, i had two '04s. one with an oil cooler and one without. the one with the oil cooler also had a lift, 32" tires, and steel bumpers and always ran at lower temps than the stock '04. both had the inline thermostat mod and the same temp thermostats.