Auto Service Professional

FEB 2018

Magazine for the auto service professional

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17 | ASP February 2018 Circle 106 on Reader Service Card RETAINING RING PLIERS NEW Part# 3595 • Convertible for use on internal/ external snap rings • Cushioned grip handles • Ergonomically designed switch allows user to change between internal and external with ease without separating the pliers • Packaged in a plastic blow molded case for protection and easy use 85 YEARS OF QUALITY TOOLS! Also available in a six piece kit or individually. Technical will force the engine back into open loop and cut off the injector from the misfiring cylinder, which means the fuel trim values cannot be used as we explained earlier. It would be necessary to view the scan tool fuel trim parameters before the PCM forces the engine back into open loop. A recent case study involved a 2001 Honda Odyssey that came into my shop with a misfire symptom and no MIL with no codes, not even a pending code. Since this was a non-CAN-compliant system there were no misfire test results in the Mode 6 menu. You can't say enough about the good old "feel through the seat of your pants," the engine was running on five cylinders! e front coils were easy to get to so we manually disconnected one at a time and monitored the rpm drop. While disconnect- ing the number 4 coil we never got the rpm drop. Putting a spark tester on the number 4 coil showed no spark. Could it be a common COP failure? What about the ignitor drive signal from the PCM (see Figure 7)? You will see a 5 volt/0 volt toggle, meaning that the PCM is sending the control signal and just like the GM systems the ignitor is forward biased by the PCM. Now let's say the ignitor signal was flat lined at 0 volts. Could the ignitor have shorted the PCM driver? We could easily find out by unplugging the coil. e 5V ignitor control voltage is sourced at the PCM. If we get our 5 volts back then we know the ignitor has shorted the PCM control voltage. However, in this case the ignitor control signal was present and the problem was simply a bad coil. Once the coil was replaced we should still analyze the waveform (see Figure 8). Is there a noticeable lower coil saturation value on the number 4 coil? If your answer is yes, you are correct. If the primary feed voltage is good to this coil, then the coil should be returned to the parts sup- plier because the coil's amperage saturation values are significantly lower. On the Toyota COP systems the ignitors are also integrated into the coils the same as the GM and Honda systems, so access to a

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