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Injection details, Upgrades and ECU Re-chipping

v8 engine Rising rate fuel pressure regulators
RPi Family Eprom-Chips
Identifying your injection type
Dealing with fuel maps
Ecu Chip Identification
Injection System Hardware upgrades.
Air-mass Meter upgrade from 3.9 / 4.2 Howire to 4.6 Gems. (20AM)
Tune resistors & more.
Setting Air Mass/Flow Meter & Throttle Pot.
Upgrading 3.9 Air Flow Meter to 4.6 (wiring)
Customer comments
Morgan link
The Rover V8 'Hot Wire' type Injection systems

Hot Wire Type Injection.

Carbon fibre trumpets, 48mm

Here you can see the ported intake & the Carbon Fibre 48mm Trumpets.
Mainly used in the late 80s and most of the 90s

This system is the most common we find now, is easily upgraded and its efficiency can be improved by re-mapping (re-chipping) as the std fuel map used by Rover is very much a compromise. Not only on the vehicle it was originally intended for, but more-so when this Land Rover engine is used in smaller vehicles or other applications.

< ---- Carbon Fibre 48mm spread bore trumpets, on ported and matched intake. It's just one more place where the rest all fall down!!

Adjustable Fuel Pressure Regulator

Control of Basic. Fuel pressure ( 'Rising Rate' is not required on the later 'Hot Wire' system)
Firstly, this valve has an adjustable fuel pressure affected by the movement of an adjustable screw on the crown of the unit.

New power boost valves are pre-set with a maximum fuel pressure of 2.5, 3.0 or 3.5 bar, depending on the vehicle in question, and similarly (to the original valve) the fuel pressure is reduced by 0.5 bar approx. at idle. There the similarities end.

You have total control over engine fuel pressure and the ability to set base mixture perfectly for your individual engines requirements.
Complemented with the Optimax or Tornado chip, this has to be the best of options.

An assortment of fuel pressure regulators. Fitting is very simple.
Also available for many other EFI vehicles.

Available for £POA (Rover), also available for many other Fuel Injected, Standard , Fast Road or Competition engines.

Fuel Maps & ECU Chipping.

Far more important than you may have considered.

Fuel Mapping

Full control of the fuel map is contained within this innocent looking Eprom (Chip). It contains all the fueling rpm & fuelling load map information and instructions required to run your engine.

To understand better how it works you must understand that although your engine needs to run at varying RPM, it also has an extra permutation such as 'Engine Load'. Load can be considered as the difference between part throttle cruising and full throttle accelerating or pulling.
ECU Chip
Optimax Chip and (scrambler) "sorry" no copying It.
When you are in part-throttle cruise driving, the fuel mixture using Optimax or Tornado will run slightly lean giving you the best possible economy.
When you demand higher & higher load performance, such as under hard acceleration and load pulling, the Optimax and Tornado will run richer and give you the best possible performance, both without losing sight of efficiency.
With over 120 load/rpm adjustments, the Optimax and Tornado are streets ahead of any competition (most of which just target more bhp with more fuel dumped in at high rpm).
Optimax Chips 3.9 Economy, efficiency and getting it right for your vehicle's needs. £ POA
Tornado Chips 3.9 4.2 & 4.6Essential for all 4.6 upgrades or higher performance 3.9s or 4.2s. Power without losing sight of efficiency.

How do I fit the Sagem ECU chips?

Below you will find descriptions of how to find your Sagem ECU depending on what vehicle you have, a link to the video we have posted on YouTube showing how to fit them and also a PDF file of the instructions supplied with our chips.

OK so for starters you need to locate your ECU, simple on some vehicles a little bit more trick on others if you are not sure what you are looking for as there can be some many (such as P38's :-)

Note before removing any ECU, ensure the keys are removed from the ignition, then disconnect the negative terminal on the cars battery. When reconnecting the battery ensure that the keys are out of the car as many modern alarm systems will lock there doors as soon as the battery is connected.

The P38 Range Rover 1994 - 1999
Located in the engine bay, behind the right hand headlight there is a large plastic cover over the battery. Behind the battery you will see the main wiring loom disappear into another black plastic container with a lid held down by two phillips screws. The Sagem ECU is located in here, remove the two phillips screws then remove the three multi plug connectors.

The 4.0 litre Morgan +8
Located in the engine bay on the left hand side of the car, technically above the passenger footwell.

The Defender 90 50th Anniversary
Located in the engine bay on the drivers side of the car, the ECU is under a plastic white cover which is held in place with one bolt.

The NAS Spec Discovery 4.0 litre
Although we have supplied many ECU chips for these we have never needed to ask a customer where his ECU is :-) We believe it would be inside the car under the dashboard however please let us know if we are incorrect.

How do I fit the Hotwire ECU chip?

Below you will find descriptions of how to find your Hotwire 14CUX ECU depending on what vehicle you have and also a PDF file of the instructions supplied with our chips.

OK so for starters you need to locate your ECU, simple on some vehicles a little bit more trick on others if you are not sure what you are looking for as there can be some many. However in all cases the 14CUX ECU is black with one large multiplug connector plugged into it.

Note before removing any ECU, ensure the keys are removed from the ignition, then disconnect the negative terminal on the cars battery. When reconnecting the battery ensure that the keys are out of the car as many modern alarm systems will lock there doors as soon as the battery is connected.

Range Rover Classic
You will find the Hotwire ECU located under the right hand front seat, so that's the drivers seat on right hand drive vehicles.

Discovery Series I
This is normally located by the A pillar in the footwell on the right hand side of the car and is hidden by the plastic kick panel that removes simply by pulling away the door seal.

Morgan +8 3.9 and 4.6 litre
Located in the left hand foot well, the best way to find this is to look in the passenger footwell and then look up as it is on the underside of the bulk head. It is sometimes a two person job to remove this as the bolts holding it in place need to be accesses from under the bonnet to stop them from spinning.

MGR V8's
If your MGR V8 has air conditioning (as most do) then your ECU is located in the left hand footwell behind the air conditioning unit. If you look closely you will be able to see the lower edge of this and also the small 8mm bolt that fixes the holder of the ECU in place.

Located in the passenger footwell behind the battery, this should be easy enough to find and whilst in the area of the battery check for terminal corrosion as this is something quite common that we find in this area.

Marcos and Kit cars
As the Hotwire system was also used on many Kit Cars as it is such a good fuel injection system it might be necessary to chase the main loom from the engine to find where your ECU is. We have found on some Marcos's the ECU is buried deep in behind the dash board, often not actually fixed in place but surrounded by dash wiring looms.

Identifying your injection type

Air flow/mass Meters
There are basically three types of production Rover V8 Injection systems with some variations. This section is designed to help you decide what injection system you have, so we can advise of the best upgrade for you.
The following information is for all systems pre 4.0 and 4.6 gems, this being the third option it is covered elsewhere on the web pages.

Gems upgrades 'Click here'

EFI Flapper (air flow meter

Which one is yours?

If you are a little concerned about what type of injection system you have, identifying the Air flow/Mass Meter will determine it for you. This applies to all EFI V8s except the later 4.0 and 4.6 models, these use the later 'Gems' Engine management.

EFi Hot Wire Air Mass Meter

See below for Gems type 4.6 Air Flow Meter

4.6 and 3.9 Air Mass Meter

Almost all including TVR, offer big capacity upgrades to the 3.5 & 3.9 Efi engine but what's the point when it still has to breathe though already restraining Rover stock parts. As well as the obvious lacking in the Air Mass Meter, there are major upgrades available for almost all other injection system areas

'Special Tornado' 3.9 to 4.6 conversion chip

With the same goals in mind as with the Optimax chips, the Tornado chip is not only suitable but essential for all 4.6 conversions, delivering fast road performance with endless torque. Special Hybrid variants of this chip are available to produce efficient fuelling on engines up to 350bhp and in some case beyond, so whether you want high efficiency - High Torque - or you are not happy with the power of your TVR 500, then the Tornado is available to fully satisfy your requirements.

Bhp and Torque gains through the entire rev range

With power figures like these, don't underestimate the value of a well set up and configured engine.
dyno graph
You will notice from this 4.6, Stage 3 Tornado Engine Dyno, that we have not only big gains in torque and bhp, but at no time do the power figures drop below that of the original engine configuration. So no losses, all gains and very substantial ones at that!

Injection System Hardware upgrades.

Seeking maximum Power? Or perhaps Your TVR 500 just doesn't reach The 'Mark'?

The following pictures (below) show additional improvements that are available for achieving maximum power from the standard Rover Injection induction systems.

Although not necessary for standard or most fast-road engines, these induction enhancements would be essential for higher performance rebuilds and will vastly improve the power attainable at engine revs beyond 4500rpm, allowing the V8 to climb up to 7500rpm & beyond 350Bhp.

You've seen Jeremy Clarkson's Grin, as he exits the cockpit of a TVR 500, but he ain't seen nothing yet!!

injection injection injection
Extensively ported manifold & shortened trumpets Big throttle body plenum 70, 75 or 78mm Close up view of the shortened & polished trumpets
injection injection carb and fiber
Modified & ported injection manifold (top view) Flowed, shortened & polished trumpets (top view) Carbon Fibre 48mm spread bore trumpets, on ported and matched intake
 The total cost of these performance improvements is from as little as £675.00 (excluding special Tornado Chip) & can be utilized with both 'Gems', 'Hot Wire' & 'Flapper' type injection systems. All parts are supplied on an exchange basis, and an upgrade to carbon fibre trumpets is an additional £65.00

V8 Fuel Injectors.

 3.9 injector
At last Now Back in Stock.
Shown with protective caps fitted

Brand new 3.9, 4.0 4.2 and 4.6 Injectors, less than 1/2 list price. One of the main reasons for poor fuel consumption on all 3.9, 4.0 and 4.6 models is old injectors. At only £240.00 (You change you plugs every 6,000 or 12,000, when did you last change your injectors? For a set of 8, these have to be the best value anywhere.

(recon Injectors also available)

Some ask us how can we possibly make things better than the original Rover Spec.
Well, just take a look at this 3.9 intake, and perhaps you may start to understand just how easy it is.
Intake mainfold and gasket Marked to show poor machining
Stock Cylinder head ports with intake gasket shown This shows just how badly the std. engine is port-matched & the exhaust is not much better.

Airmass Meter upgrade from 3.9 / 4.2 Howire to 4.6 Gems. (20AM)

To get the best from you higher Performance upgrade, it is worth noting the big advantages of up-grading the Air flow/mass meter. As you can see from the upgrade on this TVR 500 Griff, the 3.9 Airmass meter (retained by TVR) has a very restricted aperture and should be upgraded for maximum power benefit.

TVR 500 Griff.
TVR 500 Griff.

20 (Gems 4.6) Air Mass Meter Fitted. You can see the substantial air flow advantages of this upgrade.
Under bonnet 3.9 & 4.6 Airmass meter
Gems 4.6 & Hot Wire 3.9/4.2 AMM.

There are many improvements available for the Injection hardware on all the systems, and it is attention to detail such as this that helps gain the power claimed but missed by most users of this engine.

Suitable for all type of Rover V8 injection systems. Further upgrades and power figures for all our highest spec injection systems and large capacity engines can be found here (Engines 4.6 to 5.2) If you are really serious about power, this is the page you should visit.

The maximum potential of the Rover Injection System and other induction methods is always pegged below 400bhp due to the limitations of Rover original head castings. Ask about 'Ultimate Big Valve Heads' if you want to push the limits beyond comprehension, but beware, these heads start at £1,250.00 per pair.

Tune resistors & More
And for the more Technically minded.

Tune resistor info (for those that want to know)

Tune resitor

Please note that although the information below is still correct it has been updated here.

All Efi 'Hot wire' systems will incorporate a Tune resistor. Its function is to make sure the vehicle runs the correct Fuel map in the ECU for Cat or Non cat vehicles. If you cannot locate yours the following may be relevant.

There were definitely some EFi looms made after 1990 with the tune resistor taped inside. From 1990 onwards (14CUX systems) they all have to have one, but you've got to find it first!

If there is no tune resistor, then the vehicle will run on the default 'Limp Home' map. Where the resistor is fitted externally, it will be where the relays sprout out of the loom, not by the ECU. PRC9060 is a normal ECU with the regular set of maps in it.

A Green tune resistor (green referring to the color of the wires) will always give a non-cat tune, and White is always a cat tune. By the way, the default (Limp Home) tune is a cat map, so this usually makes a non-cat car run very rich.

You need to run the correct tune resistor to get the correct fuelling from your ECU and you need to re-chip all Hot wire ECUs if you have upgraded your engine spec. in any way. Especially if increasing capacity or changing cam, and even for stock engines, the Optimax chip will refine your efficiency, economy and performance.

For those 'Even More' technical. A tune resistor should be connected between pins 5 and 27. The wire colors are Black/White and Black/Grey (where the first color is the primary color, and the second is the trace). The Green tune resistor value is 470 Ohms, and White tune is 3900 Ohms. Ordinary 1/2 Watt resistors are just fine, although the original is a Metal Oxide 2% item (which I always use anyway). In this location I sometimes use a 1 Watt resistor, because the larger physical size makes them easier to handle.

Setting Air Mass/Flow Meter & Throttle Pot.

Any competent garage should find this very easy indeed.

Switch ignition on but do not start.

You require a digital multimeter to carry out the adjustments.
westfield setup
Air Mass Meter
westfield setup
Throttle Pot

Find the Throttle pot on side of plenum. There are three (3) wires coming from this unit to a multi plug. Do not disconnect. Wire colors are Red, Green, Yellow. Red from volt meter to red wire of pot. Black wire from volt meter to Green of pot. Volts should read .33 to .35 volts if not, loosen the two (2) screws that hold it in position and turn it to get the correct voltage. If you cannot get the correct voltage setting, undo and remove the throttle pot, make the fixing holes elongated and you will be able to get the right voltage.

Please note that the following air flow meter settings should be made when the engine is warm.

The air flow meter wires can be accessed by pulling the rubber boot carefully backwards along the cable. Under here you will find the following wires. Red with Black trace = Sensor ground, Blue with Green trace = air flow signal, Brown with Orange trace = Ignition live 12 volts and Blue with Red trace = CO trim value. A digital multi meter should be used and connected to the sensor ground and CO trim value wires. The values that you are trying to achieve are below and these are adjusted by the screw on the side of the airflow meter.

Air Mass meter setting (non cat). The voltage reading on the CO value here should be between 1.0 and 1.5. If you have the Tornado ECU chip fitted then 1.5 volts should be aimed for.

Air Mass meter setting (cat). The best setting for the CO value here is 1.8 volts.

When setting your Throttle potentiometer and Air Mass/flow meter, you should also check the resistance scaling, using an Ohms meter and checking from highest to lowest resistance, smooth scaling is essential for the correct basic workings of all these units.

All High performance and big capacity Hot Wire V8s should consider upgrading to the 4.6 Air Mass Meter as shown above.

Upgrading 3.9 Air Flow Meter to 4.6 (wiring)

Ensure your ignition is switched off.
Disconnect the Fuel Injection ECU
Disconnect and remove the old Airfolw Meter, then fit the new one in place.

Cut off the old airflow meter plug (4 wires). Tape back the Blue/Red wire (CO Adjust signal) as seen in picture, which will not be connected to the new Airflow Meter.

Put the new rubber connector boot or silicone seals over the wires.
Crimp the new connectors onto the wires.

With reference to the diagram on the right, make the following connections to the new Airflow Meter (Note: Incorrect connection will destroy the airflow meter and invalidate the warranty)
1 - Brown/Orange (+12 Volt Ignition Switched)
2 - Blue/Green (airflow Signal)
3 - Red/Black (signal Ground)

Copyright Mark Adams


Remove the rubber seal inside the ECU plug, then remove the two securing screws. Then slide back the connector shell.

Please make sure that in the next step you find the correct wires (by tracing them back to the pin number on the plug).

Please see the diagram to the right for relating to the pin numbers.
The arrow on this diagram represents the order of the pin numbers.

Identify the following wires in the ECU plug
(as seen in pictures)
Blue/Red on pin 22 (CO Adjust)
Red/Black on pin 25 (Signal Ground)

Connect the CO Trimmer between the above two wires (see diagrams to the right) by tapping into them.
Do Not cut either of these wires.

Plug in the ECU and turn on the ignition, but do not start the engine. Adjust the CO Trimmer until a reading of 1.3 Volts is obtained across the terminals. (Note: higher Voltage gives higher CO)

Switch off the ignition. Insulate all connections. Reassemble the ECU connector, and re-fit the ECU.

The CO Trimmer may be located inside or outside the ECU connector shell. Outside gives easier access for idle CO adjustment.

The Engine will not run untill matching ECU EPRom chip has been installed.

Customer comments

Defender 90 4.6

We fitted the RPI chip to our modified Defender-90, which it fitted with a warmed over 4.6L Rover V8, and it made it come alive! It also cured the rich running problem at cold start-up that it had since new.
Michael Green@West Coast British. USA.

Follow up:-
Just returned from eastern Nevada, our trip was some 1500 miles over the weekend in the 4.6L D90; Chip made huge gains on and off road... cruised at 90+mph on freeway with no trouble and pedal left over... did over 100 for fun! In the mountains where 4th was the key, big gains yet again! Great set up now. MG

Range Rover Optimax Upgrade

After having a good drive back to Northampton last night, the differences made by the chip became very apparent, and the car has been measurably improved in both performance and driveability.
Cheers, Bill Barclay. Scotland.

TVR Tasmin 400se 1991 - 4.0L

Chris, Just a note to let you know how the EPROM change went. History of car: TVR Tasmin 400se 1991 - 4.0L hotwire. Big Valve Heads and uprated camshaft (origin: Wedge Automotive, but spec unknown). The car is also fitted with big bore 3" exhaust. The car was over fuelling and was generally uneconomical. It was subsequently found to have the 4.5L EPROM in the ECU - obviously to try to increase fuelling after mods. I purchased one of your Optimax chips and am generally pleased with the results. It has cured erratic idle problems and given me an increase in mid-range torque. It also makes the engine a lot more flexible - with the ability to pull from lower rpm.

Range Rover Discovery Chipping.

I've now had my Disco at SAC (www.steves.co.za) who must rate as the most reputable tuning house in SA:
Here are my findings as measured at the wheels with 2 wheel dyno by SAC on both occasions:
With 3.9 + Unichip + 245/70/16 tyres: 82KW @ 4300 / 250Nm @ 3300
With 4.6 +Unichip + tornado chip +245 / 75 (!!! NB !!!) / 16 tyres: 111Kw @ 4300 / 307Nm @ 3400 Above figures were measured at 1500m above sea level. SAC found the TORNADO was running a little lean at low RPM and a little rich at high RPM but acknowledged that it was one of the best chips they've come accross.
This (and timing) was corrected with the UNICHIP. Before they tuned it, it was idling rough, and backfiring on overrun. Now she idles smooth, and the backfiring is limited only to a very abrupt "parp" immediately after releasing the throttle - must be for less than 0.25 seconds. The rest of the overrun is clean. My conclusion is that I am very satisfied with the result and I feel I got my money's worth. PS: I'm already saving for a 5.2 for the HSE - yet to be purchased ;-)

Kind regards Philip Lochner South Africa.

TVR 4.3 Griff. T Wolk. Germany

Hello Chris, First of all I wish you a happy and succesfull new year. I plugged in the Tornado chip and did a little test driving. The road conditions were not good the last few weeks so I could not run at full power, but I felt that the engine ran much better at low revs. A rather uncomfortable behavior which in german is called "Schieberuckeln" (when the car starts rocking after RPMs fall under 1500 and the throttle is closed) is nearly eliminated. I look forward to the improvement of the RPM range above 5000...

Reply.Assuming no engine component wear, this may be down to you ignition system, Want to upgrade it next?

Prices do not include local EU.Tax.(VAT).
Prices & stock are subject to change without notice. Information and advice, as always, is free.

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