mpping.pdf

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/ TECH / MAPPING /

fast tech

Words: Stewart Sanderson

Photos: Michael Whitestone

WHAT IS

MAPPING?

This month Stu gives us the ﬁ rst of his master class series on the

theory behind mapping and why your Ford might need it.

As most of you will know, what we

actually specialise in at Motorsport

Developments is all forms of

Original Equipment and aftermarket

engine management system

live mapping. Since this is often

thought of as some form of black

art I ﬁ gured it was high time that I

explained in some depth just what

mapping actually is and why you

as an enthusiast need it for your

modiﬁ ed Ford.

Having worked as a tuner for 17

years, Stewart ‘Stu’ Sanderson

is one of the most-respected

names in the business.

A Level 5-trained fuel-

injection technician, in the past

Stu has worked for a Ford Rallye

Sport dealer, a well-known fuel-

injection specialist and various

tuning companies.

Then seven years ago he

joined forces with Kenny Walker

and opened up Motorsport

Developments near Blackpool

(01253 508400, www.

remapping.co.uk ), specialising

in engine management live

remapping, as well as

developing a range of Evolution

chips which are now sold all

over the world.

He’s also jointly responsible

with Webmaster, Petrucci for

www.passionford.com. Started

in 2003, it’s grown rapidly from

a few friends contributing, to

one of the biggest Ford

communities on the web.

Stu’s enviable knowledge of

the workings of modern-day

Ford performance engines

means that every month he’s

just the man to explain how and

why things work, and most

importantly how they can

be improved.

MAPPING? WHAT’S THAT?

Mapping is the term given

to the act of changing an

engine management system’s

calibration ﬁ le.

Now that is all well and good

if you happen to know what a

calibration ﬁ le (or map as it is

commonly known) actually is, but

if like 90 per cent of the motoring

population you actually don’t, then

read on...

BEFORE

STARTING…

THE MAPS

All electronic fuel-injected engines

are controlled by an electronic

control unit (ECU for short), which

is constantly hooked up to sensors

that feed it live data telling it

everything there is to know about

the engine’s dynamic conditions

such as water, air and fuel temp,

throttle angle, engine speed, air

density and manifold pressures.

The ECU uses this input data

in conjunction with a reference

program to see what exactly it

needs to do, such as what fuel

injector duration to supply, or maybe

when to ﬁ re the spark plug, to name

just the two most critical factors.

These tables also tell it when to

do a number of other engine control

related things such as how to idle,

what cam timing to run, what boost

pressure to run the turbo at and

even when to vent fumes from the

fuel tank into the engine for nice

clean emissions, not to mention

when to disable your lovely air

The ﬁ rst rule of working on

cars and using tools of any

kind is don’t ever skimp on

decent protection. Goggles,

gloves, ear defenders,

masks and a set of overalls

should be in your garage.

Use them.

When using power tools,

protective gear is essential

— grinders and welders can

make a real mess of your

soft skin and bone if you get

it wrong.

Never work under a car

without supporting it using

axle stands. A car falling on

you is not something you’ll

be laughing about down

the pub.

Nonsense? No. This calibration ﬁ le or map can be read by the ECU

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Custom chips are based on off-

the-shelf items, but the maps

are tweaked to suit your engine

management system that

is far better than the simple

off-the-shelf calibration but

not at all as accurate as a live

map, so a compromise.

With custom mapping, you

basically start with an off-

the-shelf chip as explained

above, and it is then tweaked

time and time again to get

the best out of your engine.

The tuner would test drive

the car, make notes on paper

as to what rpm/throttle

etc problem arises, and

then modify the map on a

computer, program another

chip, ﬁ t this to the ECU, then

go out again and see what

difference it has made.

This is basically repeated

until the tuner is happy with

the outcome.

This is the option normally

chosen by people with not quite

enough cash to get the car mapped

live, but want more than an off-the-

shelf program for their cherished

chariot. It’s worth noting that this

is quite often the only way a tuner

can work if they haven’t got the

necessary expensive equipment to

live map, so they painstakingly tune

this way.

Some systems cannot be live

mapped, such as Pectel hardware-

equipped IAW P8 systems. Good

results are certainly possible

engine’s planned power output.

Extra air from this point on just leans

the system out as the calibration is

not programmed to see it.

The second big problem with

MAF calibrations is usually created

by camshafts with long duration.

These long duration cams tend to

create a lot of overlap that plays

havoc with gas speeds. This means

the gas speed can drop massively

and in turn, the airﬂ ow meter can

no longer see the airﬂ ow. Worse

still, you can generate backﬂ ow with

high overlap camshaft ﬁ gures and

that means air going through the

mass meter the wrong way!

The MAF meter isn’t direction

conscious, so it presumes the air

is going into the engine and it adds

more fuel... Instant rich condition

and poor driveability are the only

result. Expert mapping can correct

all these conditions and of course

many more we haven’t even

touched upon.

These ﬁ les can be installed

in EPROM form just like the old

days, or ‘ﬂ ashed’ in via the car’s

diagnostic port which leaves no tell-

tale signs of modiﬁ cation. These ﬁ les

are basically programmed all the

same for each type of car/ECU and

engine combination, so if it doesn’t

really do much for your car, it’s

tough. It may work for some and not

others due to the fact all engines

tend to vary somewhat.

2 . CUSTOM MAP

Option two is a custom map. This is

a performance calibration for your

The ECU takes its information from maps, usually

stored on an EPROM or chip. On this 4x4 Cosworth

ECU, the chip has been removed, but would be

located in the lower right-hand corner

conditioning to save bhp when you

need it most.

This information truly does

just scratch the very surface of

a modern engine management

calibration, but hopefully you will

all remember my past articles on

engine management computers

and the sensors that are used to

feed them with the vital information

they require to perform their duties.

We have also covered the sensors

own related ECU maps in the past

too, so if you missed them, please

grab back issues 247, 248 and 249

for a very in-depth explanation of

how these management systems

work. Now, back to mapping...

required, you will have to get the

management system remapped to

ensure it does what it’s supposed

to do with regards sparking the

plugs and delivering fuel from the

injectors — not to mention how

to drive the idle valve for best

idle stability and cold running. In

short, your engine modiﬁ cations

will probably not actually have the

desired effect until you reprogram

the ECU so it knows the mods are

there and what it needs to do

about them.

As a simple and very common

example: if you ﬁ t a nice ported

cylinder head to your car, you can

reasonably expect it to ﬂ ow more air

at high revs due to the new bigger

inlet and exhaust ports, but you

must never forget that this

extra air requires extra fuel

if it is to make any extra

power. In fact, without

the extra fuel you

will normally lose

power due to

the fact you

have leaned out what was once a

perfectly good fuel mixture. There is

of course always the danger that if

you lean it out too far, you will melt

the pistons.

The reason for this is quite simple

but may not be quite as obvious if

you who don’t understand ECUs

and management, so I will try to

explain what happens if you modify

your engine beyond the scope of

the ECU calibration.

about airﬂ ow at all, and can only do

what its calibration tells it to do. As

an extreme example for illustration

purposes let’s look at this scenario.

A Cosworth Sierra had 204

bhp as standard with 8 psi of

boost at around 6000 rpm on

a T3 turbocharger. However, a

Cosworth with a nicely-ported

cylinder head and some sensible

camshafts, allied to a Garrett GT35

turbocharger can make over 350

bhp with the same 8 psi of boost at

the same 6000 rpm. The problem

is, if you were using the same ECU

calibration as the standard car, the

ECU will only inject enough fuel for

204 bhp, as that is all the standard

calibration program is telling the

ECU to do when it sees 8 psi and

6000 rpm.

That is heavily over-simpliﬁ ed

but I hope it makes sense and

illustrates how an ECU can only do

what it is told to do when it was

calibrated. In a nutshell, because we

have changed how much air ﬂ ows

through the engine with any given

pressure, we have to inform the ECU

and program in what is required of

fuel, spark and so on.

The second common system

seen on your Ford is the mass

airﬂ ow system.

This system is a lot better with

regards self-compensation as it

uses a MAF (Mass Air Flow) meter

to give the ECU some idea about

actual airﬂ ow, and not just pressure

as per the speed density system.

With this system you can ﬂ ow a

little more air and still be OK, but

two things commonly create big

problems for it. Firstly, you may

increase the ﬂ ow so much you get

to the point where Ford had no

longer programmed any further.

This is quite easy to do with a good

cylinder head and sensible cams.

This scenario means it goes very

lean up in the power area as the

ECU is of course only programmed

up to a certain limit, above which it

was deemed unnecessary to do any

more programming work as they

were already beyond the production

MY ENGINE NEEDS MAPPING,

WHAT ARE THE OPTIONS?

There are various ways to go about

having your maps changed to better

suit your mods and all vary in both

price and effectiveness.

Emulator (black box on the right) allows you to alter the

maps ‘live’ at the same time as the ECU asks for information

1 . OFF THE SHELF

Option one is to have what we

call an off-the-shelf program. This

is a performance calibration for

your management system that

will remove various compromises

written into the software by the

manufacturer and has basic

performance mods. These include

leaning off excessive rich mixtures

that the OEMs use and running a

little more advance due to the fact

that as an enthusiast you will be

using better fuel than the garbage

they had to program it for, just in

case you put it in there after you

bought the car. Sometimes the rev

or speed limiters are increased or

removed too.

CALCULATIONS

When an ECU calculates how much

fuel to add to the air, it does so in

one of two ways. The simplest is the

speed density calculation using a

combination of manifold pressure,

throttle, air and water temperature

sensors. Now this system is the

dumbest of them all and has no idea

WHY DO I NEED MY

CAR MAPPING?

Since the ECU contains all the

parameters for your fuel injection

system to deliver its goods, if you

make any modiﬁ cations to the

engine that change the amount

of fuel required, or changes

the amount of spark advance

at high revs due to the new bigger

inlet and exhaust ports, but you

must never forget that this

extra air requires extra fuel

if it is to make any extra

power. In fact, without

the extra fuel you

will normally lose

power due to

the fact you

combination of manifold pressure,

throttle, air and water temperature

sensors. Now this system is the

dumbest of them all and has no idea

calibration program is telling the

ECU to do when it sees 8 psi and

6000 rpm.

That is heavily over-simpliﬁ ed

but I hope it makes sense and

illustrates how an ECU can only do

what it is told to do when it was

calibrated. In a nutshell, because we

have changed how much air ﬂ ows

through the engine with any given

Off-the-shelf chips or ﬁ les

are the most common

route to performance

calibration of your ECU

Wide-band air/fuel ratio monitor

is essential kit when live-mapping

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/ TECH / MAPPING /

chip, ﬁ t this to the ECU, then

go out again and see what

difference it has made.

This is basically repeated

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Det cans (usually bolted to an inlet manifold stud) are

needed to listen for detonation while live-mapping

The way they both work is quite

simple to explain:

The left column is the engine’s

load. On the speed density system

this is calculated using the map

sensor, on the MAF system it is

calculated using actual air travelling

through the engine and worked out

as volumetric efﬁ ciency.

The top row is RPM. This is

hopefully self explanatory to you all?

So, at any given load and rpm, the

ECU simply takes the value at that

juncture and uses it to deliver fuel

to the engine. The speed density

system inputs fuel based on pure

manifold pressure as explained

earlier, so if you changed the

amount of air your engine could

ﬂ ow at X RPM and X LOAD, you

would have to change the number

in that table to a bigger number or it

would run lean. Simple eh?

The MAF system is a little more

complex as it is far more intelligent,

but it uses all its inputs to calculate

actual engine volumetric efﬁ ciency

and the fuel table is displayed as a

lambda ratio. We can input a lambda

ﬁ gure as a target and the ECU will

calculate what fuel to deliver to

achieve that AFR.

This all goes wrong if you put

cams in the engine as the airﬂ ow

reading at the MAF tends to go

wrong. It also runs into problems

if you max out the MAF as once

its ﬂ ow is maxed out at 4.9 volts, it

is blind and can no longer do any

further calculations.

So, there you have it, that is just

two of the maps from two of the

systems. If I showed you them all

we would ﬁ ll the next two or three

years’ editions.

However, we are going to look at

these two systems in some more

depth next month, so stay tuned for

part two.

from custom mapping but it is

very hard and time consuming to

perfect anything in this way, as it

is so drawn out and long winded,

not to mention a little inaccurate

by its very nature. A great middle

ground though as long as you use a

competent professional.

the point in the map that is wrong

so you can correct it there and then,

whilst driving the car using that

current data.

This allows you to literally feel

the result of map changes as you

perform them whilst simultaneously

watching the fuelling on your

wide-band fuel monitor, watching

boost levels etc and listening for

detonation. There is no substitute

for live mapping. It is the ultimate

way to tune an ECU. Period.

NEXT MONTH

Mapping in the real world:

what does the mapper actually

do with your car on a live-

mapping day?

3 . LIVE MAP

Option 3 is a live map — the daddy

of the mapping world. Live mapping

is a little like custom mapping but

on a far grander scale. With a live

map you have your chip completely

removed and a laptop is connected

in its place via a piece of hardware

called an emulator.

Once this system is installed

the maps can be accessed live

and altered at the same time as the

ECU is asking for the information.

This means if for example you have

a hesitation at 50 mph in fourth

gear, you can drive the car to that

speed and easily see and access

WHAT DO THE MAPS CONTAIN?

Each system is different but your

average Ford EEC IV and V ECU

calibration contains over 300

end-user controllable maps and

calibration switches. Everything

from fuel and spark to maps that

adjust things based on coolant and

air temperature, as well as battery

voltage and barometric pressure.

Modern ECUs also have adaptive

tables that allow the ECU to learn

how to fuel your engine correctly as

it wears out, meaning less tuning to

be done and less time for the car off

the road.

Every map is dedicated to at

least one individual running factor,

such as spark control, but this

factor may require over 50 different

maps and calibrations to make

it work to the satisfaction of the

original manufacturer. The levels of

accuracy built into modern ECUs

is mind blowing, and the average

aftermarket ECU like Motec and DTA

can only dream of being even close

to as good.

Speed density system: fuel map from an Escort Cosworth P8 ECU

HOW DOES A MAP WORK?

Let’s take two of the most

common maps from two of the

most common systems, and look

at how they work and then it may

give you some idea of what’s going

on within the ECU and how the

information ends up being wrong

after you have tuned your engine.

This list of maps and switches

on a Focus RS ECU is just for

the fuel injectors alone...

1 . Speed density system

2 . MAF System

MAF system: base fuel map from a Focus RS ECU

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