Hi Bill,Originally Posted by BillBoost37
I hope you've been doing well other than your car. Figure I could add a few thoughts. When you say hiccup, could you describe the symtom a little more? As you may know, sensors can sometimes get skewed and the PCM wouldn't detect a problem (set a code) unless they really got way off. For sensors that failed internally through an open or short will usually bring on the CEL. Even a broken or shorted wire would bring on the CEL. That's why I mentioned about a sensor being skewed and not possibly setting off the light.
For all of the sensors that you mentioned for cases where the PCM may not detect a problem, I connect a 4 channel Picoscope to it and confirms them one way or the other. Scan tools or not the best for looking at raw data from a sensor since the values are read from the PCM. And the scan tool is usually too slow to pick up intermittent problems from a sensor. The scan tool could read values between a fault condition.
If you don't have a scope, the next best thing is to use a voltmeter with a min/max feature which could capture dropouts such as from the TPS. The MAP sensor could also be checked this way. The MAF sensor puts out a variable frequency relating to the amount of air being pulled in. Most meters today, at least the midrange ones have a feature which allows you to measure frequency or at least the duty cycle of the waveform. But again, the best method to confirm all of these sensors is with a scope. I hope this gives you a few ideas to help in checking out your vehicle.
After a little thought, your hiccup sounds like it may be an ignition misfire. Does you scanner have a feature to look at the misfire counters? Maybe a bad plug wire.
Terry
