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TBI Fuel Injection Conversion using a GM TBI EFI system!

One of the most popular EFI conversions to older Chevy engines or any engine for that matter is the GM TBI system using the 1227747 ECM. There are many others that will do the same thing but the 1227747 is most well known and documented and will be the basis for this article. Same can be accomplished with any TBI system from mid 1980s to 1995 and all information here will lead you to the right choice!

Best thing to do is go to junkyard and find a motor similar size as yours and get the complete system and parts. Once you get a system get the number off the ECM/PCM and we have a huge library of ECM/PCM by part number listed here:!

Let's go over parts used in a TBI EFI system. As you read through there will be links to more detailed information including all the wiring diagrams needed to make your own harness or rework one from a donor vehicle. For this one we are doing a 1227747 ECM, you can get all the wiring diagrams and files for it here:

TBI system components:

1. ECM = Engine Control Module.
1227747 GM ECM
Has a number like 1227747 is used here.

Inside is the chip
Chip with bin file BCC !

On the chip is the bin file which is the program for running that engine. If you don't know what the four letter code (BCC) like ADSU on the chip are you can look them up with our BCC Bin Find Lookup online:
This was built by one of our members 1Project2many so give him a thanks! You will need the 3 or 4 letter BCC Broad Cast Code or commonly referred to as bin file.

We will have another page for programming equipment, software and accessories needed for changing bin files on chips and another on Tuning! Coming soon!

2. Throttle Body Injection = TBI
TBI Throttle Body Injection
The 4.3, 5.0 and 5.7 TBI's are all the same CFM with 1 11/16th bores. The injectors are different sizes. The 454 is larger with close to 2 inch bores. It is recommended a TBI from about the same size engine to be used in your conversion or larger for high performance built engines.

3. TBI Wiring Harness. Wire harness can be pulled from the factory car and reworked for a conversion. There are also aftermarket options to buy one new already made. Here's an idea of what one looks like when pulled.
TBI wiring harness

Here's the harness you need and the pile of stuff removed.
TBI wiring harness for Conversion

More Detailed wiring information at this link:!-HOW-TO!

4. Coolant Temperature sensor = CTS
CTS Coolant Temreture Sensor
Sensor tells ECM what temp the engine is. Must be mounted in flowing coolant near thermostat.

5. Oxygen Sensor = O2 sensor.
O2 Sensor
You could pull from donor but a new one is cheap. 1 wire sensor will work fine. The universals just splice onto the wire from the harness.

For headers It is recommend a 3 wire heated sensor mounted in collector behind the header, not in the header. They have a built in heater to keep the sensor hot when it is mounted down in the collector.

6. Fuel pumps Lots of choices! You have a choice to modify your tank for an in tank pump or mount one external to the tank.

Here's a picture of an inline EFI pump from Masters Part Number: E8248
EFI TBI Fuel Pump inline
There is also a Carter PN5000 that is similar with fittings and brackets. Other part numbers for inline tanks are: E2000, E2182 and E8248

For high performance TBI engines or TPI/MPFI engines the PN5001 Run an inline clear filter before the pump to protect pump (must have on same receipt for warranty on Carter pump) and EFI filter after the pump.

You can also do an in tank pump
In tank EFI Fuel Pump

The way most new cars come from factory. There are many ways to do this. Here is a link to a write up using one of the best factory in tank pumps available at junk yard for cheap. Parts are easy to come by at any parts store. Greg aka greags78cam did an excellent article on how to do this here:

7. Fuel pump relay
Fuel Pump Relay
From donor vehicle with the harness.

8. Power relay can use same as above or many options.

9. Adapter plate for the TBI you can make one or buy one.
Spread bore
Speadbore TBI adapter

Square bore

2 barrel- Holley
Two Barrel Carburator to TBI adapter

10. Distributor with EST = Electronic Spark Timing.
Small Block Chevy EFI distributor

The small cap EFI distributor already has the EST mounted inside. If your converting a GM engine you can probably just buy one and drop it in.

This distributor can also be made for any engine by grafting a GM upper onto any make motor lower half of distributor by a machine shop.
TBI EFI Hybrid distributor!
Here's a write up on how and reference to a shop that has been doing these for 10 years.!

For the fuel only conversion you will retain your stock distributor but will need a special filter to run between your ignition and the computer. Except no one sells them anymore and when they did you could do a ignition conversion to have fuel and spark control by ECM for same money. You can use tach filter output of MSD box to trigger ECM injector firing!

EST Module= Electronic Spark Timing
EST module

11. MAP = Manifold Absolute Pressure sensor.
MAP sensor
This senses the change in manifold pressure. it usually is mounted on a plate, bolted to the intake manifold. You can modify the plate and remount it on the manifold or make a plate and mount it on the firewall.

12. On some ECM they have an IAT Incoming Air Temperature sensor in the air cleaner or MAT Manifold Air Temperature sensor in intake manifold.

13. ESC = Electronic Spark Control.
ESC Module
This sends the signal from the Knock sensor to the ECM to reduce the timing if it hears a knock.

14. VSS = Vehicle Speed Sensor.
VSS sensors
VSS sends the ECM the cars speed. Jags that Run (JTR) sell an aftermarket VSS that screws right into speedometer cable Good for smooth deceleration and also for cruise control input on later systems. Can be made to run without one but much better with! Many transmissions also have a VSS built into them. Some cars and trucks with electronic carburetors have a VSS built into speedometer in dash board.

15. EGR-exhaust gas re circulation solenoid.
EGR control solinoid
If you need to run emissions.

15. Coil
EFI coil
From the stock GM TBI system is super hot spark and incredibly reliable. Can use others if you want.

16. MAT = Manifold Air Temp sensor.
MAT sensor
Used on some engines to measure air temperature in intake manifold.

17. IAT = Incoming Air Sensor.
IAT Sensor
Used on some engines to measure air temperature on air coming into throttle body.

These systems are easy to convert to a carbureted engine and replacement parts or diagnostics can be done by considering the vehicle as a 1987 to 1991 (up to 1995 for some ECM/PCM)

These pages will always be updated with new information ! For more information check out links to forums.

Written by EagleMark and Members of

Copyright 1999 2012 TBI and EFI conversion!