3.9i into Defender
Discussion
I have it in my head that I want to convert my 3.5 manual V8 Defender to auto, and potentially the easiest/best way to do so would be to get hold of a rotten D1 and lift all the bits I need out before weighing the rest in.
I'm fairly confident the engine will bolt straight in and I'm not too fazed about the gearbox potentially needing different mounts. I have a few propshafts lying about and worst case I can get them shortened. I've had the engine and box out of mine a couple of times, it's no massive deal.
I'm not planning to use the existing lump and mate an auto box to it. mostly because it's one of the low-compression jobs and whilst it's lovely and reliable, it doesn't have that much punch.
Main concern is over the ECU (and the fuel pump). I guess I may need a higher-pressure fuel pump than I currently have. And the ECU - how difficult would that be to wire in? I've got plenty of diagrams, just not sure how much additional wiring I'll need over the standard loom?
I know there are options like Megasquirt but I don't want to over-egg the task so if I can just hook up a regular ECU then all good.
Any other pitfalls I haven't clocked?
I'm fairly confident the engine will bolt straight in and I'm not too fazed about the gearbox potentially needing different mounts. I have a few propshafts lying about and worst case I can get them shortened. I've had the engine and box out of mine a couple of times, it's no massive deal.
I'm not planning to use the existing lump and mate an auto box to it. mostly because it's one of the low-compression jobs and whilst it's lovely and reliable, it doesn't have that much punch.
Main concern is over the ECU (and the fuel pump). I guess I may need a higher-pressure fuel pump than I currently have. And the ECU - how difficult would that be to wire in? I've got plenty of diagrams, just not sure how much additional wiring I'll need over the standard loom?
I know there are options like Megasquirt but I don't want to over-egg the task so if I can just hook up a regular ECU then all good.
Any other pitfalls I haven't clocked?
Thanks for that.
Another question from me. Looking around for scrap Discos, there seem to be more D2s than D1s for some reason. Difference is that the D2 has the 4.0 engine (and I think a different injection system to the 3.9?). I'm reasonably familiar with the 3.9 setup so that would be my preference but would the 4.0 also bolt straight in? And what other pitfalls might there be? Is that the version which suffers from liner slip?
Interestingly I called my insurance co to ask about any effect on premium for going 3.5 manual to 3.9 auto - the answer, a whole £16 p.a.
Another question from me. Looking around for scrap Discos, there seem to be more D2s than D1s for some reason. Difference is that the D2 has the 4.0 engine (and I think a different injection system to the 3.9?). I'm reasonably familiar with the 3.9 setup so that would be my preference but would the 4.0 also bolt straight in? And what other pitfalls might there be? Is that the version which suffers from liner slip?
Interestingly I called my insurance co to ask about any effect on premium for going 3.5 manual to 3.9 auto - the answer, a whole £16 p.a.
Just flagging this one back up. I now have the donor vehicle and when (if!) the weather improves, I'll set about the job.
Whilst I can probably flog my way through the wiring required to transplant the ECU and associated controls/sensors, it would be good to see what someone else has done re this. I've searched all manner of things trying to find out (for example, someone must have dropped this lump into a kit car in the past, as well as a Defender) but I can't find anything. If anyone can point me at any helpful resources, that would be great, thanks.
Whilst I can probably flog my way through the wiring required to transplant the ECU and associated controls/sensors, it would be good to see what someone else has done re this. I've searched all manner of things trying to find out (for example, someone must have dropped this lump into a kit car in the past, as well as a Defender) but I can't find anything. If anyone can point me at any helpful resources, that would be great, thanks.
100SRV said:
wheelbarrowman said:
I am about to convert my 84 110 to efi.
I would guess your donor vehicle is a hotwire type efi setup.
If you Google for 14cux efi or 14cux hotwire you'll find loads of resources. Some useful YouTube videos looking at sensors and wiring looms.
You may wish to check the status of the camshaft on your replacement engine before slotting it in.
What he said, wise words Mr Wheelbarrowman.I would guess your donor vehicle is a hotwire type efi setup.
If you Google for 14cux efi or 14cux hotwire you'll find loads of resources. Some useful YouTube videos looking at sensors and wiring looms.
You may wish to check the status of the camshaft on your replacement engine before slotting it in.
Don't forget that you will need an electronic Road speed signal so that idle speed is correctly controlled. Pm me if you need help with that.
Yes, it's the hotwire setup with the Lucas MAF sensor. Just had a quick google on 14cux and there is lots coming up, thank you. I had been googling "3.9i wiring" and variation on that.
Camshaft did cross my mind. The Defender currently has a low compression 3.5 on carbs and that would also probably be in need of a cam if I was keeping it. General rule is c. 100k miles iirc?
100, I'll have to drop you a line then as the road speed signal is a new one on me, not sure what that's about.
Cheers for that. I have Rovergauge from when I had the RRC.
My plan, I think, is to try and isolate the entire engine, ECU etc from the car and get it running with the key components screwed to a board, so that I know it runs in isolation before I get rid of the hulk it came from and so that I know what I need when I drop it into the Defender.
There's lots of useful info around (thanks to the posters above for that) although I still haven't quite got my head around how much of the Disco loom I need, and conversely what I can discard.
My plan, I think, is to try and isolate the entire engine, ECU etc from the car and get it running with the key components screwed to a board, so that I know it runs in isolation before I get rid of the hulk it came from and so that I know what I need when I drop it into the Defender.
There's lots of useful info around (thanks to the posters above for that) although I still haven't quite got my head around how much of the Disco loom I need, and conversely what I can discard.
wheelbarrowman said:
Some useful YouTube videos looking at sensors and wiring looms.
I went off and hunted yesterday (been a busy few months on other stuff!) and found this:https://www.youtube.com/watch?reload=9&v=NkH5l...
which is the answer to all my prayers (so far!). Tells me exactly what I need to retrieve from the Disco and what to do with it when I've got it.
I kept reading things like "you only need 4 wires for a 14CUX" but nobody ever said what those were or where they went, but here we are.
I think I'll drag all that out to underneath the bonnet on the Disco and then check I can still start it before I finally remove it all.
I'll be back with more questions I'm sure, such as fuel pump/swirl pot, and whether or to to use the lambdas (and how)!
Latest update on this:
I dragged all the relevant loom sections, relays and ECU into the engine bay so that they were completely disconnected from the car, and then set about running temporary wires to convince myself that I could get the engine running independent of the Disco. Took me a couple of goes but this afternoon it ran
One small step for man, but I'm rather pleased with myself. Now the I've achieved that, the rest is simple. Ish. I've no qualms about the nuts & bolts bit, so it will just be things like the speed sensor mentioned above, the safety switch on the gearbox, etc.
I managed to completely knacker my back a week ago, so today I was OK standing in front of the car and crimping/connecting wires, but I can't do much else just yet. Once I'm fixed I'll be looking at dragging the lump out and getting rid of the hulk, before the fun really starts.
I dragged all the relevant loom sections, relays and ECU into the engine bay so that they were completely disconnected from the car, and then set about running temporary wires to convince myself that I could get the engine running independent of the Disco. Took me a couple of goes but this afternoon it ran
One small step for man, but I'm rather pleased with myself. Now the I've achieved that, the rest is simple. Ish. I've no qualms about the nuts & bolts bit, so it will just be things like the speed sensor mentioned above, the safety switch on the gearbox, etc.I managed to completely knacker my back a week ago, so today I was OK standing in front of the car and crimping/connecting wires, but I can't do much else just yet. Once I'm fixed I'll be looking at dragging the lump out and getting rid of the hulk, before the fun really starts.
robertf03 said:
that 4 wires is misleading. It would look like a plate of spaghetti if thats all that you had to hook up
Did this one a few months ago
That's a very neat looking install, I like what you've done with the air filter.Did this one a few months ago
All I had to do to get the 3.9 running independent of the Disco was:
- 12v permanent power to the ECU
- 12v switched (spoofing ignition on) to the coil
- 12v pulse cable from coil to ECU
- 12v to starter solenoid
I don't know what was going on with my phone, it's a terrible photo, but.......progress has been made 
(Yes, I cheated and zipped out the middle of the slam panel on the Disco. In my defence, this was done 100% single-handed, on the drive, I'm scrapping the Disco anyway and it meant less lift height needed. It's all removable on the Defender.
(Yes, I cheated and zipped out the middle of the slam panel on the Disco. In my defence, this was done 100% single-handed, on the drive, I'm scrapping the Disco anyway and it meant less lift height needed. It's all removable on the Defender.
Thread resurrection time!
Well, whilst things stalled a little over the winter (time constraints plus I'm too old to be rolling around on a frosty drive), the latest is that....drum roll please....I have a running V8i in the Defender
I went for the Defender pump/swirl pot/HP pump option as per 100SRV above. Works fine so far, I won't know whether it shifts enough fuel until I get to drive it properly. It's ticking over OK at present but I do still need to connect the cabling from the rear of the gearbox which I think will give me the speed sensor (although not drive the speedo, thats another thing to tackle, looking at the TD5 electronic speedo option currently).
It's been interesting coming up with engineering solutions to various things, and still got a long way to go, and I have to sort all the wiring properly, which brings me to.....ECU location.
Those of you who have this conversion installed, where's your engine ECU located? My engine and loom came out of the Disco, and I gather the ECU loom is shorter than that in the RRC, which means that bolting it to the rear bulkhead isn't an option (unless I buy and swap the loom which I'm less than keen to do). Current thoughts are in the battery box, under the centre cubby, or fabricating something when I make up the new transmission tunnel to include it in that. I remember reading somewhere that someone had put it under the steering column but I think it's a bit big for that. Also need to be mindful of not drowning it - not that I drive through waist-deep water, but it's a consideration.
I'd also be interested to know what people have done about an air filter? Current thinking is to fab a bracket to hold the MAF onto the inner wing and use a cone filter - not ideal but there's no room for a big airbox.
Hoping to get a few more bits done this weekend and to bolt the props on so that I can just run it up the road.
Well, whilst things stalled a little over the winter (time constraints plus I'm too old to be rolling around on a frosty drive), the latest is that....drum roll please....I have a running V8i in the Defender
I went for the Defender pump/swirl pot/HP pump option as per 100SRV above. Works fine so far, I won't know whether it shifts enough fuel until I get to drive it properly. It's ticking over OK at present but I do still need to connect the cabling from the rear of the gearbox which I think will give me the speed sensor (although not drive the speedo, thats another thing to tackle, looking at the TD5 electronic speedo option currently).
It's been interesting coming up with engineering solutions to various things, and still got a long way to go, and I have to sort all the wiring properly, which brings me to.....ECU location.
Those of you who have this conversion installed, where's your engine ECU located? My engine and loom came out of the Disco, and I gather the ECU loom is shorter than that in the RRC, which means that bolting it to the rear bulkhead isn't an option (unless I buy and swap the loom which I'm less than keen to do). Current thoughts are in the battery box, under the centre cubby, or fabricating something when I make up the new transmission tunnel to include it in that. I remember reading somewhere that someone had put it under the steering column but I think it's a bit big for that. Also need to be mindful of not drowning it - not that I drive through waist-deep water, but it's a consideration.
I'd also be interested to know what people have done about an air filter? Current thinking is to fab a bracket to hold the MAF onto the inner wing and use a cone filter - not ideal but there's no room for a big airbox.
Hoping to get a few more bits done this weekend and to bolt the props on so that I can just run it up the road.
wheelbarrowman said:
I have a tdci seatbox, the ECU just sits inside it.
I have 110 so fuel tank over back axle. I used to have a leaky long range auxiliary tank, but removed it when replacing seatbox.
Ah I see, thanks. I think the battery box (under the passenger's seat) is going to be favourite for me, I'll either bolt it to the side or make a shelf for it.I have 110 so fuel tank over back axle. I used to have a leaky long range auxiliary tank, but removed it when replacing seatbox.
Just filled it up with coolant and had it running longer, burning all the oily hand marks off the exhaust manifolds
Really want to get the props on and get it moving but I'm a bit under the weather at the moment so anything requiring significant physical work is a no no. It sounds glorious on the open Disco 2 > 1 headers with only the cats though. Deep and burbling but not outrageously noisy. I think a nice 2.5" exhaust with a small silencer will be the way to go. This is turning into the longest project ever. However.....
.....drum roll please: today I drove it along the road (and back). That's the first time it's moved under it's own steam with the 3.9 in it. Literally just along the road and back as there are still far too many parts missing from it, but I just needed to prove it would move. So, another burst of energy towards getting to finished.
Still entirely one person's work, (well, plus this and a few other forums), so there's a certain sense of achievement involved.
.....drum roll please: today I drove it along the road (and back
). That's the first time it's moved under it's own steam with the 3.9 in it. Literally just along the road and back as there are still far too many parts missing from it, but I just needed to prove it would move. So, another burst of energy towards getting to finished.Still entirely one person's work, (well, plus this and a few other forums), so there's a certain sense of achievement involved.
OK, so I'm back with another question!
I need to wire in a start inhibit for Park/Neutral. The gearbox has a switch for this (I believe it earths the connection in P/N) but on the donor car that goes back through the ECU and presumably thus into a relay somewhere which I don't have (nor the wiring for).
So my plan is to wire in a separate relay, which will operate via the gearbox switch earth, and the switch side will sit in the starter motor solenoid circuit. Ignition on, car in P/N and the relay coil circuit is made and the starter will operate; once in any other position the relay will drop out, so the relay coil won't normally be energised.
Seems simple to me but am I missing anything?
Also, I have a 30A relay but the starter solenoid cable (I'm using the existing Defender wiring for that) is quite a heavy gauge. Surely the solenoid (not the starter) won't draw a huge amount of current?
I need to wire in a start inhibit for Park/Neutral. The gearbox has a switch for this (I believe it earths the connection in P/N) but on the donor car that goes back through the ECU and presumably thus into a relay somewhere which I don't have (nor the wiring for).
So my plan is to wire in a separate relay, which will operate via the gearbox switch earth, and the switch side will sit in the starter motor solenoid circuit. Ignition on, car in P/N and the relay coil circuit is made and the starter will operate; once in any other position the relay will drop out, so the relay coil won't normally be energised.
Seems simple to me but am I missing anything?
Also, I have a 30A relay but the starter solenoid cable (I'm using the existing Defender wiring for that) is quite a heavy gauge. Surely the solenoid (not the starter) won't draw a huge amount of current?
100SRV said:
CAPP0 said:
OK, so I'm back with another question!
I need to wire in a start inhibit for Park/Neutral. The gearbox has a switch for this (I believe it earths the connection in P/N) but on the donor car that goes back through the ECU and presumably thus into a relay somewhere which I don't have (nor the wiring for).
So my plan is to wire in a separate relay, which will operate via the gearbox switch earth, and the switch side will sit in the starter motor solenoid circuit. Ignition on, car in P/N and the relay coil circuit is made and the starter will operate; once in any other position the relay will drop out, so the relay coil won't normally be energised.
Seems simple to me but am I missing anything?
Also, I have a 30A relay but the starter solenoid cable (I'm using the existing Defender wiring for that) is quite a heavy gauge. Surely the solenoid (not the starter) won't draw a huge amount of current?
No, I don't think so, I use a standard mini relay to control the feed to my starter solenoid.I need to wire in a start inhibit for Park/Neutral. The gearbox has a switch for this (I believe it earths the connection in P/N) but on the donor car that goes back through the ECU and presumably thus into a relay somewhere which I don't have (nor the wiring for).
So my plan is to wire in a separate relay, which will operate via the gearbox switch earth, and the switch side will sit in the starter motor solenoid circuit. Ignition on, car in P/N and the relay coil circuit is made and the starter will operate; once in any other position the relay will drop out, so the relay coil won't normally be energised.
Seems simple to me but am I missing anything?
Also, I have a 30A relay but the starter solenoid cable (I'm using the existing Defender wiring for that) is quite a heavy gauge. Surely the solenoid (not the starter) won't draw a huge amount of current?
Do you have ballasted or non-ballasted ignition coil?
If you have an automatic gearbox the 14CUX ecu needs to know when neutral is selected too.
What does the neutral feed to the ECU do? I guess I can parallel that connection with the solenoid relay.
Many thanks for your input on this, it's been invaluable and very much appreciated! I received all the Jetex parts and mocked up the exhaust last weekend, very similar to yours although I have a slight issue with chassis clearance and exit point, mine not being the same as yours there, but it will be workable although I will probably have to alter the rear 3/4 behind the wheel.
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