Bought a 98 yukon with a great body but the rest needed work. So I put a performance 357 (upgraded cam, roller rockers, ported heads, headers, rebuilt trans, dual exhaust) just took it out today and noticed at 65mph I'm sitting at 1100 rpm. 33's and dont know the gear ratio. The gas pedal is not very responsive. If I want to pass someone I have to Floor it so it shifts down, goes to 2200 rpm and I can pass someone then shifts up and back to 1100 with no power, just cruising. but holy hell. Thinking maybe I need to flash the computer, change shift points, get a tune??? Any help?
New engine new trans no power :(
- Thread starter Mikeyslc
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big95hoe
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Definitely would get a tune and see what that does.
iamdub
Full Access Member
If you're running an engine modified to move more air (ported heads, cam, etc.) on a stock tune, that's gonna cause problems. What does the "357" mean, that it's bored to 357 cubic inches or that particular package is supposed to make 357HP? SES light is on, I presume?
Something doesn't right with your rpm's. I have a 98 tahoe with 3.73 rear end and 285 tires. At 65 mph, I'm around 1800 rpm. My 2004 silverado has the 3.42 rear end with stock tires, 235's, I think. At 65 mph, rpms are a little less, maybe 1600 to 1700. No where near, 1100. That sounds way too low. What rear end gear ratio, do you have?
