So here's my issue. I've been running my car without the tach since I got it back together in 2005. I've had the rev limiter set and it rarely reaches anything near the limiter, so it's really no big deal. But anyway, I had a hair to finally get my tach back last week, so I tore into everything to try it. The tach adapter is wired correctly to the Digital 6AL and power circuits. I wired the tach output directly to the tach "C" input on the backside of the tach and it has the V8 adapter on the back it. I've chased my tail with some of this, checking connections, grounds etc, but can't seem to really come up with a definitive cause except that possibly either the 8920 is bad or that maybe I no longer need the V8 adapter, and I'm leaning toward a bad 8920. I'm also questioning if my tach can take the 4/8 cylinder signal or if it's possibly a V6 gauge. But here's what it's doing: the tach kinda jumps around at first, then settles and looks like it's reading normally. Then, a quick blip of the throttle and it pegs the 6k mark, then sporadic and back to "normal" reading at idle again. I have a quick video on my phone that I'll try to upload to illustrate. But anyway, does anyone have a good test procedure for either the 8920 or the stock tach to possibly verify what is actually going on? I believe I found a quick test for the 8920, but haven't been out to check it yet, so if anyone knows a good test procedure I can at least verify what I've found so far. Thanks!!
