Understanding Engines Part IV - what you should do BEFORE you book in for a tune
Getting your project car running is mad, as Marty found out IN THE LATEST EPISODE. So how do you do that?
If you've put an aftermarket ECU in your car, then download the tuning software and watch a few tutorials on how to use it. At bare minimum you should have a look around it to familiarise yourself with it, so you can download a base map and do basic diagnostics on your car once you get it running.
You'll also need to do some set-up so the ECU knows what engine it's meant to run. Telling the brain box the engine's firing order, number of cylinders, ignition and fuelling type (batch or sequential timing), and things like TDC offset angle (or "trigger angle", which you can learn about from Tuning Fork HERE).
Haltech has their software (and wiring diagrams and more) available for free download, so you can get used to finding key information you need, like oil pressure, coolant temperature, RPM, and more - all critial pieces of information you need to be across when you get your project car running. Engines free up after a few heat cycles, while freshly-built engines will need to go through a run-in process before the tuner starts putting the screws to it on the dyno and going for an all-out power run.
Before you book a spot on your local dyno, do some shakedown drives on your car after you go over it and check all the nuts and bolts, and make sure there are no fluid leaks (or fluid disappearing), all your spark plugs and leads are good, and nothing is catching fire or fouling on other parts.
A shakedown also allows you to monitor things like fuel pressure to make sure you don't have a dying fuel pump or ignition system shortcomings that can easily be fixed in a home garage, rather than a dyno cell. This is important because tuners are there to tune your car, not to fix easily solved problems from poorly-assembled projects.
Once your Tuning Fork has your car on the dyno don't think they're just going to mash their PgUp key until you have Internet-winning power figures, "Tuning" an engine is more involved than simply setting a rev-limit and making sure your air:fuel ratio isn't so lean it'll turn your solid piston into a liquid metal.
As aftermarket ECUs get more and more complex, with incredible features like traction control, launch control, bump-in, anti-lag, throttle-blip, nitrous control, flex-fuel, transmission control and more, it adds to the tuning time required. All those features are essentially all units of information which need to be enabled and then have parameters set for each of them, by the tuner.
Parameters are basically the tuner telling the ECU the range of numbers it is happy to see, as a low point and a high-point like a border. For example, a tuner might set the parameters for air:fuel ratio as 10:1 at the low end and 12.5:1 at the top end (on a turbo car, a naturally aspirated car can run leaner).
This is a MASSIVELY simplified hypothetical example just to illustrate a basic point, which is the ECU works within the set range of parameters. Outside that it can go into protection mode (aka Limp Mode).
The more complex engine and car set-up you have, the more time it takes to set it all up, and this is before you get to doing power runs. This is why it is important you should have a basic understanding of how your ECU works, and know your car won't break down every 10 minutes, because you'll be paying the tuner to spend this time working on your car.