Hey guys and gals I’ve posted on here before so please refer to that thread for more detailed backstory. Long story short, I blew my original powerhead about a year and a half ago and got it replaced with a fully dressed powerhead but I’m still using my old ecm. Ever since the new powerhead was put on its idled like crap. I’ve replaced and/or checked everything you can think of that would cause a rough idle to no avail so now I’m on to the electrical system. I noticed with the new powerhead, the analog voltage gauge only shows about 10 volts with key on and around 12 while idling. It used to show 12.7 with key on and 14+ while idling. Voltage measured at the battery and alternator still show 12.7 and 14+. Why would the same gauge show less with a new powerhead? Also, I’m looking at the print out of stored faults taken from the last shop I took it to. It shows like a snapshot of every sensor every time a fault happens. Every fault that’s happened since getting the new powerhead shows the voltage between 12.6-12.7 on the snapshot. It seems to me that even though the battery and alternator are producing the correct voltage, the ecm somehow isn’t getting all of it and causing weak spark which causes misfires at idle. Does any of this make sense? Any idea what would cause this? Thanks!
