I have just got my heads back from the machine shop, put it all together and ran great for 2 days. Now I get the code 43. I have a decently built 355 with a stealthram, P&P heads, headers, MSD 6AL, MSD coil, custom PROM, T56, etc. The definition of the code 43 is kinda blurry. ESC circuit prob, or Knock sens. prob, or too much retard in timing. Or something like that. I have checked and double checked my MSD wiring, All grounds are on the back of the heads, timing at 10* ATDC with connector disconnected. Don't know what else to do. It runs like crap when the light comes on. HELP!!!!!!!!!!!!

 

I have just got my heads back from the machine shop, put it all together and ran great for 2 days. Now I get the code 43. I have a decently built 355 with a stealthram, P&P heads, headers, MSD 6AL, MSD coil, custom PROM, T56, etc. The definition of the code 43 is kinda blurry. ESC circuit prob, or Knock sens. prob, or too much retard in timing. Or something like that. I have checked and double checked my MSD wiring, All grounds are on the back of the heads, timing at 10* ATDC with connector disconnected. Don't know what else to do. It runs like crap when the light comes on. HELP!!!!!!!!!!!!

 

did you check the wiring to the knock sensor itself? although i don't have the procedure in front of me, that is probably the issue. do a search and you will find how to check it. first thing to do, though, is disconnect it, turn the key on, and see if you have power in that wire to the sensor. i believe it's supposed to be 4-6 volts. if you do, then you need to check the sensor itself.

 

Hope the 10 deg ATDC is a typo and it's really 6-10 deg BTDC. Otherwise it may be failing the knock diagnostics (where it adds a crapload of timing until it detects knock, then says it's ok if the sensor did pick that up).

It's likely something else though, like a disconnected sensor or whatnot.

 

One quick note... If your knock sensor ends up being bad, use a GM REPLACEMENT!!! the factory AC DELCO... trust me on this

 

Ya sorry meant 10 BTDC