i just swaped my 305 tpi engine with a 350 engine that was only tbi now when i run the car it has alot of power when its cold but nothing when it warms up i also put on edlebrock 3" exhaust with 3" cat all oxegen sensers
in place had the car checked at local garage with an error code 45 esc.do i need to change the ecm for this motor?
i did use the top of the 305 ie.the tune port injection intake

 

You will need to use a L98 prom in the ECM for it to work properly, also I believe the L98 ESC module and knock sensor.

 

What year 305 TPI?

 

the 305 was the origanal motor 1991 the 350 was 1990

 

That's a "speed density" system, that needs to know what it's operating. So, it needs PROM tuning for a 350, such as the L98.

The knock sensor module is built into the ECM. I've heard conflicting stories about the knock sensor itself being different between 305 & 350.

 

will i need to buy a chip or can the one i have be programed or will an after market one work with the exhaust better thanks for the help pullin my hair out here

 

Any of those options, as long as your current configuration is part of the chip choice input.