"Not Detected"
 

I know you said you replaced the part.. Sounds like the ecm is not getting a reply from the inquiry to the sensor. Perhaps the sensor has failed and it's telling you that. Or there is a bad connection and it won't act right until it has the correct sensor voltage. The quickest way but not cheapest is to get it from a dealer obviously - Regarding the push in connector.

Although, depends on who did your program etc... I've seen some weird stuff with that.

so you think it isn't detecting the KS at all ? could be ... a scanner in real time would show that.

Does this 502 MPI ECU have something like a "Guardian Mode" as does the Merc 496 PCM555 ECU?

My post was assuming that you had "seen" the "not detected" from within the scan tool. If not connected, or bad connection etc... it will tell you somehow either way.

Don't forget that scanners often fool you or just point you in the right direction.

Good luck.

from what I understand the ecm looks for a signal from the sensor and it cant get one so it alarms, I dont know if it retards the timing at that point or not, I wasnt in a place to pull out the scan tool. it did start running like crap after the alarm went off so it felt like maybe the timing was retarded.

I will replace the sensor and try and find a connector at a GM dealer, Merc only sells the harness complete.

I bought the boat with the ecm reprogrammed but I agree, I wouldnt mess with it again, not sure what I gained except I can run 5100 or 5150 without hitting the rev limiter.

Thanks