I just recently did a swap from a 5.0GI PEFS TBI to 5.7 Volvo Penta the question i ask is, is there a need to change injectors after the ECM has been reprogrammed. I used the old injectors. I am having issues with rpms and backfiring and i want to at least get my mind of, do i or don't i. Fuel pump test shows low at 18psi constant and high at 33 constant. Please advice

You’ll need to double check parts listings, but i believe the volvo penta uses same injectors for 5.0 and 5.7’s with throttle body injection.

I have Volvo’s in my Cobalt. It is the same injectors. Why would you need to reprogram going from 5.0 to 5.7? That is I would be looking. Hook a computer up they don’t lie.

45cid is a lot more air. Air the computer has no idea has been added. Programming will be necessary.