GEMS or Bosch

[boxerhips]

Has anybody tries to replace a 3.9 with a 4.6 (And use the GEMS or Bosch Fuel Injection)? Can this be done without using the wheel sensors? Tim

[jaherring]

If you want to use the 3.9's sensors and ECU it should be fairly easy. If you want to convert to GEMS... ugh, lots of rewiring work, new ECU, new inteface to the dashboard... sounds like a big mess to me.

[Roadsiderob]

Replacing the 3.9 with the 4.6 is no problem. What perceived benefit will you get by spending the time and money to switch to GEMS or Bosch fuel management?
Rob

[boxerhips]

I can get a 4.6,trans,xfer w/ECU and all wiring for cheap. When crossing water the "wet" distributor has been a problem and I know the truck runs rich. I have a wide-band O2 and it reads 12 to 1 all the time. I've tried different plugs, wires ect. and I've tried a SAFC(goes between the mass air and the computer). The mass air on the 3.9's DON'T correct that much. Any thoughts? Tim

[Mike Hippert]

Hmm, I thought I remember there is a screw of some type on the MAF to adjust it if you are rich or lean? I like the idea of the coil packs too, but the reality of it is you are adding 3 times as much junk that cannot get wet in order to run those coil packs. That and the 14CUX is much easier to trouble shoot when out in the field!

[Hans]

Well, if the mixture is constantly reading 12:1, that may actually be correct. IIRC, the Hot-Wire system runs very rich when configured for use with catalytic convertors. There are 4 or 5 different tune settings stored inside the computer, and which one is determined by a resistor. I've seen it mentioned a few times in UK forums that having the 'Cat' resistor, but no catalytic convertors, will result in extremely high emissions.

Some places make reference to a 'Green' resistor and a 'white' resistor, which are the two options use in UK vehicles.

Somewhere I've seen the actual resistance measurements for the different options as well as where they are used. I've been wondering for a long time the actual difference in the fuel mapping between them, but nobody has ever properly tested them out. I'll try to find the numbers out there

-Hans

[Roadsiderob]

If you want to go that deep, get a diesel and a good snorkle. The Bosch system will be way too much trouble as its ECU communicates with the ABS, transmission, Instrument pack, and others. It is not really a viable swap unless you have extremely deep pockets. The Gems system would be easier but you still have the road speed sensors to contend with as well as the alarm control unit. If you really want Gems...trade your truck for a 1997. Gems is not really better than 14CUX...it just has different problems and is less field fixable.

[Hans]

Found it!

The aussie (no cats) is 180 ohm.
The UK (no cats) is 470 ohm
The Saudi (no cats ) is 910 ohm.
The Cats one is 1.2k ohms.

There is additional cat tune in there, but I can't confirm the resistance for it. RPi says there is a 3900ohm cat resistor as well, which is possibly the missing one. No resistor will enter a 'limp home' mode, which apparently runs like crap and is RPM limited.

1/2 watt or larger resistors can be used, but it's recommended to use the good 2% ones.
It is located between pins 5 and 27 on the ECU, wire colors are white/black and white/grey. The resistor itself will be in a small blue plastic housing.

Not sure what else the different tune settings alter besides the fuel map. I'd be interested to see how much of a difference it is, and if it's worth it to change resistors?

-Hans

[boxerhips]

Thanks for the replies. I found out the truck is a 1998 4.6HSE. I think that is a GEMS. I don't know what xfer case it has. I would like to keep it together, if possible. I can get everything I need (computer ect), for cheap. It has an auto trans, but I don't know if I would use or sell. Is there a demand for a used auto from a RR? Tim

[Hans]

Oh, and regarding the distributor issue. Have you considered trying either the Mallory Unilite or possibly an MSD system instead? Both can be easily be made to fit the Rover 3.9 engine. Either that, or maybe a waterproof boot over the whole thing?

-Hans

[Roadsiderob]

The trans and t-box would be no good to you. The t-box is a Borg warner box with the outputs on the left side...the D90 is opposite. The Auto trans is computer controlled. You'd have to either incorporate the computer or swap it for an older, non electronic one...probably swap it for a non electronic one as I think the same ecu also controlls the t-box that you can't use. If you're really gonna do this, maybe get an ECU out of a 5speed Gems Disco and keep the R380.

[boxerhips]

Hans thanks. When my truck is running again I will try different resistors. I will post findings. Just for some info on AFR. In my Mustang ( I know its not Land Rover, but AFR is AFR), when its @ 12 to 1 the gas mileage and the performance is terrrible, @14.7 to 1 night and day better. The Ford EEC does a great job in keeping the AFR around 14.7 to 1. You can change alot before you run into problems(like a 15lb procharger and double the fuel pressure), in fact I would live to try a ford EEC in my D-90, if I just used a Tweecer to control the EEC I know it would work great. How much time it would take, I don't know. When I get it running I'll re-record AFR(wideband), RPM'S, and mass air voltage. It only records 2 minutes at a time and has since been cleared. Thanks Tim

Follow-up Post:

Hans I have a Mallory unilite installed(sort of). My vacuum advance when bad and I had a SBC unilte laying around. I just replaced the LR parts with the Mallory parts. Made no differnce at all in the water problem. But the vacuum advance is MUCH better. First it fits on the factory distributor and the part is $25-$30, much cheaper than a new distributor. It also adds about 10° witch helps parts throttle response. Tim

[Hans]

Wait, did you replace the entire guts of the distributor with the optical module from the unilite? or just the vacuum advance? (interested to hear of this possible option!).

I know that you can also replace the LR ignition module with a 4-pin HEI from GM since they use the same type of sensor. I've also seen waterproof boots that cover the whole distributor head, that may help the issue as well. The real question before I start really suggesting a fix though is what problems were you having with water and the distributor? Was water getting into the sensors? or splashing on the module?

Mike Hippert and I were also toying around with the Megasquirt EFI system. I have it up and running in my CJ-7 at the moment, but Mike had issues adapting it and a ford ignition ECU to his 4.6. It would be a no-brainer to install it in a 3.9, you could even use all the pre-existing sensors other than the factory 02 sensors. Since you said you already have a wide-band O2 you're a few steps ahead of the game as well, since it can support the widebands for the fuel control.

Later versions of the Megasquirt can use a few different types of ignition systems to give full spark control as well, if you want to go to that length. I eventually plan on swapping the D-90 over to Megasquirt as well, and also using the later THOR intake manifold if possible. Supposedly it gives better torque and extends the power curve a lot lower in the RPM band. But I have a few other things to take care of first.
-Hans

[boxerhips]

Hans I replaced evrything except the shaft(chevy was to long) and the cap (locks different). Mike is using what Ford EEC in his 4.6? Mass air or speed density? Is he using Land Rover distributor? Tim

[Hans]

Honestly, I don't know which version he was using. Sorry I can't help more on that. He had a long and rapidly changing project when he was re-doing his engine.

-Hans

[Mike Hippert]

I was trying to use the megasquirt with a Ford EDIS module, but you need an auto flywheel to make it work. The manual flywheel does not have the pickups on it for the crank sensor that triggers the ignition of the EDIS.

This would have been great because I would kill 2 birds with one stone, I would be running the megasquirt as an ECU (it's simple and you can hook it to your laptop and get real time readings of every sensor! then adjust your fuel injector rates and all kinds of other good stuff!) and 2 the EDIS mudal controls the spark coming out of the coil packs. YOu also control the EDIS fro the megasquirt! That means you basicly have control over everything on the engine!

I really wish this would have worked out but I just didn't want to pull the engine again so that I could somehow mount pickups for the crank sensor to the flywheel. The sensors are mounted on the engine side of the flywheel, they are on a band that is rivited to the flywheel and I really didn't want to spend allot of $$ and time getting it mounted (I still didn't have all the bugs worked out) so I opted out of it and went back to the 14CUX.

The EDIS is a popular coil pack controler in the antique car world because it is so simple to use. Check it out.

http://www.dainst.com/info/edis/edis.html

In theroy you could use it with the 14CUX, but i am not you would need something to advance and retard timming unless the crank pickups were offset when they were mounted so the timming was set properly.

Anyway, food for thought.

[Roadsiderob]

Mike,
If you ever try to go this route again...look at a flywheel from a 1996 Disco with an R380...has the sensor ring already there.

[Mike Hippert]

Ahhh good to know. I'll have to keep my eye out for one!

[JimC]

Yeah, this is interesting. I'm thinking about running a disco v8 with manual trans to update the 110 project until I get around to dieseling the thing. I'm hoping to find something cheap. Some of it will depend on how well the old carb v8 runs but I've been dying to experiment with the megasquirt!

[Roadsiderob]

Jim,
I've got a customer who is going to be doing a diesel conversion very soon and will have all the EFI bits left over from the 14CUX system. There is also a replacement manifold available from Edelbrock to fit a Holly carb. I converted a couple of grey market Range Rovers this way. Honestly, though, I think the original side draft carbs run fine when set up properly. There is a guy back east...Joe Curto...that specializes in rebuilding those carbs. The web site is www.joecurto.com . I bought a book and the mixture setting tool from him to work on a customers 110.

[JimC]

Thanks Rob - cheap is going to be the operating principle. If carbs run well, then carbs it is. Part of replacing everyting would be the desire to get the r380 and lt230.

[Roadsiderob]

Jim,
As old as it is, it may have an LT95 or LT85 transmission. The carbs are ok but you have to keep them filled with the proper weight oil (apparently, in the UK, everything must be made to leak oil, even carburettors) or they don't work correctly(SAE20wt). The oil is used for damping and if it is incorrect viscosity or empty it will have an adverse affect on how fast the piston rises and can change the running characteristics. Make sure the guys check these before they leave and also during the trip. They are pretty simple overall, though. Most mechanics don't want anything to do with them because they don't understand them....there's nowhere to plug in a diagnostic tool. What you need to do is find yourself an old tyme mechanic...someone who worked on old Jaguars when they were new...or vintage races old british cars or something. See if you can pay him for some of his time and have him teach you how to tune them. Do this as soon as possible because these older guys are retiring now and the knowledge is going with them. The gentleman that taught me used to race Alpha Romeos...he had lots of fun stories about that...and he retired a couple of years ago.
I can't wait to see it.
Rob

[jaherring]

I'm trying to picture the crank triggers on the flywheel - are these magnetic tabs attached to the flywheel? A friend of mine does custom aftermarket EFI work and just drills into the flywheel a small hole (1/8"?) and installs a rare earth magnet (cylinder in shape) for the pickups on older aluminum Buick V8's. Works great. But, I guess, if you can find a factory setup it would be alot easier for you.

I'd like to do the megasquirt as well and interface it with my onboard carPC - but I guess it doesn't support the 'check engine' light and might get caught by the emissions 'referee'. What I really want now is a knock sensor and a way to retard my timing based on it, as on hot days with cheap gas I get nasty pinging with the 3.9L EFI setup (I've already retared the ignition to 0deg TDC to try to eliminate this - if I use premium, this works but....)

Can someone tell me - is there a difference between the Disco ECU and the D90 ECU of the same MY? The engines seem to show different HP/torque specs (from one source anyway). Is there any benefit to running the Disco ECU in the D90?

The MAF resistor change is intriguing. Will the cats get too hot if the mixture is leaner than 12:1? What's the extra fuel used for on a cat-truck?

I was trying to use the megasquirt with a Ford EDIS module, but you need an auto flywheel to make it work. The manual flywheel does not have the pickups on it for the crank sensor that triggers the ignition of the EDIS.

This would have been great because I would kill 2 birds with one stone, I would be running the megasquirt as an ECU (it's simple and you can hook it to your laptop and get real time readings of every sensor! then adjust your fuel injector rates and all kinds of other good stuff!) and 2 the EDIS mudal controls the spark coming out of the coil packs. YOu also control the EDIS fro the megasquirt! That means you basicly have control over everything on the engine!

I really wish this would have worked out but I just didn't want to pull the engine again so that I could somehow mount pickups for the crank sensor to the flywheel. The sensors are mounted on the engine side of the flywheel, they are on a band that is rivited to the flywheel and I really didn't want to spend allot of $$ and time getting it mounted (I still didn't have all the bugs worked out) so I opted out of it and went back to the 14CUX.

The EDIS is a popular coil pack controler in the antique car world because it is so simple to use. Check it out.

http://www.dainst.com/info/edis/edis.html

In theroy you could use it with the 14CUX, but i am not you would need something to advance and retard timming unless the crank pickups were offset when they were mounted so the timming was set properly.

Anyway, food for thought.

[Roadsiderob]

Jason,
The factory setup on a disco1 uses a series of drilled holes that are interconnected to form the reluctor ring teeth that the sensor tip reads. I believe the ECUs are pretty much the same...the disco chip not having a speed limiter, though.

[Mike Hippert]

I still have the old flywheel I'll take a pic when i get a chance, IIRC it is a ring on the ineer side of the flywheel with tabes about 1/4" tall bent 90* as a magnetic pickup.

[JimC]

Jim,
The gentleman that taught me used to race Alpha Romeos...he had lots of fun stories about that...and he retired a couple of years ago.
I can't wait to see it.
Rob

All that is a good point Rob - this truck will really be more akin to series than a defender. I'll ultimately give it the ol' ground up like my current truck, but the more I think about it, the more I realize its going to be a lot of fun to run in its current configuration.

Incidentally, I met an old Alfa mechanic that taught me how to tune Webers (not that I'm very good at it!) when I bought my GTV. I love those old guys, this guy would tune the car almost entirely by ear and it never ran better. Truly a dying art.

[boxerhips]

Mike couldn't you just use a MSD pickup( the one that goes on the front dampner)? What aftermarket distributors will fit a Land Rover 3.9? Tim

[Mike Hippert]

Mike couldn't you just use a MSD pickup( the one that goes on the front dampner)? What aftermarket distributors will fit a Land Rover 3.9? Tim

Someone mentioned that before, but as i recall they are not shelled against water, dirt and mud very well.

[jimmy salmon]

I had a RR with the SU carbs and the piston was always sticking.In the UK we used a 3 in 1 oil which is a very light oil.If the truck is run often they are fine they only seem to stick if left for a while.I mentioned this to Mike the other week.

[Davis]

Tim, Mallory (which I am running) and MSD both make distributors for the 3.9--there may be others, but I have not heard reports. None of the distributors are sealed up really well--one simple method for keeping water out that I have seen is taking a small air bubbler pump like used in fish tanks, throw a switch on it for water crossings, and have it pump air into the distributor via a small hose creating a positive pressure--water won't be able to get in.

[boxerhips]

Davis I have never heard of "the old airpump trick", it sounds like it would work great. The distributors that fit (Mallory or Msd) do they work with their external control boxes or do they work with any coil? Tim

[Hans]

The Mallory needs the drive gear swapped, but will otherwise wire right into the system. You can either use the external box or not, you're choice.

The MSD requires the box just to function. Not sure if it needs a tach adapter ornot.

-Hans

[boxerhips]

Hans Does the Mallory or the MSD feed back to the ECU? I've read theat you can use a Buick HEI 350 distributor and it only requires 1 wire (12+), but doesn't the distributor "talk" to the ECU for fuel injector timing? Tim

[Hans]

Yep, but it's just a simple tach feed. It's not a 2-way connection, just a single wire from the Distributor to the ECU.

Under the HEI cap, the connector is right next to the 12volt power line.
With an MSD setup, it's the tach connector on the ignition box
Not sure where the Mallory crowd is hooking into the system. It's most likely from the negative terminal off the coil.

One problem I have heard with the HEI setups is that they don't clear the entire intake manifold and some grinding is needed.

You know, all that time under the hood, I still haven't identified which wire that the Lucas distributor uses for the EFI feed. I don't know if it goes to the distributor module or to the coil.

-Hans

[jaherring]

Electromotive coilpacks are pretty resilient & can get wet. The control box for them can be located in the passenger compartment (I'd put it next to the battery) and is weather-resistant (the manufacturer suggests not putting it in the engine bay, but goes on to say that the circuit board is resin-sealed and waterproof...)