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It's been a long time since I last posted. I built a 32 Hudson Essex Terraplane street rod using the engine/transmission/ECM from a 96 firebird 3.8. The engine is stock, other than a turned throttle body, headers, and the elimination of the cat. It seems to run ok, but there is the constant shifting at normal driving between lockup, and sometimes OD. To expand more on the car drivetrain. I have a 8" ford differential with a 2.79 gear ratio. I'm also running some rather tall tires. The GPS speedometer tells me that the car is traveling 14 mph faster than the ECM thinks. Also the drag coefficient of the body is quite poor compared to the firebird. I've adjusted the brake switch to eliminate a false decouple, and the cruise works ok. I'm thinking the rpm vs throttle position vs manifold vacuum. is way out of the normal transmission operating range. I do plan to drop the gear ratio to be within 10% of percevied speed. Am I missing something ? I am running the engine/transmission with a nose down rake compaired to the stock firebird. I level the engine with a jack to set actual fluid levels, as the body rake decalibrates the dip stick. I've shifted to be out of OD, but the lockup still can't decide where to stay. Any thoughts? 20180530_163112.jpg
 

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If you can get the MPH reading closer with corrections to the appropriate tables, you can work on the speed/rpm settings that control the shifts/TCC settings.

What PCM are you using, and what are the various settings at right now? If you share more of the details, it'll be less hazy to make suggestions that can amount to guessing from just a story.
 

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It's been a long time since I last posted. I built a 32 Hudson Essex Terraplane street rod using the engine/transmission/ECM from a 96 firebird 3.8. The engine is stock, other than a turned throttle body, headers, and the elimination of the cat. It seems to run ok, but there is the constant shifting at normal driving between lockup, and sometimes OD. To expand more on the car drivetrain. I have a 8" ford differential with a 2.79 gear ratio. I'm also running some rather tall tires. The GPS speedometer tells me that the car is traveling 14 mph faster than the ECM thinks. Also the drag coefficient of the body is quite poor compared to the firebird. I've adjusted the brake switch to eliminate a false decouple, and the cruise works ok. I'm thinking the rpm vs throttle position vs manifold vacuum. is way out of the normal transmission operating range. I do plan to drop the gear ratio to be within 10% of percevied speed. Am I missing something ? I am running the engine/transmission with a nose down rake compaired to the stock firebird. I level the engine with a jack to set actual fluid levels, as the body rake decalibrates the dip stick. I've shifted to be out of OD, but the lockup still can't decide where to stay. Any thoughts? View attachment 11023
If I were in your shoes, I would contact DYNO TUNE MOTOR SPORTS and talk to BRIAN TURNER. He is very good at tuning pcm/ecm's which he can do. He would need differential gear ratio and tire circumference for the best results. I have had him do some reprogramming for me and it was 100% great. YOU SHOULD CONTACT HIM AT DYNO TUNE motor sports. I believe he's in OHIO and shipping/recieving via UPS will work.
 
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