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With no codes; Intermittent No-Spark: Spark w/SPOUT Connector Un-Plugged, but Falter and/or No-Spark w/SPOUT Connected (similar to Hesitation, Stumble, Stall, Miss, No Start, No Spark); "It seems that the insulation around many PIP sensors breaks down prematurely - a condition that leads to shorting of the wires leading to the TFI ignition module. I always replace a PIP sensor along with a defective ignition module, if it has "soft" insulation...This month's column is about a Ford Ranger one of my students (Drew) said "would only run for about a mile, then die." Since we were in the middle of our electrical and engine performance unit, this vehicle would serve as a perfect troubleshooting opportunity. The story from my student went as follows: The vehicle began stalling intermittently during driving, but would usually restart right away. Sometimes, however, it would have to sit for a few minutes. Drew had replaced the ignition coil on the advice of a family friend, but the problem persisted. Next, the thick film ignition (TFI) module was replaced with a quality no-name brand from a local parts house. The stalling condition continued. Now, Drew had spent enough time with his friend to decide that the next logical course of action was to replace the entire distributor. This is where I became involved. As soon as I heard three ignition components had been replaced with no cure, I just had to mutter, "Sure, bring it in tomorrow!" The next day, I took the time to discuss with my students the proper method by which to approach this customer concern. Logical Troubleshooting Figure 1 - This is the old profile ignition pickup (PIP) sensor with defective insulation. Figure 2 - Believe it or not...Here's the original distributor with silicone around the cap sealing surface. Figure 3 - Here's the old distributor next to the new one, with the transferred ignition module. Figure 4 - New ignition coil. Figure 5 - Both the old and new spark plugs. Figure 6 - The root cause of the problem, which is the shielding wire grounding out the SPOUT signal. Troubleshooting is the process of testing a system to determine and isolate a malfunction. An automotive technician is often involved in troubleshooting a malfunctioning system on a car, such as this Ford TFI-IV ignition system. Skilled automotive techs do more than just troubleshoot - they logically troubleshoot. I tell my students they must approach this diagnosis just as a master technician would, by following a known, good, logical procedure that will isolate the root cause of the customer concern in a timely manner. The sequence I teach is: Verify the customer concern. Perform a thorough visual inspection. Test for the cause of the concern and perform published system testing. Isolate the root cause and perform the repair. Verify the repair. This is based on General Motor's Strategy-Based Diagnostics and I stress this to my students repeatedly. TSBs Drew found three technical service bulletins (TSBs) pertaining to the ignition system: TFI STALL NO START - TFI MODULE DIAGNOSIS AND SEALING: This bulletin addresses loss of module ground due to salt and moisture entering a module mounting screw. TFI ENGINE NO START/STALL AT IDLE - NEW IGNITION MODULE: This TSB talks about an internal short-circuit in some model TFI modules. DRIVEABILITY CONCERNS - MOIST EEC-IV CONNECTORS: This bulletin asks the tech to check for unsealed EEC-IV connectors and check for moisture or corrosion. Verifying the Concern, Performing the Visual Popping the hood on the Ranger revealed the new coil, new distributor cap and new TFI module screwed to the side of the distributor housing. The engine would only run for a few minutes before dying, just as though the key had been turned off. Sure enough, no spark occurred at spark testers when the no-start was present. Based on the TSB information, I directed Drew to inspect all of the EEC connectors and perform a complete inspection of all pertinent wires and components. We did notice that many of the wiring harnesses had some oil and road grime, and that there was some peeling of the wiring insulation at the EEC-IV module connector, although none of the wires appeared to be shorting. Now, Drew had already purchased a rebuilt distributor and plopped it down on our workbench. At this point I told Drew about a preliminary test that I learned to determine if the profile ignition pickup (PIP) sensor might be defective. We popped the cap and I pushed my fingernail down into the soft, gooey insulation surrounding the PIP sensor. This has historically been a red flag for techs hunting an ignition fault on Ford vehicles equipped with TFI ignition systems. It seems that the insulation around many PIP sensors breaks down prematurely - a condition that leads to shorting of the wires leading to the TFI ignition module. I always replace a PIP sensor along with a defective ignition module, if it has "soft" insulation. I liken this to replacing a high energy ignition (HEI) module in an older Delco-Remy distributor. Is it prudent to replace the ignition pickup coil while you're inside this distributor? I always let the customer make the decision, but I lobby for replacement. Drew was adamant about replacing the distributor, so I helped him through the process of marking the rotor and the housing, then swapping the TFI module from the old distributor to the new one. With this distributor installed, the Ranger now had a new ignition coil, ignition module, cap, rotor and PIP sensor. You can guess what happens next; the stalling condition is still present! Testing for the Root Cause At this point I had Drew's full attention, so we systematically walked through a proper diagnosis. A TFI testing worksheet showed a simple and systematic process that eliminates suspect parts and circuits, one-by-one, until the cause for the concern is discovered. The only problem, I explained, was that the engine would usually start right back up, and that made many of the tests ineffective. Still, we verified proper voltages at the coil, resistance across the coil and ground for the distributor. PIP Signal I decided to hook my lab scope up to the PIP and spark output (SPOUT) wires to isolate exactly where I was losing my signal to trigger the coil. The PIP signal is generated in the PIP assembly and is an indication of crankshaft position and speed. The PIP signal is fed to both the TFI module and the PCM. Hooking up to this signal with my lab scope would verify the entire distributor assembly. When the engine died and spark disappeared, the square wave produced by the PIP remained intact. SPOUT Signal The PIP signal is one of the many inputs processed by the PCM. After receiving all of its sensor inputs, the PCM produces a new signal called the SPOUT. The spark output signal represents the engine operating condition "electronically" and is sent back to the TFI module for comparison with the PIP signal. The TFI module then uses both of these signals to fire the coil at the proper timing interval. While watching the SPOUT signal on my scope, the square wave became jagged and jumpy as the engine sputtered, and then became a flat line before the engine died. Now we had a suspect - the PCM. A Break I noticed that when I unplugged the SPOUT connector to check base timing, and let the engine run at base timing, it never died. Unfortunately, this pointed me back to the PCM as a possible cause of my fault. But, when I plugged the SPOUT connector back together, I could make the engine falter and die by gently twisting the harness. Yes! I was sure I had located the fault, and I was right. Look at the figure with the yellow spark output signal wire that is without a section of insulation. This section happens to run through a shield ground that provided a convenient ground source for the SPOUT signal. Just the right bump in the road or vibration from the engine would provide a path of lesser resistance for the SPOUT signal, killing the coil trigger..."; etc. (for a Ranger, but similar).
By Brian Manley @
http://web.archive.o.../techtotech.cfm
Figure is gone. So try Wiggling the harness.
Ford came out with a similar TSB (FINALLY), Hesitation, Stumble, Stall, Miss, No Start, No Spark and/or Diagnostic Trouble Code (DTC) 211 TSB 95-15-11 for 93-95 (Shorts in Profile Ignition Pickup (PIP) & Spark Output (SPOUT)); "..The symptoms may occur during any drive mode or at idle. These concerns may be caused by the shielding drain wire (Circuit 48.) cutting through the insulation of, and shorting to, the Profile Ignition Pickup (PIP) wire (Circuit 395) or the spark output (SPOUT) wire (Circuit 929) near the Powertrain Control Module (PCM) 60-pin connector. A protruding wire from Splice 145 may also cause the same concern as the wire strand shorts to the PIP, SPOUT, or the foil wrap surrounding the drain wire..." @
http://ww2.justanswe...tion_module.pdf
This is for fender MOUNTED TFI Module.
