My 4.6 V8 Rebuild Thread

[Davo]

I have fitted Megajolt to a 4 cylinder petrol engine (not unlike a Series) and if it helps to assuage anyone, it is a very straight-forward and relatively simple exercise to fit; especially if the engine is out of the car.

The improvement to the performance of the car is astonishing and fortunately for Rover owners, the hardest bit of programming the advance table, has already been done by countless people and so it is easy to obtain a copy from them.

I have also purchased a Megasquirt for my Disco but not yet fitted it but it is essentially the same skills;
1. The ability to read instructions and manuals and comprehend how the system works.
2. Basic metalwork skills to fabricate brackets if desired and to solder electrical connections.
3. A logical mind, which can test and isolate parts of a circuit to confirm functionality.
4. An ability to understand electricity - something I am teaching myself with a u-beaut book.

If you can do these things, no one need worry about the system breaking down and being unrepairable. There is very little that can go wrong anyway! The most expensive component is the MJ, or MS ECU, the rest of the components can be salvaged off car wrecks. One chap in New Zealand, has installed MS on his RR Classic using Hyundai and some other Jap electronic parts.

MJ is fantastic and eliminates the advance timing losses associated with a distributor forever. MS is supposedly even better and eliminates the inefficiencies of a carburettor forever with heaps of other benefits,

Cheers Charlie

I'll bet it's that good, but you still have to think about exactly what you'd do if you have trouble. It's not always a matter of just setting up camp and working it out - you may need to be quicker than that. So if you really know what you're doing and have the spares to hand, then I can see it would be great for lunatics I mean enthusiasts like us. I'd be inclined to go for something where you could just plug in new parts to troubleshoot, which sounds quite nice, actually!

One of the worse things these days with the Rover V8 is the quality of ignition parts, which seems to vary from "hopefully as good as Genuine sort of used to be" to "falls apart in five minutes", which actually happened to me with a rotor. So even if, like me, you're trying to apply the KISS principle, just that can make a mess of things. I was considering that GM HEI dissy you can get from US eBay, but other than that, I think it would be Megajolt.

[chazza]

I'll bet it's that good, but you still have to think about exactly what you'd do if you have trouble. It's not always a matter of just setting up camp and working it out - you may need to be quicker than that. So if you really know what you're doing and have the spares to hand, then I can see it would be great for lunatics I mean enthusiasts like us. I'd be inclined to go for something where you could just plug in new parts to troubleshoot, which sounds quite nice, actually!

Fair call and it was how I felt when I first read about MS; however; the good news is this;
1. If a Ford EDIS is used, they are very robust; can withstand engine bay heat provided they are mounted on a heat-sink; and they are water-proof, unlike a distributor. EDIS also defaults to 10 degrees advance in limp-home mode if the ECU karks it - I have driven mine in limp-home mode and it still gets along quite well.
2. Ford coil-packs, or similar, are also reliable and water proof, so much so that the nuts in the UK drive with their engines under water!
3. The Ford VR sensors are very cheap and easy to replace on the road if necessary and about the size of a spark plug.
4. The ECU - like most ECU's - needs to be kept dry and coolish inside the car. Apparently they rarely fail unless someone fries one by connecting the power to the wrong terminal. If they do fail see point 1.
5. You can plug in new parts when trouble-shooting, the only expensive part is the ECU, but like most things they can be tested for function.

The system is no more unreliable, or difficult to fix, than a distributor/injection system,

Cheers Charlie

[slug_burner]

Gary,

In your research have you established what it is that makes the Thor more difficult to manage with a Megasquirt? I have not had to worry about V8s and the only petrol motors I have at the moment are in Siamese 1.6 and 2.0 ltr inlet over outlet engines.


What sort of air metering system does it use? Is this where the difference is?

I have been learning about this Thor engine and at this stage does not sound to be significantly different to other fuel injected engines. I have been reading this site http://www.landroverclub.net/Club/HTML/V-8_40new.htm and have found that the flywheel has bores in it to serve the same purpose as the toothed wheel and has the necessary sensor, also has a cam sensor. Even has oxygen sensor to provide a closed loop control system. The more I read the less I understand why the Thor engine is considered such a challenge. I think it is more a case of it having a reasonable motronics Bosch system therefore little reason to change. Maybe the professional mechanics can clue us up as to any oddities of the Thor engine and it's management system.

[Davo]

Fair call and it was how I felt when I first read about MS; however; the good news is this;
1. If a Ford EDIS is used, they are very robust; can withstand engine bay heat provided they are mounted on a heat-sink; and they are water-proof, unlike a distributor. EDIS also defaults to 10 degrees advance in limp-home mode if the ECU karks it - I have driven mine in limp-home mode and it still gets along quite well.
2. Ford coil-packs, or similar, are also reliable and water proof, so much so that the nuts in the UK drive with their engines under water!
3. The Ford VR sensors are very cheap and easy to replace on the road if necessary and about the size of a spark plug.
4. The ECU - like most ECU's - needs to be kept dry and coolish inside the car. Apparently they rarely fail unless someone fries one by connecting the power to the wrong terminal. If they do fail see point 1.
5. You can plug in new parts when trouble-shooting, the only expensive part is the ECU, but like most things they can be tested for function.

The system is no more unreliable, or difficult to fix, than a distributor/injection system,

Cheers Charlie

That's pretty much what I thought and it sounds like the troubleshooting isn't too different to the Land Rover electronic ignition in how you can just replace bits. Except without the annoying moving parts of a distributor. It sounds great, now for the money money money money ergh bit of the whole thing. Thanks a lot for explaining it.

[101RRS]

In your research have you established what it is that makes the Thor more difficult to manage with a Megasquirt?

I have been learning about this Thor engine and at this stage does not sound to be significantly different to other fuel injected engines.

Might be on on shakey ground here so if anyone definitely knows please pipe up.

The Thor runs a common rail system that maintains a contant fuel pressure. Injectors are fired sequentially like in a CRD and controlled by the ECU. As far as I am aware (and this I am not sure of) earlier GEMS and 4CUX systems batch fire injectors in batches or banks but only the injector in the compressed cylinder has fuel.

Looking at the specs of the different MS versions it is only MS3 that can fire 8 injectors individually where the other versions cannot - see a comparisons here Understanding the MegaSquirt lineup: Pre-Assembled Wire-In EMS Systems

However the Brits do not like MS3 (they say too expensive and complex yet their systems are more expensive) and are trying to modify MS1 to work. What I suspect what they are trying to do is use the Thor Plenum etc but use a Gems fuel supply system and bank injection so you get the low down torque of the Thor with the more simple injection system of the Gems system - but I don't know. Maybe this is why the proposed Brit Thor - full kit - not just ECU is over 1000 pounds.

Garry

[101RRS]

I'll bet it's that good, but you still have to think about exactly what you'd do if you have trouble.

Certainly reliability is a consideration but the issue you raise is relevant to any modern offroad vehicle. If I had an ECU fail on my RRS when offroad it would be dead with no chance of being fixed on the spot.

Garry

[slug_burner]

I too read that the common rail fuel system had no return line to the tank on the Thor.

My reading reveals that the early Motronics did batch fire the injectors in two banks. I did not pickup anything about fuel in only one injector, that is not possible on a common rail system. What I thought I read was that the injectors on a four cylinder injected half the fuel required each time the bank fired, that was for a four cylinder. Later Motronics systems had sequential systems so only fired the required injector.

One thing that I recall that might be old hat now was that the spark characteristics were used to measure the load the engine was under in the Thor.

I'll look into how the injectors are controlled with the earlier MS. Injecting on two banks of a V8 would require the injectors to deliver 1/4 of the fuel each time they fired. There must be other ways, the only thing that is coming to me at the moment is that the injectors would be fired using some logic external to the MS.

[101RRS]

My reading reveals that the early Motronics did batch fire the injectors in two banks. I did not pickup anything about fuel in only one injector, that is not possible on a common rail system.

I was not talking about Motronics which is the Thor system but Gems and 4CUX. I agree not possible on a common rail system.

In a batch/bank system where more than one injector fires how do the extra injectors either not inject fuel and if they inject less than required how does the engine make enough power.

As I have Thor stuff I have not looks at how Gems works.

Garry

[Hoges]

I too read that the common rail fuel system had no return line to the tank on the Thor.

My reading reveals that the early Motronics did batch fire the injectors in two banks. I did not pickup anything about fuel in only one injector, that is not possible on a common rail system. What I thought I read was that the injectors on a four cylinder injected half the fuel required each time the bank fired, that was for a four cylinder. Later Motronics systems had sequential systems so only fired the required injector.

One thing that I recall that might be old hat now was that the spark characteristics were used to measure the load the engine was under in the Thor.

I'll look into how the injectors are controlled with the earlier MS. Injecting on two banks of a V8 would require the injectors to deliver 1/4 of the fuel each time they fired. There must be other ways, the only thing that is coming to me at the moment is that the injectors would be fired using some logic external to the MS.

I read that as well about the plugs, and apparently the OEM spark plugs were specified particularly for that reason...

[slug_burner]

I think they rely on the fuel staying atomised in the port, for a four two shots from the injector for every time the inlet valve opens. I think that would be a less likely method for an 8.