Default map or base map?
Every new Haltech ECU arrives with a default map already loaded. Nothing in it is zero: every table and setting holds a sensible generic value and a realistic shape, so you can see roughly what each map should look like. That alone saves a huge amount of typing compared with building a calibration from a blank file.
A base map goes a step further. It's built for a specific engine, with everything that's known about that engine already filled in. What's left is the part that's unique to your car.
| Default map | Base map | |
|---|---|---|
| Comes from | Preloaded in every ECU | Loaded for a particular engine |
| Engine details | Generic | Displacement, cylinder count, firing order and trigger setup filled in |
| Fuel and ignition tables | General shapes | Axes and values suited to that engine, kept deliberately mild |
| Best for | One-off, experimental or unusual engines | Common engines, where one already exists |
If you're building something oddball, start from the default map. If your engine is popular, chances are a base map exists. See free base maps for your ECU or ask us and we'll point you to the right file.
What a base map sets up for you
Take a GM LS2 as an example. Loading its base map fills in the engine capacity, cylinder count and firing order, and configures the trigger system to suit GM's factory crank and cam sensors. Those are exactly the things the ECU can't guess, because a default map has no idea what engine it's going on.
What you still need to check
This is the part people skip, and it's where most first-start headaches come from. Work through this list before you crank:
- Ignition. The coil count will already be right. If you still run the factory coils, the base map's coil settings are fine. Upgraded coils need their own coil settings and charge (dwell) times entered.
- Injectors. Injectors are one of the most common upgrades. If yours aren't stock, enter the new injector data before the engine runs.
- Inputs and outputs. The Functions page in the base map assumes a particular wiring layout. Compare it pin by pin with how your car is actually wired.
- Extra sensors. Oil pressure, fuel pressure, extra temperature sensors and wideband O2 usually aren't set up in a base map, since nobody knows which inputs you used. Assign them yourself.
- Fuel and ignition tables. Look through them. They'll be sized for your engine but deliberately conservative.
If a base map exists for your engine, open it before you wire the car and look at the I/O assignments. Wiring to match the map means far fewer changes later, and fewer chances for a mistake.
What a base map is good for, and what it isn't
A good base map should get the engine running so you can:
- check for fuel, oil and coolant leaks,
- bleed the cooling system,
- confirm the sensors read correctly, and
- move the car around the shop.
What it shouldn't be used for is load. The tables are intentionally tame, but they aren't tuned for your engine's airflow, fuel or ignition needs. Before the car sees real throttle or boost, it needs a tuner and ideally a dyno session so it makes the power it should with the reliability you want. Our dyno tuning basics and don't blow your engine articles explain why.
Common base map problems
| Symptom | Usually |
|---|---|
| Won't start, no RPM signal | Trigger sensors wired to different inputs than the map expects, or the engine isn't the variant the map was built for |
| Starts rich or lean straight away | Injector data still at stock values after an injector upgrade |
| Weak or missing spark | Upgraded coils with the base map's stock coil settings |
| A sensor reads nonsense or nothing | Input assignment in Functions doesn't match your wiring |
FAQ
Can I drive on a base map?
Only gently, to move the car and do the checks above. Put real load on it only after it's been tuned.
Is a base map from another car's tune a good idea?
Someone else's finished tune can be a useful reference, but it's matched to their parts and wiring. Treat it like a base map: check every setting against your build.
What if there's no base map for my engine?
Start from the default map and fill in the engine, trigger, ignition and injector settings yourself. If you'd like a second set of eyes, book a free consultation. Want more reading? The knowledge base covers each setup screen in detail.
