Can a code 43 make the car run poorly? When I pull up to a light my car surges then can stall out. I have been 2 footing it when I have to stop lately. I pulled out a 43 but nothing else. Should be knock sensor? Car is an 91 L98 auto

 

I believe the lack of an active detonation sensor and ESC system will cause the ECM to revert to the lookup tables for timing. You'll lose fuel mileage and performance in that mode. Better start checking out the system.

 

The '91 tpi doesn't have an ESC module.
I would replace your knock sensor.
Sound like your timing is being retarded.
I don't think it should cause your surging problem though.
I had a knock sensor go bad.
Was getting a code 43 and the car had no power.
It would barely pull out of its own tracks.

 

The car still has plenty of power actually. I know this isnt the original engine and the knock sensor is the wrong one. The guy who I bought it from said he was going to get it replaced before I picked it up but never did. I dont even know if it is hooked up or not. I will have to check when the snow melts. I did a datalog but I dont really know what I am doing or looking for. Maybe someone could evaluate it for me? Could that provide some insight?

 

Correct. The ESC system of a '90-up eliminated the separate control module and incorporated its function to within the ECM. It still works the same, however.