Many times we hear from tool manufacturers how our old tools just don’t cut the mustard anymore. Your scanner for instance, is just too slow they tell us. How can you possibly diagnose anything with so much time in between frames?
So we all went out and bought DSOs. And now they tell us they are too slow. We need the new improved version to catch those super ultra fast glitches. You know, the ones that are so fast even the PCM doesn’t see them. The reality is though, that most of the time even scan data (as slow as it is) is sufficient when viewed properly.
The other day I received a 2000 Metro from our PDI man. Apparently it was cutting out very badly on acceleration. Scan data for Metros is very slow compared to GM vehicles, but what the heck… lets give it a try.
With Tech2 in hand, I drove about 100 yards before I got the snapshot I needed. Now lets look at it.
The IAT (intake air temp) and the ECT (engine coolant temp) sensors are both two-wire sensors. Following the age-old tradition, they are both thermisters with a negative temperature coefficient. A thermisters is a resistor that changes its resistance with changes in temperature. A negative temperature coefficient means that resistance will go up when the temperature goes down. Conversely, the resistance will go down when the temperature goes up.
It’s a pity that this scan data frame rate is too slow to fix anything…. <g>.
This is a new car, what would you be looking for first?