nonchalant
Not uncommon but good? no. The RFI deal, when you key the mic, is common. People have overcome it (sometimes) with some fiddling, re-routing wires, separating wires and twisting of pairs (from transducer). The gauge it self might be picking up the radio signals as well. Try moving and twisting the transducer wires.
If you search these forums or others you will see dozens of post about this. I recall Van said something like the needle being pegged did not hurt it and is nonchalant about it, ie ignore it. I think the amp meter also has this tendency, to peg the needle when transmitting.
As far as accuracy the baro is corrected for temp and humidity so the MAP will be off slightly, but a full inch is a bit much.
Going to zero with idle throttle? That is not great either, sorry don't know what to tell you, but I am not surprised. I also recall from my reading the transducers and even the gauge displays often have a short life and get replaced. One guy went thru a few transducers.
Not bashing Van or his gauges but its just not uncommon with this product. To be fair there are lots of these MAP gauges out there and many don't seem to have issues or they are not complaining. Consider sending both the gauge and transducer back to to Van's to be checked. To Van's credit they are pretty good about taking care of problems like this. It's possible you just got a bad one (trans or gauge). The RFI deal however is acceptable to Van I recall.
