Jkchevy#1

I have a1990 silverado that I changed the 305 to a 4bolt main 350. The motor sounds good but it has some idle problems, when I crank it idles
good until i hit the gas then it dies. I have it timed and have changed the ecs, knock sensor, and injectors to a 350. I heard that I need a computer chip, is this true and what kind of chip do I need and why. please help!!!

vetteoz

iTrader: (13)

You need a factory memcal ( chip ) from same vehicle with a 350 engine
Your computer doesn't know you changed the engine and still thinks a 305 is in there

Jkchevy#1

Thanks alot! So where can I get this chip at does auto zone have one.

vetteoz

iTrader: (13)

Junkyard most likely

Jkchevy#1

Where do I plug in the chip

vetteoz

iTrader: (13)

You swap it with the 305 chip already in your ECM (computer)

RBob

iTrader: (1)

Which 350 engine was used? Such as L05 or one with Vortec heads, or? Cam?

Since you swapped to the 350 injectors it should at least run with the 305 PROM in place. Being SD it uses the ratio of injector size to displacement. Which is close enough to allow the engine to run well enough to be driven.

RBob.

Tuned Performance

iTrader: (92)

pm me I have alot of bin files and I can burn you a chip. You should have a 1227747 ecm that uses a 2732 eprom

UnderCover89TBI

iTrader: (25)

It'll run with a 305 computer, and prom. so that is not your issue. your issue is something not working the way it is supposed to. almost like a TPS problem or something.