Hello everyone! I posted this in the hybrid and conversion section but got no responses. I feel this may be a better section to post in. I’m having a bit of an issue with my swap on my 76 C10. After years of working up to it, I finally swapped in a 6.2 L9H with a 6l90. For the most part, everything is great. The only thing I had happen was a start and immediate stall condition. I ended up tracking that down to a MAF issue. The ecm was supposed to be programmed to use an ls7 maf sensor since that is what my intake tube is adapted to use. At first it was showing no reading. I replaced it with a brand new ac Delco unit and got an IAT and maf reading. The odd thing is, the air flow parameter is showing approximately 18 grams/ sec and the maf parameter shows about 8-9. Not sure why there is the variance so I put on the MAF from the early 5.3 that goes inline with the intake tube. With that one, it starts and idles. The air flow and maf reading both match. I’m not sure if something was messed up on the tune or what. Also, I have verified the wiring to be correct for the ls7 card style and swapped it to be correct for the early 5.3 style. The second issue I notice is with my barometric pressure parameter. It is showing 22.4-22.6 Hg. My elevation is right at 3600 so I figured it should be closer to 26. I hooked up my scanner on my neighbors 5.3 swapped r10 and his baro shows 26.2 as does my brothers 2020 silverado. With me subtracting my map from my baro, it shows I am have about 13-14 inches of vacuum but my vacuum gauge shows 17 steady. Not real sure what the problem is with it and I have swapped map sensors to see what the issue is. Wasn’t sure if it could be related to the MAF issue or not but any help and advice would be appreciated!

I also forgot to mention. Sometime the ambient temperature shows the actual temp and other times it defaults to 32 degrees. Is this just a glitch or does it use the IAT to determine the ambient temp? I thought the only way it could be obtained was from an ambient air temp sensor in front of the radiator.

Thanks!