My Ignition System Adventures
Problem: engine cranks, but will not start - no spark coming from coilwirePossible Causes: coil, TFI module, EEC, cap/rotor/wires, wiring
Background: the ignition system consists of the coil, cap/rotor, a Thick Film Integrated Module (pic), Profile Ignition Pickup/Hall Effect sensor (pic), the Electronic Engine Control, and the distributor. The TFI module sometimes takes a special thinwall 5mm/7/32 socket to get it off, and it's a bitch to get to, as is the distributor in general. The PIP sensor is more or less not replaceable since a special puller is required to get the distributor apart to get to it. I bought a remanufactured distributor (with PIP preinstalled) from Auto Zone.
Wanna hear a song about my Cadillac? More of my music is here.
Tools Needed:- HEI spark tester
- testlight
- multimeter
- Ford Ignition Module socket
- paper clips
- remote starter switch (not 100% necessary, but very helpful)
Tests:
- visual inspection of all components. look for frayed wires, loose connectors, anything worn or broken, cracks in dist. cap, rotor tip gone
- check inertia switch (passenger footwell, behind carpet) push button down to reset
- disconnect SPOUT (pic) and see if problem persists. if not, probably bad EEC. if so, more like TFI or PIP
- check spark from coil wire using a spark tester
- if no spark from coil check
- resistance of primary coil winding
- resistance of secondary coil winding
- resistance of path to ground - from + side of coil to ground should read infinity
- 12v voltage at positive terminal of coil
- other checks from Test Sheet
- before pulling cap and rotor, mark cap to base, distributor to block, rotor position and rotor to crankshaft marks to make sure everything goes back together right. I managed to put the distributor back in with the rotor 180 degrees out of phase, firing on TDC exhaust stroke, not realizing that the crank made 2 revolutions per cycle.
- To find true TDC, remove #1 plug and feel for compression while rotating engine. Crank balancer marks aren't enough.
- Paper clips are handy for inserting into the tiny holes most auto electrical connectors have. Then just alligator clip the test leads of the multimeter to the paper clips for easy testing.
- Unplug injector connection before cranking too much, or you'll flood the engine
- If your distributor's remotely old, and you have to pull it to get the module off, might as well replace the distributor with a rebuilt one, rather than having the PIP sensor go bad and kill the module and leave you stranded somewhere. Otherwise, when it does, you'll be buying a new distributor AND module.
This was a tough one to track down. It happened in the dead of winter for me, so I'm still mostly salty just because I had to work on the truck in 20-degree weather. Even still, I'd love to punch the engineer in the mouth that decided to shoehorn the distributor between the firewall and intake manifold. It's not as if changing cap/wires/rotor is a once-in-a-lifetime thing. This whole process was complicated times five just because the distributor is such a pain in the ass to get to. To make it worse, the TFI Module fails at about 260+ degrees. Considering that most engines run in the 200-degree range, that's not much margin for error, and I call that bad engineering. So do many others:
Send any questions or comments to jason@slipangle.org.