I just helped a friend do a 305 tpi to a 350 tpi swap on his 91 z28 and the car runs like crap it cuts out at around 4k rpms and feels alot slower then the old 305.

do we need to change the ecm or just the prom chip what about the injectors will a adjustable fuel pressure regulator make up for the small 305 injectors if so what should the pressure be set at???

if any one has done this swap and knows what the problem is please help us thanks

 

I did this used bigger injectors, lt-1 and changed the knock sensor, also worked the manifold over. Everything worked fine, and made a nice difference. Is the problem ignition related?? or are you sure it is fuel related?? Do a search as many have used the stock injectors and raised the fuel pressure others have simply ran the stock stuff. Sould be a ton of info on a search. If you cannot come up with something contact me direct and we will hash this around-Good Luck- Les

 

why did you change the knock sensor???? Not sure what the problem is we are using the stock 305 ecm and tpi intake setup i have been told that we need to replace the prom chip by afew people and i have also been told the ecm and prom need to be replaced along with the injectors.

 

The 305 and 350 knock sensor are different seems as if the 350 makes more or different noise and will cause the smaller motor to trigger earlier. Did you test the tune up and have you found out whether it is ignition or fuel related?? Not many have had the need to replace the ecm or chip but go on to the forum and read about the results a new chip can be a asset but only if you are not battling problems to start with. Les