Most cars on the road today have sequential injection systems. The older cars had bank or batch-fired multi-port (MPFI) or throttle-body injection (TBI) systems. Although all injected cars can be easily converted with a propane injection system, TBI systems generally require a fumigation (mixer upstream of the TBI) system in the conversion. In some cases, TBI engines have been converted with LPG multi-port injection conversions.

Many conversions done in the 1980s and 1990s involved Impco carburetion equipment adapted to TBI and MPFI engines with Dual Curve controllers. Autotronic Controls Corporation has since closed their Dual Curve division and Dual Curve controllers are now obsolete as well as Technocarb's EFS600 fumigation conversions. Technocarb generally recommends their SVIS Injection Conversion Kit for most older EFI engines including TBI. Since the SVIS controller does not change ignition advance, someĀ  engines may potentially be optimized for propane with Timing Advance Processsors.

A concern many people have with propane conversions is the availability of propane. Because all EFI conversions are bi-fuel, the motorist never runs the risk of being stranded from running out of fuel. The only risk is that the propane station on the trip is more expensive than the motorist's favorite station at home. In Canada, propane motor fuel stations are extremely common, comparatively more so for cheap fuel than in the USA. Many propane stations in the USA are not set up for refueling cars so their prices are often more expensive than they should be. To find a refueling station in your area or for your trip, please visit the following directories:

For trips through locations you haven't been before, it's a good idea to always call ahead to check prices, hours, and availability.