85 TBI Computer - Third Generation F-Body Message Boards

Benjam88 · 02-11-2010, 01:59 PM

Ok, I'm a little confused. I have an 85 Firebird, wich has the TBI 305 in it. And as far as my research and visual inspection goes, it has a Q-jet carb. Now what the f--- does the ECM or ECU, whatever the heck it is, control!? Just my ignition? Then I was reading on another section of the forum about someone messing with the MAF sensor on their TBI. Are there different kinds of TBI? Some one please enlighten me.

John 89 Formula · 02-11-2010, 02:34 PM

They did not offer a tbi v8 in 1985 it was either a carbed motor like yours or a tpi.
the lg4 was the standard v8 they also made a HO version, they are computer controlled
but not sure which ecm the carbed motors used.

Benjam88 · 02-11-2010, 05:02 PM

What does the ECM do on a Q-Jet 305? Just run the ignition?

RBob · 02-11-2010, 05:17 PM

Quote:

Originally Posted by Benjam88

What does the ECM do on a Q-Jet 305? Just run the ignition?

It does run the spark timing, but also runs the TCC lockup (if an auto), the MCS, EGR and AIR(?).

The MCS is the mixture control solenoid on the E version of the Q-jet. During cruise and idle the MCS provides for AFR control, via feedback from the O2 sensor.

RBob.

Benjam88 · 02-11-2010, 10:44 PM

So if I were to get a new motor say a 283 and put my q-jet on top of it and got rid of the need for the spark control and EGR would I need to do anything like burn a new chip for the ECM?