Diagnostics

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Applications

PC/Laptop/Apple Mac:
For some ECUs it will take you straight through to a website based application, for some ECUs you still need to download a separate application.
The applications work with Rover MEMS 1.3/1.6/1.9/2J/3 ECUs, RC5 Airbag/SRS module, and Bosch 5.3 ABS pump, with live data, data logging, and fault code clearing.
PC Applications

Android Phone/Tablet:
The Android app works with MEMS version 1.2, 1.3, 1.6, 1.9, 2J ECUs and RC5 Airbag/SRS module.
It is completely free and always will be
Go to Android app in the Google Play store

Apple iPhone/iPad:
These are not possible to support due to Apple policies. You are not allowed to plug in and use normal USB cables, only apple certified adaptors.

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Diagnostic help

Get in touch if you need help, or send a data log export to me, but here is some general info to help check for issues.

1) First step would be to go and check for fault codes.

2) The next step would be to just turn on the car ignition and look at the values for the sensors.

The battery voltage should ideally be just over 12v without the endine running

From cold the air temperature sensor and coolant temperature sensor should give a value somewhere close to the current ambient air temperature.
With the engine still NOT running but with your foot on the throttle a little to open it, the MAP sensor should show approximately/almost 100kPa - normal atmospheric pressure - check the weather for an up to date pressure reading if you are unsure. This value will be slightly lower if you are at high altitude (still 90+).

You can test the throttle sensor now - slowly press the throttle all the way through its range while checking the value reported - it should increase as you increase the pedal. If the value sticks or jumps (the wrong way even) at any point then there could be a problem with the TPS sensor.

3) It is then a good idea to start the car and watch the readings/values of sensors as it warms up from completely cold..

Important first value to check - the MAP sensor value should have dropped a lot with the car idling, if it still shows near 100kPa then you probably have a bad vacuum leak somewhere that need investigating. A car will not run at total vacuum but a normal idle vacuum range might be 30-60kPa (let me know if you think differently and I will update). At full throttle the MAP reading will approach the current atmospheric pressure - approx 100kPa as above.

The battery voltage should be approx 14v with the engine running and alternator charging

If any sensor is completely stuck at a certain reading then it is likely disconnected or has a wiring issue, or is completely dead. The sensors have default values set when the computer cannot read them e.g. Coolant temp defaults to 59 degrees C, Intake air temp defaults to 35 degrees C, Lambda defaults to 435mv.

When starting the car from cold, the coolant temperature should gradually increase from approximately the outside air temperature up to approx 90 degrees C depending on your thermostat.

The air intake temperature should slightly increase as the engine and engine bay warms up, it should start from around the outside air temperature.

The lambda reading should be rock bottom/0 at first start up, and start to rise until it gives out proper readings within about 30 seconds. Once it starts giving readings, it should swing either side of the middle value - it should look fairly random but spread across the whole range of possible values. If it stays in one place either high or low then it is potentially dead. Bear in mind that other issues could also be causing a genuine constantly high or low lambda reading.

The idle error shows how far away the car is from its intended idle RPM, this should be relatively low - under 50 rpm error would be good. If this error value is high then don't just adjust the idle setting, something is not working normally that needs fixing.

Sensor issues -> symptoms
Incorrect MAP reading - poor/hunting idle, incorrect fuelling - more fuel is added for high MAP readings (ECU thinks throttle is open)
Incorrect air or water temperature sensor reading - incorrect fuelling - more fuel is added to account for cold engine temperature (needed for genuine cold start)
Incorrect lambda reading - incorrect fuelling and emissions - lambda sensor tells ECU to add/remove fuel in order to hit a stoic mix

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Technical info

Are you a programmer? For more in-depth technical info look here

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