- An Android phone
- A car with an OBD-II port (you very likely will have)
- A bluetooth OBD-II module. This costs around £6 / $10 and are easily available e.g. on eBay. I personally have a cheap elm327 version as in the link and it works perfectly.
Torque (https://play.google.com/store/apps/details?id=org.prowl.torque) has been around for years. You may already know about it. The free version gets you started, the paid for version is definitely worth getting for all the extra features.
You will need to find your OBD port in your car. They are generally located in the driver's footwell, or behind the ashtray, or under the centre console by the handbrake:
Plug the OBD module in, pair your phone to it and open Torque. Make sure you turn on faster communication in the settings as the ELM327 adapters support this. Also it's worth setting up your vehicle profile to get accurate MPG, horsepower and 0-60 times.
From there, this is what you'll get:
In Realtime Information you can set up your views like so:
Here, I've chosen a theme which goes more with my Skoda Octavia, then I've added the following dials:
Vacuum / Boost. My car has a turbo so I can see that it's boosting correctly. I know that on overrun (decelerating in gear) it should be pulling a good vacuum. Mine seems to read -14 PSI which shows I don't have a vacuum leak in my intake, essential for a turbo car.
Revs. Nice to see alongside other items.
Throttle. Shows how much throttle the engine is being given from my electronic accelerator pedal. Interestingly, my car never goes higher than 89%, this is probably OK but I'll follow it up.
Coolant temp. Most dashboards show 90 degrees C as soon as anything over 70 is read, so the needle isn't going up or down all the time. The car needs to know the actual temperature and measures it, so it's useful to see if it starts climbing above normal, you can remedy it early.
AFR. This is the Air to fuel ratio and I have chosen c - called for and m - measured. These 2 should be fairly close and show that what the engine is trying to get with the mixture, it is actually getting. Mine is a bit unstable at tickover which is a symptom of the VW TFSI engine which gets a clogged up intake, disturbing clean airflow into the engine.
There are loads of others you can put on there on multiple screens including GPS speed, car measured speed (to see how accurate your odometer is), lots of engine readings, misfires, emissions, calculated horsepower, 0-60 times etc.
There are also other features such as reading and clearing fault logs, which can save you a fair whack by not having to pay a garage to do the same thing.
When used with a phone in an in-car holder, this app is priceless. It's the equivalent of the car having hundreds of extra gauges and dials showing you everything what's going on. You'll get to know what stuff normally says and what they mean, and over time if something starts reading differently, or you see a wrong value, you'll potentially head of expensive repair bills.