I just bought a 1992 stealth with a 3.0 dohc NON turbo stealth.The tac dosen't move at all.I traced the wiring from the ptu to the tac and its fine.This car when its cold it starts fine but sometime dies like someone shut the key off it seems when it warms up it dosent do that.Have you ever seen a ptu that will run the car but not send the tac signal or is there a more common problem?

 

I don't know of "a more common problem". Something is amiss, but I don't know what..??? I have checked the manual and could not find anything. Do you have access to a handheld (mechanic) tach. There is a place to hook it up (near the wiper motor). That would at least narrow down where the problem may be ie. not getting the signal from the PTU or the tach itself is malfunctioning. I will check the manual more when I have some time to kill. Good luck. Not so sure about your problem with it dying when cold, maybe your IAC (idle air controller) is dirty or malfunctioning. What does the car idle at when warm?? Let me know.

 

Just so happens I was browsing 3si.org and stumbled across this thread. It is not exactly like your problem, but it will show you where some diagnostic points on the ECU. Here is the link. Clicky

 

Well after checking it out i traced the hole ptu tac wiring and it turned out to be a bad ptu.It ran the car but was not giving a tac signal output.That problem is fixed. Now i have to figure out the other problem with it dieing after cold startup.I have noticed when it dies there is no spark or inj pulse.I am not sure if its in the cas or the mas sensor.

 

The CAS and the MAS are good places to start.. Look into the IAC (in the intake tract). It is a little solenoid like thing that adjust air flow. It could be dirty and/or broke. It is a lead anyway.

Good luck