2006 mustang gt dei alarm tach connection

I have a manual 2006 mustang GT. I've tried to learn the tach because I must use the viper 5704 in Manual Transmission Mode. Therefore, I have to use engine sensing on tach mode. However, the car shuts down after remote starting within a couple seconds. I know this is not the immobilizer because the car will remote start fine on auto trans mode under voltage or virtual tach sensing. I am currently using the negative wire of coil of piston #8. Anyone know where or how I can fix this problem?

Did you go through this list?

MTS - Manual Transmission Start diagnostics
When enabling MTS, if you get a failure notification from the remote or the vehicle fails to remain started
check for following:
• Tachometer not connected or programmed.
• E-brake not connected to the remote start unit. The BLACK/ white H2/2 neutral safety wire must have
a ground when the parking brake is set.
• Foot must be off the brake when activating the MTS mode on the remote.
• Is the door open when enabling the MTS mode? If so this would cause the unit to enter Pit Stop Mode
and the remote start will continue to run when arming/locking the system.
• Is the door input connected? The system needs to see a door open then close after initiating the remote
start.
• Does the vehicle have a delayed dome light? If you are connected to the dome light wire and the
dome light is staying on after arming/locking the system, the system can exit the MTS mode.
• Make sure the neutral safety switch is plugged in and turned on.
MTS mode exiting diagnostics:
If the remote start has entered the MTS mode but exits the mode after the system is armed/locked. Check
these for possible causes.
• The vehicle door has been opened or the security system has been triggered in your absence.
• Does the vehicle have a delayed dome light circuit or does the dome light come on when the ignition
is shut off? If so you may need to go to the independent door inputs of the vehicle.
• If you are connected to the dome light wire in the vehicle and cannot connect the system to the
individual door inputs of the vehicle due to it having normally closed door inputs, you can use the
Xpresskit DTIMAZDA module or Tech Tip # 1921 at www.directechs.com to interface with these
types of circuits.
• The E-brake wire connected to the neutral safety input of the system loses ground when ignition
is turned off or after a certain amount of time, with these vehicles unfortunately there is no workaround.
• The E-brake wire connected to the neutral safety input of the system has a poor ground. Clean the
contacts on the switch or replace the switch

I double checked all my connections as was able to go through the mts shutdown steps. When I perform te steps, the remote sart says on, control center and parking lights flash 5 times then before I even get out and shut the door and arm, the vehicle shuts down, and remote start turns off on the remote. If I try to remote start the vehicle, the parking lights flash 7 times indicating that ms mode was not activated. I think that it must be the tach because it wong stay started on tach mode even in auto transmission mode. In that mode the vehicle will start then shut down after a few seconds. It only does this when engine sensing is on tach mode. I learned the tach but I think that maybe I am not getting a proper tach signal. It works if engine sensing is in virtual tach or voltage mode, but because I need mts mode to work, tach mode is required. Any ideas on where I can get a proper tach signal? Right now I am connected to negative coil wire on piston #8.

Try going to a F.I.   Bulldog and DEI say any wire not Red and Audiovox has this info :
 4.6 LITER  Tach    TAN/BLACK (A/C)    AT FUEL INJECTOR

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Soldering is fun!

@ kreg357 I'll try that out and update you guys if it works. Thanks for the input guys, much appreciated