Have Ford Questions? Ask a Mechanic for Answers ASAP
Are you getting spark to the plugs? Is it a blue spark? or is it weak? Have you tried putting old plugs back in? Have you checked pick up coil & connections? See http://www.autozone.com/ignition-tune-up-and-routine-maintenance/pick-up-coil/duralast-pick-up-coil/ford/e350-1-ton-van/1989/8-cylinders-g-7-5l-fi/884_0_0/
Check to make sure there is no bare wires grounding out and no burn marks on pick up coil. If you are getting a good blue spark to all plugs, the problem lies with the plugs. Use Autolite or Motorcraft plugs.
Is your TFI module gray or black? It should be gray. Ignition dwell with the Push Start (gray module) system is controlled by the TFI module alone, and increases with engine rpm. The Ignition Diagnostic Monitor (IDM) signal on a Push Start TFI system comes from the coil negative circuit and is filtered through a 22k ohm resistor to pin #4 on the EEC-IV computer. The computer monitors this circuit to verify a coil firing for each PIP signal, and sets codes if it sees missing or erratic signals. Another feature that is unique to the Push Start TFI system is the start input on pin #4 of the module connector. This is wired into the starter relay trigger circuit, and signals the TFI module that the engine is cranking. When the module sees battery voltage on this circuit, the SPOUT signal is ignored.
See this link: http://www.megamanual.com/ms2/TFI.htm This is a diagram of what each wire does that goes to the TFI.
Make sure you have the correct TFI module. See: http://www.autozone.com/ignition-tune-up-and-routine-maintenance/ignition-control-module/duralast-ignition-control-module/ford/e350-1-ton-van/1989/8-cylinders-g-7-5l-fi/208884_90764_0/
Distributor Mount versus Remote Mount TFI-IV ICM
TFI-IV ignition systems have two distinct configurations. In the first configuration, the TFI-IV ICM is mounted on the distributor and has three pins, which plug into the Hall effect camshaft position sensor (commonly known as the PIP or Profile Ignition Pickup sensor) inside the distributor. This configuration is called a distributor mounted ICM. In the second configuration, the ICM is not mounted on the distributor but in another location within the engine compartment. This configuration is called a remote mount ICM.
The distributor mounted TFI-IV ICM uses a Universal Distributor that has an opening in it through which the pins of the ICM plug into the CMP (PIP) sensor. The remote mount TFI-IV ICM uses a Sealed Distributor. The CMP (hall effect PIP) sensor is located inside the distributor on both configurations. There are no mechanisms on either distributor for either centrifugal or vacuum advance. The CMP sensor inside the distributor responds to a rotating metallic shutter on the distributor and produces a digital PIP signal. The PIP signal is an indication of engine rpm and engine/piston position for both the ICM and the PCM. Because the shutter is mounted on the distributor shaft, two revolutions on the crankshaft are required to fire each sparkplug once. The distributor rotates at half the crankshaft speed.
Make sure you have the correct TFI module. There is a difference and your module is vehicle specific.
For testing TFI module see http://easyautodiagnostics.com/ford/4.9L-5.0L-5.8L/ignition-control-module-tests-1
See also http://www.myo-p.com/Ford-EEC/EEC%20Help%20files/Files/TFI%20test%20and%20troubleshooting.html