Engine Tuning, Remaps, Fuel Saving

What is Remapping?

Most modern vehicles contain an ECU (or Engine Control Unit) that is a small computer which controls how the engine performs. it decides based on information from sensors and the drivers inputs how, much fuel and the timing of ignition or injection or both.
Vehicle manufacturers de-tune the engine by setting the software on the ECU to safe levels.
This is done due to the manufacturers having to sell their cars all over the world, this means that the software settings on the ECU must take into account different climates, laws & restrictions and varying quality of fuels. Not to mention irregular servicing and poor quality lubricants and filters.
Vehicle remapping is basically the modification/replacement of the manufactures default software on a vehicles ECU, to optimise the settings for our temperate climate, good quality fuel supply and regular servicing.

How is it done?

A vehicle remap replaces default software on the ECU, overwriting it with new software which can be programmed to optimize the cars overall performance. This is known as vehicle remapping because the ECU is essentially a program that controls how the engine is controlled. When your car is remapped, the tuned software is plugged into your cars serial port (or OBD port) which then overwrites the engine map with the new version to enhance engine performance. The ability to flash directly through the OBD has brought the tuning industry on leaps and bounds, with constant development on the engine now being much quicker via the flash process.
It has its drawbacks however as now anyone can remap your car, not just the specialist tuning companies.
Every couple of years the vehicle manufacturers improve the security of their software, which prevents remapping via the OBD port.
This is what is happening right now.
For newer vehicles the ECU has to be removed then opened and boot pins connected to the ECU circuit board. This is not for the faint hearted, and requires specialist up to date equipment.

It cannot be done with cheap clone tooling.
This will once again remove the cowboys from the industry, for a while at least.

Maths Test ( Ford Transit P0121) Pedal Position sensor circuit performance

Maths Test

A Ford  Transit was presented with a fault code stored for accelerator pedal performance.
DTC P0121- Throttle/Pedal Position Sensor/Switch 'A' Circuit Range/Performance.

Information systems suggest the causes for such a fault are;
- Faulty throttle position sensor
- Throttle position sensor harness is open or shorted
- Throttle position sensor circuit poor electrical connection
- Faulty Engine Control Module (ECM)


The easy option is to replace the pedal, but we prefer to test the component plus the power, ground and signal wires before condemning any parts or control modules.
It may take longer than picking up the phone and ordering the suspected part but it is a vital step in the diagnostic process.

The easiest way of testing the complete circuit is to use an oscilloscope.

Most older pedal position sensors use a variable resistance track that changes the voltage sent back to the module which is converted into a pedal position.
This method uses an analogue signal, which must be converted inside the module into a digital signal.

Some newer vehicles employ a digital sensor which can be utilised by the module without any further processing of the signal.
The sensor output is a fixed frequency variable duty signal which can be tricky to interrupt using the oscilloscope.
Check out the scope trace of the pedal signal.

This one test shows that the power and ground is good as well as proving the change in pulse width. 

The problem is checking the smooth transition from the idle position to Wide open throttle.

The use of a built in maths channel to display duty cycle is very useful.

To display the Duty Cycle on a Pico Scope you need to select Tools> maths channels>Create>Advanced>Duty>A>Next>Next>Next>Finish>Ok>

You should then end up with a trace like this;

It is now much easier to analyse the performance of the pedal sensor. Note the smooth transition from idle to WOT.

Diverter Valve VAG

We are still seeing plenty of diverter valve (DV) failures here at Gotboost.

The original factory diaphragm can crack under high boost pressure and create a massive boost leak. The new OEM valve features an upgraded piston type design modeled after the more expensive aftermarket units. This is the perfect solution for anybody needing an upgraded DV that does not want to void their factory warranty with "aftermarket" parts
The DV is a pathway for boost when it is not being used by your engine. Whenever the throttle body is closed, such as during gear shifts or deceleration, the boost needs an escape route or the pressure will build up and slow down the compressor. This can cause turbo lag or even damage the turbo.
A Blow Off Valve (BOV) or dump valve performs the same task as a Diverter Valve, but instead of returning the boosted air back into the intake, it vents it to the atmosphere making a distinctive noise.
We can replace your DV with the uprated part for just £76.25.

Boost got you under pressure

A Honda Civic Type R with a Jackson racing supercharger conversion was presented with major running problems.

It runs with a Hondata ECU which has proved itself to be very reliable and more than capable of running this conversion many times.
So why was this one idling at 2500 rpm and almost un-drivable?

With such a popular conversion, it was easy to find information.
This provided us with base maps, tuning specifications and hardware requirements.

The first thing to do was check for fault codes, however there were no codes stored.
So we connected the basic logging equipment to the vehicle and attempted to drive it on the dyno.
The result was extremely poor fuelling and massive overboost.

We now had a problem. The hardware was not compatible with the vehicle.
A change of supercharger pulley diameter was required.
Once this was completed the boost pressure was now within acceptable limits. But the car was still not right.

Looking at the map stored on the ECU, during testing it appeared to have some very poor calibrations.
The answer was a base map from a similar specification car. This is then fine tuned to suit the vehicle. In this case reducing the knock counter at certain load and rpm ranges by trimming the advance curve.

The result was night and day. The car now pulled like a train and recorded a very healthy 188BHP at the wheels or around 240BHP at the flywheel.

Why is it so hard to sell the concept of training to the UK automotive aftermarket?

Given the complexity of the modern vehicle, you would expect technicians to require regular updates about the advances in vehicle technology.
So why is it so difficult to persuade garages to train staff?
Why do technicians not want to advance their learning?

Most garages are aware of the skills gap they face, but they opt for the ostrich approach and ignore the problem. A common mistake is buying diagnostic tools and not taking advantage of the training that is provided. Instead the technician muddles on, doing what he always did. Getting what he always got.

I had a set of tyres fitted recently and I watched the tyre fitter closely.
He didn't remove the wheel weights before balancing the wheel, this resulted in a large number of weights being fitted without achieving dynamic balance.
He used an air gun to tighten the wheel nuts, then checked the torque using a wrench which clicked immediately meaning the wheel nuts were already over tightened.

When paying the bill, I asked the manager (his badge said he was anyhow) about the short comings in the procedures used by his staff. His reply was they needed training.

Great news, so I left my card, and waited for the call. After a week or so I called the garage. Offered my services and reminded the manager that a few hours training would make the garage more efficient, profitable and improve customer satisfaction. He response was he had no time for training.

I wonder how they are getting along with run flats, tyre pressure monitoring, and 4 wheel alignment seeing as they couldn't balance a tyre and tighten the wheel nuts correctly.

Vectra Light failure

Modern cars have the ability to monitor circuits and report errors when they are detected.

Modern light systems have the ability to warn the driver that a circuit failure has occurred with a Malfunction Indicator Lamp. The driver can then take the car to the workshop for diagnosis and repair.

The owner of one such vehicle was certain that he faced an expensive repair when the lighting circuit MIL illuminated on his Vauxhall, but when he checked the lights he could not find the one not working.

A quick code read suggested a fault with the rear left brake light circuit. However the brake lamps appeared to be working when the pedal was pressed. The light cluster was accessed and the lamps checked. The nearside brake lamp had indeed failed.

This led to a number of questions from the puzzled driver.

So how did the car know?

Why are all the lamps the same?

Why did the lamp appear to work when the pedal was pressed?

The answers are linked to how modern lighting circuits are controlled. The use of vehicle networks has reduced the number of fuses and relays by as much as half. But every circuit must have a form of protection, in the case of modern lighting it is the control unit that monitors the current drawn by circuits. It can then switch the circuit off if it detects a fault. It can then elect to use another lamp and circuit to replace the faulty one. In this case the brake light circuit was inoperative so the side light circuit was used to perform the task of the brake light. This is possible as the lights are controlled using a pulse width modulated signal. The brake lights require full intensity so have a pulse width of 100% but the side lights only require around 25% of the 21Watts available. By switching the circuit 278 times a second the 25% duty cycle is seen by the lamp as a 3Volt supply. (This is what you would read on a multi-meter) The 21 Watt lamp illuminates at around a quarter of its intensity, or 5 Watts the same as a tail light. The means the same lamp can perform the task of tail and brake lights. Using just one lamp makes economic sense as it reduces inventory.

The control unit sends a signal to the lamps and checks the circuit before it is used. Here the brake light circuit is being monitored every 10 seconds. The voltage is pulsed so fast that the filament does not even start to glow. This is how the control unit can detect a fault before the circuit is used.

Using an oscilloscope you can check the current draw during the circuit check. Here the time base has been reduced to 1ms per division. The red trace shown indicates a current of 9 Amps on a brake light circuit. This has to be a fault. Or is it?

Once the lamp is switched on (100% duty cycle) the current measured is around 1.7 Amps. This is normal for a 21 Watt lamp.

Watts law current = power/voltage

21/12 = 1.75 Amps.



Same lamp same circuit. Different current draw, this is because once the lamp heats up and starts to glow its resistance increases. Try it for yourself with a multi-meter, measure the resistance of a cold 21 Watt lamp. Then use Ohms law to check to expected current flow.

Remember Amps = Voltage/resistance.

Lost your spark

Modern ignition systems have evolved from contact breaker or points systems. If you look carefully you can still see some of the DNA of these systems in the latest systems fitted today. So is it reasonable to assume that some of the tests performed on older ignition systems can still be performed on these modern systems?

The answer is yes and no. Some of the old tests can still be performed when there is suitable access but many of the tests focused on the High Tension or secondary side of the coil. However access to the high tension side is often only possible after removing the coil pack, you can use an extension between the coil and the plug to test the HT outputs. These tests can be performed with an oscilloscope or a spark tester.

Some (older) readers will remember measuring dwell angles. Testing the LT or primary circuit, has changed little since the days of points, a test lamp can still provide quick and effective proof of circuit integrity. However an oscilloscope can provide extra details that can lead to more effective diagnosis. With an oscilloscope it is possible to analyse the current draw as well as the control signal/voltage at the same time. The reason why this is so important becomes clear when you consider how the modern ignition system is controlled.

Modern ignition systems consist of various inputs, logic and outputs. Inputs are from sensors such as crankshaft position, (engine speed & position) Manifold absolute pressure, or Air Mass (load) and knock sensors (abnormal combustion).

The logic or ECU, crunches the numbers and selects the correct ignition advance, dwell period as well as monitoring the circuit for faults and providing the circuit protection.

The outputs are the low tension circuits, fault codes and malfunction indicator lamp. Or in the case of amplified coils a signal to switch the amplifier and often a conformation of ignition signal back to the ECU.

These control signals can be an internal function of the ECU or in the case of amplified coils a square waveform that is used to switch the primary coil. The on time of the coil is controlled by this signal. The output stage allows current to flow through the primary windings when the voltage is present and stops the flow of current when the voltage drops to 0V. This ‘dwell’ can be measured much like on the older systems. The yellow trace is the control signal and the blue trace is the current flow through the primary windings. 

The cursors are measuring the on time or dwell, in this case 3.16ms. A typical value for a running engine. Notice the coil has reached around 5.5 Amps. Then current in the circuit is limited. The primary coil windings have low resistances, between 0.2 and 0.8 Ohms. This allows a rapid build-up of current, and can reach 60 Amps if left unchecked in around 40ms. The current in the circuit is dependent upon the voltage so to ensure good saturation the ECU can compensate for low voltages. The chart shows the current build up in a coil of 0.2Ω for both 12 and 8 Volts.