Rover V8 MegaSquirt P38 4.6 – extraEfi

The original plan was to utilise a John Earle Engineering tweaked ECU, but along came a bargain cheap MS1 Rover V8 Megasquirt made by extraEfi previously fitted to a 4.6Litre Stag. A separate purchase gave me various hoses, brackets and pipes necessary.

This particular MS1 Megasquirt had built in IGBT coil pack drivers meaning I didn’t need to use that Ford Edis-8 ignition module I had stuffed under the bench. It also had a wiring loom.

A few minutes on the web found circuit diagrams, connector pinouts, photos, forum installation diaries and more.

Confidence was high.

Once in the garage, confidence fell a little, as it was obvious that numerous connectors were missing from the loom. The hoses, tubes and brackets were obviously for a early 3.5 Land Rover, at best they’d need cutting up if not scraping.

After a few evenings of research it became apparent that although some have enjoyed Rover V8 Megasquirt success, many had become frustrated with what seemed like an endless series of issues. Several had employed specialist tuners and had still given up.

I’d recommend reading this post: Megasquirting a V8 – how to basics – long but worth it

Rover V8 Megasquirt Problems

• Bad Grounding
• Incompatible sensors
• Poor idle
• Unable to turn off
• Constant resets
• Wrong wire sizes
• Wrong sensor pinouts
• Old tuning software
• Wrong firmware versions
• Choice of Lambda sensors
• Not to mention tuning

Rover V8 Megasquirt Observations

Once offered up to the engine it was instantly obvious that the wiring loom was the wrong length and designed for a different vehicle, I therefore decided to remove the heat-shrink sleeving and trace all the wires.

I noticed that the wire colours used didn’t seem to tie up with either Lucas wiring colours  or those used by Range Rover. To complicate things, even Range Rover changed their colours!

• Defender V8i Electrical Circuit Diagrams
• Defender MY2002 Wiring Diagram
• Electric circuit diagrams – range rover new uk (2001)
• Rover V8 3946cc-4552cc Overhaul Manual
• British Standard BS-AU7 Wiring colour codes

These are my colour codes:

B  – Black
G  – Green
K   – Pink
LG – Light Green
N  – Brown
O  – Orange
P  – Purple
R  – Red
S  – Slate  (grey)
U  – Blue
W  – White
Y  – Yellow

Having several injected Rover V8 engines, from a 1986 JEE tuned 3.5Ltr SD1 Rover V8 to a 2002 serpentine P38 4.6Ltr Range Rover V8, it became obvious that they all had slightly different plenums, different sensors, idle valves etc. There were different air feeds, crank sensor, fuel regulators….
The list goes on.

Added to which, many of the blogs I’d read, seemed to be from people using non-standard engines taken from a 20 year production span of TVR’s, Landies, Morgans, Boats and after-market tuners. Some were even dual fuel! It didn’t help that acronyms seemed to be the order of the day, complicated by everyone using different ones for the same device.

Part numbers for sensors seemed either thin on the ground, conflicting or obviously wrong. Helpful bloggers had suggested using the same sensor as their Toyota 4 pot, but with a lot of research I found they were the wrong thread or even the wrong type of sensor…… well you get the picture

Rover V8 Megasquirt Common Acronyms

Rover V8 Megasquirt sensors

At this point it, is important to realise I’m just starting out and realistically have barely started. I haven’t had the engine running, so this is a diary of mistakes rather than a ‘How To’.

Air Temperature Sensor (ATS)

I’m using an FAE 33170 (page 81). It basically a thermistor; a resistor that changes impedance with temperature.
Pin1 – Red/Black 0.5mm (Ground)
Pin2 – Slate/Green 0.5mm

• FAE – 33170
• Renault – 77 00 737 572 or 30865366
• Daewoo – 96279856 or 96253552
• General Motors – 96279856
• Siemens- S101431001
• Beru – 0 824 111 007 or ST 032
• Chevrolet – 96279856 or 96253552
• Hella – 6PT 009 104-021
• Volvo – 30865366
• Cambriare – E375084
• Blue Print – ADG07236C
• Fuel Parts – AT1010
• Intermotor – 55703
• Kerr Nelson – EAT019
• Lucas – SNB818
• Quinton Hazell – XEMS600
• 0824111007

I made up a 70mm steel tube for mine to sit in, with a 14×1.5 threaded insert.

The hose outlet is to the Extra Air Valve. I’d rescued the air fitment to the Extra Air Valve from a Megasquirt-V8 AFM tube. For some reason the fitting was 22mm, which was odd because the Bosch Idle valve is 19mm. I therefore bought a pair of silicon 22-19mm reduction hoses.

Coolant Temperature Sensor (CTS)

There are often at least two CTS fitted to a Rover engine. Before the thermostat and after. You want the one marked 6 in the following…

For the CTS I used a FAE 33370

Pin1 – Red/Black 0.5mm (Ground)
Pin2 – Green 0.5mm

• Jaguar – EAC3927
• Land Rover – EAC3927 or ETC8496
• Rover ADU 7130 or ETC 8496
• Saab 74 85 006

Throttle Position Sensor (TPS)

I’m using the smaller TPS, as fitted to a 2002 P38 4552cc Range Rover. The TPS is a potentiometer or adjustable voltage divider.

Pin1 – Red 0.5mm
Pin2 – Yellow/ Light Green 0.5mm (Wiper)
Pin3 – Red/Black 0.5mm (Ground)

• Bosch – 0 280 122 016
• Land Rover – ERR7322

Extra Air Valve (EAV)

From reading the forums, many after-market ECU have idle problems without an EAV.

I’m using a 3 wire Bosch 0 280 140 505

Pin1 – Black 1.0mm
Pin2 – Brown/Orange 1.0mm
Pin3 – Green/White 0.5mm

Lambda Sensor

My Rover V8 set-up has twin exhausts that don’t converge and the Megasquirt MS1 has only one Lambda input. Some modern V8 cars have sensors pre  & post catalytic converters. That’s a total of four. For my one Lambda sensor, I picked a position pre-catalytic converter on the near side.

There is an age long argument raging on the forums whether narrow-band or wide-band is better. It seems wide-band are more sensitive to vibration damage, but have a better measurement range. If wiring is routed badly, then they can be more prone to noise. Narrow band however, seems quicker to set-up and has a longer life span. Many argue as the Rover is so simple, a narrowband is useally adequate.

Then there is 2, 3 or 4 wire. Two wire lambda sensors aren’t heated. Three wire version are heated but the heater shares the same ground wire as the sensor. Four wire is heated and has separate ground for heater and sensor.

What did I chose? It was simple, I had a spare SEAT LEON Cupra 4 wire wide-band heated lambda sensor in a box on the shelf. It had the right thread for my stainless performance catalytic converters, so I’m using it.

Black – Signal
White – Earth
White – Heater
Gray – Heater

Crank Sensor

Many MS1 Megasquirt set-ups use a Ford crank sensor and an after-market 36-1 trigger wheel mounted to the back of the front pulley. The P38 serpentine Range Rover, unlike early SD1 Vitesse’s has a trigger wheel mounted to the back of the flywheel. The 4.0 Discovery is available as a manual. When a 4.0 flywheel & clutch came up for a couple quid, I bought one. When it arrived, it was obvious I couldn’t use it, as it was twice as thick as the SD1 Vitesse. It also weighed 14Kg as opposed to my 8Kg JEE Vitesse one. The intention is to fit the Discovery trigger wheel to the Vittese flywheel and get it re-balanced. This guy’s done it.

The above picture shows the trigger wheel from a automatic flex plate. Whereas I want to use a manual trigger wheel on a manual flywheel.

Apparently, according to this forum piece the missing tooth is at 20° BTDC.

I’m a little confused by that article, as he’s trying to achieve 60° BTDC, whereas I want 50° BTDC

According to this post https://www.diyautotune.com/support/tech/install/install-crank-trigger/ and this image, you need 5 teeth past TDC. That’s 50°, isn’t it?

I’ve got some measuring and phone calls to make

I’ll keep you posted on this one….

Connectors

The above devices use 2 and 3 pin AMP connectors. It’s best to use new connectors and the proper crimp tool. Luckily I still had a pair from my days working for Magnetti Marelli on Renault Engine management design. The same 2 pin connectors are used by the injectors.

I’ve added IP65 water resistant boots and small piece of adhesive heat-shrink. Being sensor wires I twisted them together for mutual inductance (better noise immunity). Where these wires passed close to anything hot, I made sure they were inside heat-resistant sleeving.

All sensor wires were kept in a separate loom to injector and ignition wires. I’ve even got some special RF shield wire mesh to wrap around sensitive wires. Range Rover didn’t feel the need so I’ll only go this far if there is a noise issue.

When looking at the above circuit diagram and from taking apart the loom I’d bought, not much attention had been paid to earth star points or ground loops. When you don’t use star points what you think is 0V (ground) may well be noisy or have a small static voltage upon it. This will cause false sensor readings. The 600volt+ ‘peak and hold’ injector waveforms will be visible on your various readings. If the noise is bad enough, the main micro-controller will simple sit in a permanent reset cycle. The circuit will visually appear correct, and even buzz through OK, but with a decent oscilloscope, the problem will be apparent.

To avoid that, for everything that is ground, run a separate wire back to a single ‘star point’ very close to the battery. If possible, keep the ECU close to that star point. Definitely do not daisy chain earth wires or use the engine block. Keep sensor wires away from Injector and ignition circuits and twist sensor and ground wires together.

Currently the loom is temporarily cable tied, but once I’m happy it will be bound in adhesive free looming tape, non heat shrink sleeving and heat reflective shield.

A set of Magnecor spark plug leads came with the MS1 Megasquirt ecu. However, as you can see, they don’t fit my engine too well. They said Rover V8 – but what model I don’t know.
Therefore, I’ll be making my own 8mm silicon leads.

You’ll see in my wiring diagram I have added wire gauges and Range Rover wire colours. I have also shown multiple wires converging to star points. No daisy chaining here!

Engine run on

In the alternator circuit I’ve added a 1N5402 diode to prevent back voltages through the charge light keeping the ECU powered once the ignition is turned off.

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