i have a new setup. 350 .040 over (357) with patriot vortec heads 2.02- 1.60's. howards cam .504-.510 with 280ish duration. ported intake and plenum. runs and drives but pops a code 43. i replaced the distributor and checked timing. and the knock sensor is fine. my question here is could this be bc i do not have a prom chip for this setup?

ive been trying to troubleshoot for far too long now. im pretty much completely stumped. any thoughts or ideas would be extremely helpful.

 

Did you get the right knock sensor for a 350? My buddy swapped his 305 to a 350 and still hasn't put the 350 knock sensor in yet (or at least to my understanding they are calibrated for a specific engine displacement because they detect certain acoustic sounds to compensate for detonation) and when we were datalogging it, it was trowing a code 43. Not sure if that is the problem or if it's because we unplugged the esc to set the timing and didn't unplug the battery to reset it, but I thought the 8746 reset it after every time the ignition is turned on...

 

i have the right knock sensor. but i didnt know you had to disconnect the esc to set the timing?

 

Well that's what a guy told me on fsc, what truth it holds I don't know but I figured it was so the esc doesn't retard the timing while your getting the mechanical timing right, but if it is knocking and retarding the timing I suppose you should try and get the knocks out to begin with yah know.

We changed both the knock sensor and escm, did you change the esc as well on the drivers side firewall?

 

i didnt know that. maybe thats part of the issue. i will try that first thing in the morning. im gonna buy a new knock sensor too. thank you soo much for your input

 

Yup, sorry I couldn't be of any more help, figured I'd trow that in there though.

 

ok well it has alot of trouble idling on its own. but i drove it today and it felt great for the first minute or two. really smooth. but then it started getting a little choppy. like its runnin too rich.

 

My initial spark timing happens to be at 10dA timing so it cannot provide 17dA. It will idle at 10dA. Connecting the ESC it will move to 17dA.

 

Absolutely....

 

It is the EST/BYPASS connector that gets opened to set the timing. The ESC system is separate from the EST system.

seannana, when does the ECM set the SES for the code 43? Is it about 10 seconds after start up, or is it during heavy acceleration?

RBob.

 

thanks for the feedback guys. this issue is soo frustrating.

RBob- it usually sets about 10 sec after starting. it happens most of the time but not everytime. and sometimes it will come on for a sec then go away.

 

Oh alright I gotcha, thanks for clearing that up RBob. I guess the guy was confused.

 

The code 43 after 10-seconds is from a bad connection or bad knock sensor. The ECM ('7730 w/$8D), measures the resistance of the sensor via the ADC. If it isn't within the proper range, then something is wrong.

Some times due to the age of our cars, the connector is failing. Other times the sensor is failing. The issue could also be that the wire between the sensor and ECM has rubbed though and is shorting out.

Best bet is to start at the sensor and check the connector.

For troubleshooting, the ECM applies 5 volts to the sensor through a resistor (3.9 K ohm). The sensor then pulls the voltage down to about 2.5 volts. That 2.5v (plus/minus a tolerance) is what the ECM is looking for. The sensor should also measure about 3.9K ohm.

You can also measure the voltage on the wire, then on the wire while jumped to the sensor.

RBob.

 

similarly I had purchased and installed the wrong Knock Sensor. (KS) It was a 305 KS stuffed into a 400 block. Changed sensors and the codes magically went away....(no doubt into another spacial dimension or parallel universe... only to come back with the next Star Trek or Avatar movie release)


Even though the 350 sensor may not be ideal for a 400, it's much better than a 305 KS woul d be..

 

while going through the harness i noticed alot of splices and repairs. so i think im just gonna buy a new harness from painless and go from there. that way if i still have the issue ill know for a fact its not in the wiring. and ill have a nice clean look under the hood. i will post updates after the install. thanks for all your help and time so far

 

I found the problem. The knock sensor wire was damaged on the inside. Just got it all back together today. I thank you all for your input and help.