Shifting issues - The 1947 - Present Chevrolet & GMC Truck Message Board Network

tbrown5079 · 06-26-2016, 09:09 PM

Did a 4.8 from a 06 GMC Sierra pickup into a 56 Chevy truck. All components from that vehicle. Motor runs strong, no check engine light, but when shifting into 3rd it seems like the transmission is confused. It will seem like it is in neutral then when you give it more gas then it downshifts. If you pick up more speed then let off the throttle, it will slowly shift into third. Took the pan down and both solenoids are firing. Today I calibrated the electronic speedometer but that didn't help much. At least I know I am getting a speed signal from the ECM. Is my next step to check the shift points in the tune?

06-26-2016, 09:09 PM	#1
tbrown5079 Registered User Join Date: Feb 2007 Location: Blairsville, PA Posts: 301	Shifting issues Did a 4.8 from a 06 GMC Sierra pickup into a 56 Chevy truck. All components from that vehicle. Motor runs strong, no check engine light, but when shifting into 3rd it seems like the transmission is confused. It will seem like it is in neutral then when you give it more gas then it downshifts. If you pick up more speed then let off the throttle, it will slowly shift into third. Took the pan down and both solenoids are firing. Today I calibrated the electronic speedometer but that didn't help much. At least I know I am getting a speed signal from the ECM. Is my next step to check the shift points in the tune? __________________ tbrown's 56 Cameo Build



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.