Pcm compatibility

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Joe Dirte

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So my 98 Silveraydo was originally a 305. Swapped in a 350. Didn't swap pcms. Can the 305 pcm run the 350 with no issues? This never popped into my head until yesterday.
 

tpass

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Is it running now? did you swap the intake/fuel system over from the 305?
 

Joe Dirte

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Is it running now? did you swap the intake/fuel system over from the 305?
It runs but runs rough. Used all the 350 stuff. Motor ran like a dream when I bought it. 2nd motor that's developed a #5 misfire out of no where.
 

Joe Dirte

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You could use that PCM, but it nees to be programmed with parameters for the 350.
Picked up a 350 pcm today so maybe swap em if rain let's up see if it idles smoother but it'll need programmed too.
 

torhne

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Mite have to look into it. Hopin it's nothing internal with motor. Shouldn't be with 2 motors doin same thing. Maybe somethin in pcm lost connection. Who knows.
At that point, I would do the 0411 swap. Its easy, takes a few hours. And then you can really tune it.
 
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