C4 - code 42 (Electronic Spark Timing)

[tmcorvette]

I've got code 42 (EST) in my '88 'Vette. Is anybody here who knows what should I check? Please help me...

 

[8388]

This could be a couple of things. make sure all your connections are clean and tight. The system will advance the timming untill a knock is picked up for a reference point. If one is not detected you could wind up with a code 42. Clear the ecm by disconnecting the batt. and see if it continues.

 

[scorp508]

I typically get this when I forget to plug the EST back in after setting base timing.

 

[tmcorvette]

Thanks, I've checked all connection and the problem is still alive. Maybe do I have to change ignition modul?