ok guys this is the best area i can see for this question/s for a cadillac 4.6l with 308,000 mile if that is the original cluster and engine

my neighbor has this car and it has only the p0300 code. so his boy put in a new TB maf and map and it still has the code. so i put in new plugs but the old plugs looked good they had a .050 or more gap , i put the gap at .040 for starters. i did fuel pressure 50# vacuum is 18" taken from the booster port hose, i found some broken and worn wires located at the and under the TB rubbing on the antilock brake unit so i repaired those. i have not yet done a compression test as i do not have a tool to reach down that far into he heads, but i think i figured a way to do this today. he told me his boy put in a new TB and maf and map but i can't confirm if they are correct.

anyway i had him put some seafoam in the tank but he has not driving it much to get that working into the injectors. but when i did the live data some cylinders had tons of misfires when i ran the foxwell scanner on it i got tons of codes that will not clear so i think they a re history codes. but i got these for misfires
cylinders 1-49 2-2042 3-73 4-933 5-202 6-? 7-172 8-30 those were just for that scan. in live data. i have tons of data on drop box if anyone wants to see those and take a shot at what i see.

so outside of bad compression if anyone gets a chance to check out drop box data and tell me if may have a bad ecu? or some more wiring issues. that i'm not going to trace down it was hard enough to find the ones i did find

drop box links. these are photos i took with my phone page for page as the scanner will not let me load useable data with the sd card in the pc sorry way to get data i know but it is how i had to do it.

thanks for anyone wanting to try out ther online troubleshooting

https://www.dropbox.com/scl/fo/6msyq...wmek5mrlv&dl=0
https://www.dropbox.com/scl/fo/im29p...golnro0n4&dl=0

 

ok i did more testing and i have 180 to 200# compression all cylinders 18" vacuum 64# fuel pressure. ne plugs no codes for anything but the p0300 i found a few wire shorts so now with the basics out of the way my guess is either a computer or more wire issues. i'm not takin the harness out to check for shorted wires. he can get his boy to tackle that.

he had a TB MAP MAF installed and plugs now. i tested the booster to make sure that was not the vacuum issue and it held 10" of vacuum for 10 minutes that is plenty of time for the booster to show being bad

here is a drop box for the last scans live data and freeze frame.
https://www.dropbox.com/scl/fo/im29p...golnro0n4&dl=0