Trash Your Carb and Enter the '90s!
Back when our '70 FJ40 Toyota Land Cruiser first hit the American shore, it was pretty high up on the techno scale. A basic one-barrel carb and a points distributor made for a reliable, yet not too exciting, performance package on the old straight-six, for both the street and trail. While we love our 'Cruiser, we have always yearned for more power, reliability, and throttle response provided by modern niceties like electronic ignition and fuel injection on the factory mill.
Toyota's inline-six cylinder engines in the F and 2F families are based on the 235ci Chevy I-6 built from 1954-62. Most F and 2F engines in Land Cruisers are fitted at the factory with a two-barrel carburetor. The later model in the '87 wagon's 3F-E finally sported factory fuel injection, but the engine was also de-stroked to turn higher rpm for highway use, resulting in less torque for the trail.
In the years we've owned this 'Cruiser, we had made other modifications in our quest for power. To help improve the highway power and poor fuel mileage, we had Man-A-Fre install one of its high-compression, Weber-carbureted, rebuilt 2F engines, with an electronic ignition. This modification improved both power output and fuel economy, but did nothing to cure carb stumbling at angles or over bumps.
Turbo City performed the fuel injection conversion on our pre-smog Land Cruiser using a distributor from Up And Over Innovations to interface between the Toyota engine and the GM computer. Unlike the factory Toyota unit, this distributor doesn't have a vacuum advance since the ignition advance and retard functions are now handled by the GM computer. In fact, the computer thinks it's receiving signals from a '90 V-6 S-10 pickup. Since the GM TBI system bolts onto the intake manifold much the same as a carburetor, the installation is simple. Just replace the distributor, bolt the adapter plate onto the intake manifold, install the TBI unit and a few sensors, add a high-pressure fuel pump, and plug in the new wiring harness and computer. It really is that easy.
After Turbo City finished the installation, we went for a testdrive. The first thing we noticed was that we had to feather the throttle some when accelerating from a standstill, to avoid wheelspin. Once on the freeway, we found that we could pass cars at will. In addition, the throttle response was very crisp. In stock form, the 'Cruiser would climb steep grades only in Third gear. After our Man-A-Fre upgrades, Fourth gear was usable but we were still at wide-open throttle to make the grade. After converting to EFI, we can climb grades in Fourth gear with enough throttle left to pass the slow movers.
After burning a few tanks of fuel, we also found that mileage had increased almost 4 mpg, from an average of about 15 to 19 mpg. However, during this mileage testing we were light on the throttle, while in normal driving we tend to enjoy the added power, so mileage is more like 17 mpg under normal driving conditions. In our off-road testing, the EFI proved even more helpful. Our 'Cruiser no longer exhibits the tendency to flood on steep accents, descents, and especially in hairy off-camber situations. We no longer need to feather the throttle to keep the motor from loading up, and the engine starts much easier, especially in extreme weather conditions. Best of all, the engine will run virtually upside down if we wanted it to, the only limitation being lack of oil pressure.
Fuel Injection Glossary
Coolant Temperature Sensor (CTS)
When the engine is cold, as opposed to warm, the CTS sends a different signal to the ECU to richen the fuel mixture, similar to the choke on a carbureted engine.
Electronic Control Unit (ECU)
The ECU calculates the amount of fuel to be delivered by the injector nozzles based on information received from the various sensors.
Idle Air Control (IAC)
The IAC, located in the throttle body, uses input from various sensors to control idle speed through the ECU.
The knock sensor acts like a microphone listening for detonation. When detonation is detected, it sends a signal to the ECU, which retards ignition timing.
Manifold Absolute Pressure (MAP)
The MAP senses intake manifold pressure, then sends a signal to the ECU. The ECU then adjusts fuel delivery and ignition timing.
Oxygen Sensor (O2 Sensor)
The O2 sensor is installed in the exhaust. It measures the oxygen content of the spent gases and sends the signal to the ECU, which sends the appropriate signal to the injector nozzle to richen or lean the mixture.
Programmable Read Only Memory (PROM)
The PROM is a computer chip programmed with specific calibration information to meet the needs of a particular engine. The PROM can be compared to carburetor jetting and ignition advance curve. The PROM plugs into the ECU.
The throttle body houses the injector nozzles. It has butterfly valves and looks like a carburetor, but has no float bowl.
Throttle Position Sensor (TPS)
The TPS is mounted on the throttle shaft and is basically a variable resistor. When the throttle is closed, it sends a low voltage signal to the ECU. When the throttle is open, it sends a higher voltage signal to the ECU and the fuel delivered to the injector is adjusted accordingly.