Need help figuring out my 1987 Trans AM with Lg4 CODE 41
 

Hi there I need help figuring out what engine code 41 is and how can I go about making it go away on my 1987 Trans Am with the carbuerated 305 LG4 engine.

This code does not make my SES light illuminate but when I jump pins A and B or use a snap on MT2500 scanner I discover that the code 41 is stored. My scanner says code 41- EST circuit- No distributor reference pulses to the ECM at specified engine vacuum.

I have a new ignition module installed as well as a new MAP sensor. The Map sensor is connected to a vacuum port on the carb. I thought replacing both of these would have helped but not look in clearing the 41. Can anyone advise?

Thanks

Re: Need help figuring out my 1987 Trans AM with Lg4 CODE 41
 

Verify that the port on the carb used for the MAP sensor is not a timed port. Typically the MAP should be connected directly to a fitting on the intake, but a port on the carb is acceptable IF the port is true manifold vacuum, as in those ported to the lower well in the throttle body.

Re: Need help figuring out my 1987 Trans AM with Lg4 CODE 41
 

Have you tried disconnecting the battery and resetting the ECM? Just to see if it comes back.