I'm getting code 43 and can't find what the problem is. The code stands for ESC failure or something. Can somebody please help?

 

Yes, code 43 is ESC (electronic spark control) failure. This is on the '91 L98 with port injection? 1227730 ECM?

If so it can be caused by a number of things. Depending upon when the SES is thrown can help in diagnosing the issue. If the SES comes on during normal driving it is either a wiring issue or the sensor is bad. remove the connector from the sensor and read the resistance (ohms scale) from the center pin of the sensor to the engine block.

The resistance should be around 3.9 K ohms (3900 ohms). If off then the sensor is bad. With the connector on and the igniton switch in the on position, read the voltage at the sensor (will need to probe it). It needs to be between 2.4 and 2.6 volts. If not, then remove the connector and read the voltage there, it needs to be 5 volts.

If the SES comes on during heavy acceleration, then the forced knock test is probably failing. Some calibrations, no all, will try to force knock under WOT conditions. If it can't then the SES and code 43 is set.

RBob.

 

Yes, this is for a 1991 TPI car. Well, the SES lights up as soon as I start the engine. Where is that module located?

 

The ESC module is mounted on the MEMCAL inside of the ECM. The knock sensor is low on the engine block, passenger side. In front of the starter mounted in the drain hole.

RBob.

 

The problem was the knock sensor. So much better now. It really feels strong now. Thanks a lot!