I showed the mechanic during a test drive that the nav system consistently places the car 20-50 yards behind where it really is. This happens in all directions so the vehicle location fix won't address this.

I should ask them to test drive an 06 and see if it does the same. If not then it's worth trying the new software, for me anyway.

 

There is a way to adjust that in the technicians control via the interface.
You need to get to the diagnostic screen, and you can adjust the GPS position on the screen.

 

AFAIK that only works if the position is offset in one direction. I tried adjusting it and it didn't help at all. In other words, no matter what direction I approach an intersection from, it'll always show that I'm 20-50 yards back from where I really am. I think the communication between the GPS and nav system is too slow. The reason it doesn't catch up when I stop is that the dead-reckoning sensor (speed + direction) tells the nav that the car is no longer moving so it stops updating. That's a long shot though, I'll admit.

 

I have been having the same problem. It has caused me to miss a number of turns. Adjusting it doesn't help. I agree that it looks like the processing and/or receiving of information by the system is too slow.

 

Thanks for posting. It would be weird if I was the only one who had this but it's possible I suppose that it depends on the location or perhaps hardware.

 

Well damn, as part of the 'analysis' they reset the nav system which means it lost its address book. Who builds a system that can't be reset without zapping customer data? That's just stupid.

 

Nocturnal - I confirmed the same inaccuracy in my nav, but if its just slow processing, wouldn't the system catch up if you are going real slow? I tried inching my way to an intersection and it did not "catch up". Interestingly, the front edge of the circle around the car indicator seems to be right on when in the highest zoom level.

 

Getakey, yeah, that's a problem with the theory indeed. Perhaps the dead-reckoning navigation affects it at slow speeds. Something like the dead-reckoning providing a sanity check on the data from the GPS ala "no way can I be moving this fast because the speedometer says I'm only going X miles per hour". I'm grasping at straws here and could be completely off though. I'm interested in hearing all theories.

 

I am going to look at it again tonight, but it seems to me that it is the same distance off whether I am going 70mph or 30 mph. I use overpasses/intersections as a benchmark.
The bigger issue may be how fast it is decompressing and then displaying the map info from the DVD.
What's everyone's experience with other Nav systems?

 

If it is indeed sometimes 70 yards you seem to have a problem. For a while my BMW iDrive (crap Navi) system had always me going a different cardinal direction than I was indeed traveling but then corrected itself after a few days.

But the Acura Navi sure better than even 20 yards. Has the dealer run a check on the system? Perhaps bad GPS antenna or something (intermittent, low enough signal strength to only get reception part of the time ... just some thoughts).

BTW the history of GPS was that prior to 2000, what was called "Selective Availability" was turned on in the GPS constellation. It was so that only U.S. military receivers could truly know the exact accuracy of their positions. Civilians would be limited to no better than 100 meters (328 feet or about 100 yards) accuracy. With the lifting of SA came about 10x better accuracy -- about 20 meters (66 feet) in marginal conditions, to less than 10 meters (33 feet or 10 yards) in good conditions.

I'm assuming your problem is happening regardless of view to the sky. So, let's say it's happening in wide open sky. Just by GPS alone you should be seeing better than 10 yard accuracy. In my experience, it's more like 10 feet accuracy with dead reckoning.

By this analysis, it sounds like you have a problem that is deserving of an investigation by the dealer (er ... stealer).

 

I haven't had a problem with the timeliness of the nav directions in my 06 RL. No missed turns.

But I have found that when I try to add an address to my address book based on the current location, that the street number is wrong. I've always been stationary when attempting to do this.

Is this due to a GPS calibration issue, or are my expectations for GPS/Nav DVD data too high?

Best,
--
Allen Cronce

 

I think it says somewhere in the manual that street address location is based on blocks of numbers. So they know where the range [100-600] is but not exactly where 400 is. Consequently I would call it a limitation of the data, not lack of GPS accuracy.

 

In the current location display are the LAT-LONG numbers correct at a benchmark location?

May be a mapping issue and not GPS accuracy?

 

Good question, I'll compare it against my GPS III.

 

The icon in our M35 lags behind too btw. And when I test drove a lexus, it appeared to as well.

My M5 doesn't, but its navi is not as good all around as any of the Japanese car company's.