Progress Thread 99 Mustang

99MustangQuinn · Feb 12, 2020

I have a 99 Mustang with a 04 transmission.. It will only go 29mph before it governs it self out my dash reads 120mph.. I changed the speed sensor but still only will go 29mph.. Would it work if I deleted the speed sensor an I used my GPS as my speedometer? Or is there something else that would work that I can do?

wmburns · Feb 15, 2020

The reason WHY your speedometer is not correct is because Ford changed the number of teeth on the OSS reluctor wheel between the 1999 and 2004 model year. This problem can be fixed by re-programming in the same way as what is required when changing a rear end gear ratio.

The other way to fix this is with a tail shaft swap. Here's some more information that may help.

T-45 Tail Shaft Swap

T-45 Tail Shaft Swap

Please feel free to hit me up with any corrections I have overlooked... This write up is for the T-45 tail shaft swap. I had to change my tail shaft due to the magnetic speed sensor (found in the 99+ models) as appose to the gear driven sensor (96-98 models). Car getting the tail shaft swap...

www.allfordmustangs.com

IMO the best option is to re-program the PCM to correctly understand the different number of OSS speed sensor teeth.

Progress Thread 99 Mustang

99MustangQuinn

New Member

wmburns

T-45 Tail Shaft Swap

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Progress Thread 99 Mustang

99MustangQuinn

New Member

wmburns

T-45 Tail Shaft Swap

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