Trying to understand
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Joined: Jun 2022
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Trying to understand I started working at a shop were most cars that come in are older and have chevy engine swaps I'm talking about like impalas, contennitals, cars before my time with chevy 5.3 engines I'm a modern car worker I work and understand everything electrical on new vehicles but what gets me wondering is how do some of these cars come in with a factory chevy pcm with an aftermarket harness on them I have seen some videos on YouTube were they can take out certain pins that they will not use but doesn't that mean that the pcm can still detect them or it just that the system is to old on the chosen pcm for example lots of the swaps I see don't have the rear o2s or the evap purge valve or do they just flash the pcm so it does not see those sensors
TECH Senior Member
Joined: Jun 2016
Posts: 22,291
Likes: 3,616
From: Central Cal.
I started working at a shop were most cars that come in are older and have chevy engine swaps. I'm talking about like impalas, contennitals, cars before my time with chevy 5.3 engines.
I'm a modern car worker I work and understand everything electrical on new vehicles but what gets me wondering is how do some of these cars come in with a factory chevy pcm with an after market harness on them?
I have seen some videos on YouTube were they can take out certain pins that they will not use, but doesn't that mean that the pcm can still detect them or it just that the system is to old on the chosen pcm? For example lots of the swaps I see don't have the rear o2s or the evap purge valve, or do they just flash the pcm so it does not see those sensors?
I'm a modern car worker I work and understand everything electrical on new vehicles but what gets me wondering is how do some of these cars come in with a factory chevy pcm with an after market harness on them?
I have seen some videos on YouTube were they can take out certain pins that they will not use, but doesn't that mean that the pcm can still detect them or it just that the system is to old on the chosen pcm? For example lots of the swaps I see don't have the rear o2s or the evap purge valve, or do they just flash the pcm so it does not see those sensors?
Fixed it....
Some computer settings can be deleted with a laptop. A common one is misfire codes due to a cam change. Fuel trims are changed as well. You need to research the tuning forum here to understand it better.
