Xm Radio Drift in Acura NSX

I have a bizzare problem here.  I have installed two separate units an Alpine  CD head unit and a pioneer avic-N2 in my NSX and the XM radio drifts in and out while moving.  Before I get the obvious question, These units were not installed simultaneously. (Grin)  I lose signal for about 2 seconds every 30 seconds and the problem does not seem to be directional.  I've tried three different antennas the latter being a two wire pioneer and the result is the same.  I've moved the antenna from the rear deck to the center of the top and onto the dash.  No Change.  The XM module was first installed in the rear trunk and is now located in the front sharing the same power and ground source as the head unit.  Each unit works fine in my Isuzu Rodeo with no drift at all.  As soon as I install into the NSX the XM drift returns. 

Oh, last little tidbit.  I have an XM roadie II that works perfectly when plugged into the cigarette lighter and the antenna is just thrown onto the dash.  Go Figure.  I'm clueless here.  My installers are ready to run and hide as soon as they see me coming.  Has anyone out there got a solution to this problem?  Thanks  Rich

have you tried the placing the antenna on the outside of the nsx?

Try grounding the module directly to the battery and also run the constant straight to the battery. The NXS' aluminum construction makes a grounding point really tough for aftermarket electronics. Grounding from the  battery is your best bet and see what happens.

Thanks Jeff85,  We have placed the antenna on the outside both in the center of the rear deck and in the center of the top.  There is no difference in any location.  We actually tried all three antennas in all locations.  Also the roadie II worked perfectly with the antenna just thrown on the dash.  I drove all the way from Tennesee where I purchased the car to San Diego Califonia where I live and not a single glitch.  Still scratching my head.  Grin.

Thanks also Velocity Motors, The main power is already coming directly from the battery.  BTW, even though the car only has around 30k miles which means that by Honda standards the electrical system is relatively new, I have changed to a high amp hour Gel Battery.  The ground however I'm not sure of the origin.  I'll look into that tomorrow.  On the topic of gounding, I've noticed on ebay when searching NSX that people are selling ground stabilizers.  It appears to be a device that installs on the neg side of the battery and per the description does all kinds of wonderful things like better performance, better ignition, does your dishes, ya de ya.  You know how ebay goes.  On the other hand is this something that I should consider?  It's around $45.00 US so cost is not a consideration if there is an actual benifit.  Just curious if you've had experience with these things. 

One more symptom that may or may not be related but I get a huge amount of ignition static on both AM and some FM channels.  The static is spark plug noise not alternator whine.  I've replaced the plugs with iridium plugs to the tune of $185.00 ouch and it's still a problem.  Replacing six coil packs is not going to happen.  After choking on the price of those puppies my ears developed unbelievable static filters.  LOL  Thanks again for all your help here.  I'll keep you all posted on the grounding results.

Maybe I should describe the rest of the system on the chance that something may be relevant.

94 Acura NSX, Pioneer Avic-N2 (Gripes about that one another day), Pioneer 12 disk CD Changer, Pioneer Ipod interface, 400Watt Nakamichi 4 channel amp, Boston Pro series 6" In doors, Boston tweeters up on dash.  JL Audio 8" sub in passenger foot rest.  System runs on it's own power bus directly from the Gel battery. (Ground plane is still a question).

C Ya