Also my computer is reading o2 sensors and I don’t have any plugged in.
Hello Obs89,
Don't know how familiar you are with the stock '97 EFI setup, but in
simple terms it is set up to run in 2 modes:
* The 1st is "Open Loop", where the computer comes up with the
proper ignition advance & fueling based off of what's in the software
tables, indexed after the computer reads how far you've pushed on the
gas pedal, the vacuum(absolute pressure) inside the intake, etc.
So yes, in a healthy engine bay, the computer can & does run the engine
without any input from the O2 sensors. And depending upon how cold it
is and how long it takes the engine to get up to normal operating temps, this
happens for the first ~90 seconds > 5 minutes.
****
BUT, once the computer senses that the engine is up to temp AND the
O2 sensors are toggling high & low, we go into closed-loop operation
and the real benefits of an EFI-managed SBC come into play. (Benefits
defined as max efficiency & driveabillity with minimum possible emissions.)
This is why you are getting feedback to fix the missing O2 sensors asap.
IF you are living where you are no longer subject to emissions-testing,
then you
still need to at least replace the front (2) O2 sensors so that the rest
of the system can then be successfully troubleshot/sorted out.
And if you need to pass emissions then you will need all (4) O2 sensors
operational. (The rear sensors are there to monitor catalytic converter
health.)
To recap, yes these engines will run with missing O2 sensors. They
just won't run as well as they should. Consider adding in those O2
sensors, and then use this setup to learn what it takes to dial in
the computer system to your powerplant. (I'm inferring that you
are planning on an improved engine?)
What you will learn in the process will pay big dividends down the road.
There's no feeling quite like driving a sharp running truck that *you*
sorted out. It's the feeling of being in control of your GMT400 destiny. :0)
By the way, welcome to the forum. I look forward to what you discover.