Hey hows it going? Well striaght to the point I have an 86 trans am that i swapped a 305 for a 350. It has a cam, lifters, and push rods and only about 40k. the ecm is still 305 stock. I get a SES for code 43, but the weird thing is that it only comes on when i decide to drive a minor bit crazy by pushing the throttle to fishtail around a corner. But then when i turn off the engine and turn it back on it runs fine. Any ideas?

 

damn, hope you get a response, im on the same mission..

 

Change your knock sensor, they're different from a 305 and a 350, that should solve your problem. Let me know how it works for you.

 

FYI, in the case that you are curious... you're seeing a forced knock check. RBob describes it in a thread about patching code for burning your own chips:

https://www.thirdgen.org/forums/post...06-post34.html

Essentially, if you hammer it, the ECM will perform a forced knock check, trying to get the engine to knock. If it can't (because you're running high octane gas, the car is tuned very well, your knock sensor is bad or incorrect, etc.) then it puts you in limp home mode. Turn the car off, turn it back on, code is gone, it all runs fine. It is an annoying problem to have.

I had this happen a lot on my car when my fuel injectors were too large for the chip I was running. As Brisk said, it could be your knock sensor from the 305 not working properly with the 350. If that's not it, there are other possibilities for this code; search for code 43 and you'll come up with a ton of information on the boards.

 

Well I found out my knock sensor wasn't to blame at all. It was in fact my ecm. I swapped out ecm's and wham bam my car is on the road with no problems now lol

 

Hi. I have the same code and it is driving me crazy. Here's my situation. Car turns on and idles perfect. Once on the road that's when things start to go weird. When accelerating the car shakes at around 40mph, then goes away then shakes again at around 55-60mph and then goes away. It shakes as in it cannot accelerate any further but then can. Today it didn't want to go past 60mph. The SES light turned on and it has code 43 stored "Electronic Spark Control Failed". I've replaced distributor cap and rotor, and module recently. I replaced the coil about 4 years ago. Any suggestions? I have a 1988 5.0 TBI Camaro by the way.

 

OK. I guess I will replace the knock sensor and see if that fixes the issue. I'll keep everyone posted.