I do agree that in the 99.99% of cases, it certainly is wiring/noise. Crappy power supplies and poor groundings are accidents waiting to happen.antus wrote:I know you have looked closely at the data in development of the obd xpro, but Im skeptical of this as the DLC is in hardware. I think the P04 DLC might have less buffer, though, and the later ones have fixed this. P04s are a bit crap in every way, to me they have the feel of being a beta quality design compared to the later ones. Lots of rough edges. For a P01/P59 Ive never seen this due to the operating system. Its always the interface, wiring or power (or a faulty pcm, though Ive never seen that 1st hand as they are pretty reliable)
But after dealing with the P04, I have noticed specific operating systems are not as tolerant, or send frames at crappy timings. In fact, my specific P04 is so unbelievably crap, that we have to add a resistor to the VPW line to help suppress noise. This was reproduced by Pete writing my ecus OS to his P04 and the exact same issues occurring. So far other ECUs have not been that bad, but it just opens the world of possibilities that timings are affected by the OS which is why having the ability to read/write at 1x has become important, since their may be other ecus with the same problem. I could only think that there are specific interrupt routines that are firing off (even when running a kernel) which are causing the undesired delays when writing data from ecu to the scantool.