I now have a 350 in my GTA. It was a 305 (the ecm is from the 305). After I throw a code 43 (ESC) it wants to die when I let off the gas. I replaced the knock sensor w/ another 305 unit. This didn't help. Should I look into a sensor from a 350, or would that screw w. the computor? This is starting to get very frustrating?

 

If you have a 350 then you need a knock sensor for a 350. The sensors are calibrated for a diff frequency. the comp don't care which one but the harmonics are diff for a 350. some one else can explain it better. but you need the correct sensor!

 

I just posed a question to see what the general concensus is (over in the tech/gen board) about this situation. Its undeniable that the 305/350 knock sensors are tuned for different harmonics. Reason being combustion chamber size will have an effect on frequency etc, also not to mention that the 305 knock sensor has to pick up knock through alot of extra cast iron compared to a 350 knock sensor. But the thing that really makes it get confusing is the knock sensor >> ESC relationship. You have 4 possible combinations
305 knock - 305 esc
305 knock - 350 esc
350 knock - 350 esc
350 knock - 305 esc

The knock sensor will "Detect" and the esc (and i believe memcal?) will "filter" ?

Bottom line is if you have a 350, run the two 350 components..

My question was would a 350 knock (correct application) and a 305 ESC be more sensitive to knock, or would the 305 ESC simply try to filter out the wrong stuff, missing the *real* knock the 350 sensor is sending it...


Anywho thought I'd input