My Buick Odd-fire TBI is run by a closed loop system.
This breed of Fuel Injection is old by the most current fuel injection standards, being used on GM luxury cars in the 1980s and Chevy Pick up trucks and Vans in the early 90s.
But it offers many advantages to a 1960s era engine.
There are FIVE sensors involved in the system :
1) Crank Position Sensor a.k.a. Crank Trigger
The Crank sensor I adapted to the Buick Odd-fire is a Holley aftermarket device. It is composed of an aluminum wheel with three magnets in it that are spaced at 120 degrees around the wheel. This wheel with magnets is about 6 inches in diameter and bolts behind the crankshaft pully. A magnetic pickup is mounted on s bracket off of where the mechanical fuel pump once was mounted. The pick-up is adjusted .040 of an inch from the wheel and generates a micro voltage signal that the computer reads everytime a magnet passes by the pick-up point. This is needed by an odd-fire engine, but not for an even-fire Buick V6.
On the even-fire Buick V6 the distributor signal will work, but the odd-fire Buick V6 distributor signal is irregular and confuses the computer.
The Crank Trigger signal tells the computer when to tell the injectors to squirt gasoline-- and is one of the inputs that regulates how much gasoline enters the engine at various RPMS.
2) O2 sensor--
Mounted in one exhaust pipe, reads the amount of oxygen in the exhaust and is adjusted to maintain the gas to air mixture at about 14 to 1. The O2 sensor is a generic GM sensor.
3) MAP sensor--
The Manifold Absolute Pressure (MAP) sensor sends a signal to the computer to adjust gas to air mixture based on Intake manifold vacuum.
4) Throttle Position sensor (TPS)
Sends a voltage change to the computer as the throttle position changes-- runs mixture during open system (cold) operation, and acts like an accelerator pump squirter during closed system operation(engine warm)
5) Coolant Sensor
Tells the computer when the engine is warm enough to switch over to closed loop from open loop.
To tune the system I will first get a scanner and monitor the outputs of each sensor at various engine loads and RPMs-- and take notes. A new chip could be designed to specifically handle any special needs revealed by the scanning notes.
I am running a 1975 odd-fire vacuum controlled HEI
I am using an odd-fire engine because I like the way they run with a sentimental lump-lump-----lump-lump
The system I built is 100% usable on a Buick V6 even-fire 3.8 engine- so if I blew my odd-fire engine, I have a 1987 even-fire in the garage waiting to go as a possible replacement.
My vehicle ( 1983 Nissan 4x4 PU ) by law will have to run a closed loop system in order to be smog legal in Denver, Colorado.
One other good WWW on an older 4x4 vehicle getting TBI is found at ---
As long as your carburator runs good on your engine--- maybe just keep a carb...
You could buy a lot of gasoline for the price and effort of fuel injection. Changing
to an electronic fuel control system for me was a legal requirement imposed on me by
the legal powers that exist in the Denver Colorado Metro area.
Once upon a time I just swapped engines and away I went-- but that was when I lived in a non-smog controlled area of the
I am of the opinion that the odd-fire Buick V6 is worth rebuilding and running in a light 4x4 vehicle.
It has some high torque, light weight, and compact size properties worth preserving---and I love that
old Buick odd-fire Lumpy-lump rythum.
I will get some pics up on the www within a couple of weeks