Did the 730 swap on my Firebird and now I have code 33. High voltage at map=low vacume. My scanner says the map is holding like 4.33v constantly even at 4000 rpm. I tried the map sensor off my camaro and nothing changed, I thought maybe the new map was bad. Hunted for vacume leaks too, wondering if that was causing the low reading but none were found and vacume gauge said I was holding a steady 19. I checked all the wiring also and its all fine. Need to get it running fine so I can pull motor. Help please......

 

Make sure the vacuum line to the MAP sensor is on a full time vacuum port. If you have a Mityvac pull down the MAP sensor while checking the scanner reported MAP value.

If it doesn't change the MAP ground may be open, or the ECM may be bad. The MAP get +5v from the ECM, ground to the block and ECM, then the signal goes to the ECM.

RBob.

 

I went through and checked all my connections. I have two map sensors and two 730 ecms. Tried both ecms and both maps and same results. Now the map is holding steady at only .78 v at idle and at like 4000 rpm. This is irritating.