I have nobody but myself to blame, but it still feels awful. My first fail on a checkride ever. I'm a grown man and I almost feel like crying.. Funny thing, I thought the oral was going to be the part I'd fail on if I'd fail anything (as I can't remember sh*t these days), but in the end it was the flying that got me. No need to go blow by blow, but the root of all my troubles was the 430W in my plane. I didn't "come up" flying Garmins (or GPS at all), and didn't have one in my old plane, so my knowledge of it is skin deep. I must have fooled my instructor enough to think I was proficient in it, but in the end that was the beginning of the unraveling. If it's in the plane, database current, then it's fair game for the DPE and he did what he should have done. I know this DPE very well as he's trained me before and I've taken rides with him in the past. He's tough on you, but fair. I couldn't fault him at all for failing me - I would have done the same. Awful flying and knowledge about systems on my behalf. In summary, I was late switching over to VLOC for a VOR circling approach, fast and high and had to scramble to get it in. On top of that I had always done that circling approach by crossing the rwy, but now he got mad at me for not joining the downwind on the closer end. It threw me and from there on it was all downhill. I was also supposed to go visual at VDP, but was fuzzy on how a VDP was defined. Not something I'd really spent any time on. I departed airport using the DP in use as per clearance, but then they started vectoring me and finally said "Join V389". That was the final trap - I didn't know how to enter a V airway into the 430 (and it turns out you can't) but I should have put in one of the wpts that was on that V airway to intercept. He even hinted and tried to help, but my lack of 430 knowledge and understanding was just not there. After that partial panel stickers came up. I started navigating by the GPS, but he had the page up with the CDI on the screen, and I'd not had enough experience on that one. If I'd recovered from here and improved, I think I would have passed. But I didn't. By this time I was well behind and he now failed my right engine on me. I was disoriented by now and turning to the wrong heading on the 430 CDI, forgetting ATC's vector etc. "My controls" and that was it. Finished off the remaining items - RNAV approach, but again had trouble with the hold as it was a wpt in the middle of nowhere on the 430. I'd never done anything but the published or missed holds on it before. Funnily enough, I know that had I just gone old school, done VOR's, LOC's and ILS's, pen and timer, I would have done much better. The GPS - that's supposed to help with situational awareness - was what got me. Again, my own fault. Hey, live and learn. I'm clutching a huge drink as I write this. It feels good to get to write about it, like a catharsis. I'll need to do two approaches and hold on the next ride. Hopefully I won't screw it up a second time. I need to learn the 430 front and backwards and be ahead of it, not behind. Thanks for you time.