2011 Ford Ranger 4.0L no spark

Discussion in 'Engine Tech' started by jsmith51, Sep 21, 2021.

  1. jsmith51

    jsmith51 New Member

    Hello, I'm new here, sorry if someone has already found a similar problem as to what I'm fighting with on this truck. I've read through hours of posts, but haven't found any progress in my testing.
    I have a 2011 Ford Ranger 4.0L, 5 speed manual, 4x4 truck, under 94,000 miles. The truck had a timing chain guide failure and sat for about 1 year. I recently pulled the engine, put new head gaskets, replaced all the timing components, also used a timing tool set for reassembly.
    The engine cranks but will not start. I have a Matco scanner, no codes available. I see engine RPM, tested injector pulse with a noid light (injectors are firing, so I'm pretty sure the crank sensor is okay but tried 2 different new ones), I did a compression test on each bank at 175 PSI in two cylinders I tested, also pulled the driver side valve cover and rechecked the cam timing with the tool.
    I have 12 volts to the coil block, but I'm not seeing the ground signals from the PCM to the coil block in order to charge and trigger the coils to send spark to the plugs. I haven't been able to find a pin out for the PCM connectors but I did open and inspect the harness for any loose connections or broken grounds..
    Anyone have any ideas as to what I am missing? I guess its possible the PCM has failed after sitting but I would like to be sure before replacing it.
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  3. Doug

    Doug New Member

    Just wondering if you ever figured out what was causing your no spark/no start issue, because I have an automatic 2011 Ford Ranger with the same conditions after replacing timing chains (cranks but won't start with the PCM not sending ground signals so no spark, but it does have injector pulse). We have replaced the PCM and it hasn't made any difference. We also have good compression and 12 volts to the coil, with good signal from the crank sensor.
  4. Doug

    Doug New Member

    Our Ranger is alive. Looking at the signal from the crank sensor with a PICO scope, once we blew it up enough to really study it, we saw some noise in the waveform where it has the missing tooth. It was just enough to cause the ECM not to recognize TDC so it never fired spark. The older 4.0 SOHC harmonic balancers had the tone wheel cast as part of the hub. The newer ones have a squirrel cage style wheel pressed on the hub. The missing tooth still has a nub on the front part of ring. We thought that maybe the crank sensor was picking up a signal from that nub so we pulled the balancer just until it started to move. That cleaned up the signal and the truck fired right up.

    What caused all of this? We used a Cloyes timing set so I got another set with the same part number. When I measure the thickness of the OE crank sprocket compared to the aftermarket one, the OE is .005" thicker. So our balancer and tone wheel moved .005" closer to the engine block. You couldn't see that with your naked eye and you wouldn't think that it would cause a problem, but it did. We ground .050" off of the nub where the missing tooth is and it is good to go.

    The strategy for this engine is to fire the injectors as soon as it sees crank signal and fire spark as soon as it recognizes TDC from the open window on the crank tone wheel. It doesn't care which cylinder is on compression and which is on exhaust because it is firing both cylinders anyway. Cam timing has nothing to do with it until after it runs, then it syncs injector pulse to the intake valve timing.

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