Ok, started new threead for the Kiwi:https://www.jaguarforums.com/forum/s...593#post283593

@milennia man
Did you take the ultra gauge out of the obdii port? Or did you leave it when parked? If connected the device will still get power and may remember the protocol, so you still might need to force it if you disconnect the device.

 

I unplugged it several times when I got the first CEL light. I cleared the codes and started over, plugging it back in. Then unplugged it again when I could not get out of the menu screen. Staying in the menu screen means it stays on forever, like overnight when I noticed it!

I drove the car today and got the alarm and "pending code" warning. The alarm came on about every minute or so. The beep drove my wife crazy, I can't hear it.

I stopped and turned off the audible alarm. It still said pending codes. When I got home and checked for codes, there were none!

I plan on leaving the gauge plugged in permanently.

The problem I had with gauge placement in the layout also seemed to have gone away today when I reset the layout, it all showed up as planned.

I'll try the force protocol, and see if the "pending codes alarm" goes away.

 

Sam, There are various grades of GPS. The consumer variety, such as Garmin or Tom Tom, has reduced capability due to security issues. The military has the genuine article and it is very accurate. This practice is called "selective availability" and is done this way to keep our enemies from using our GPS to attack us as the military has complete control over all US developed GPS. Europe, Russia, China, etc., are all developing their own systems. The airlines are only now getting GPS, as a good friend of mine, who was the chief engineer in developing GPS for the military (he works in the Pentagon and goes by the moniker Mr. GPS), is working on that. Surprisingly no commercial airliners had GPS until very recently. Their ability to land on auto pilot has nothing to do with GPS. My Pentagon friend has some choice opinions of the FAA.

There is differential GPS, which is used to work around selective availability. In this, a GPS receiver is located at a reference point and then a correction signal is broadcast. GPS receivers that have this can improve accuracy if a correction signal is available. The receivers used in general aviation typically have this and most airports are set up to support the correction signal. I assume, but don't know for sure, that the airlines will eventually be using military grade GPS.

The accuracy of your GPS measuring speed going down the highway is highly dependent on how the receiver handles it. For starters at best it can only get a location once a second. The accuracy is also dependent on how many satellites it is triangulating, which depends on how the receiver is mounted relative to the car roof and where the satellites are in their low earth orbits. (The XK soft roof could allow the RF to penetrate). If you are driving down a fairly straight road, and the receiver averages the consecutive readings to neutralize the dither, the speed can be quite accurate. If you are driving on a windy road it will not be accurate.

Regarding speedometer accuracy, you may have noticed that people make a regular habit of changing the tire sizes on their cars. Tires of the same size specification from different manufacturers are also marginally different. Inflation pressure affects this. I'm not sure what the policy from Jaguar has been but tire size is a big deal regarding speedometer accuracy. The wheel sensor can accurately measure the time it takes for the wheel to rotate but converting this into speed requires distance traveled, and that is where the tire size factors in. Whatever the ISO spec is for speedometers, it becomes irrelevant when people change the tires around. Jaguar did offer various wheel options on the XK so I have to assume that there is some mechanism to compensate the speedometer for this (ie calibration). My guess is there is a way to do this through the OBD port.

 

The UltraGauge User Manual spells out exactly how to calibrate the UltraGauge to reflect accurate speed, distance traveled and mpg. It's on page 31 and looks to be a very straightforward method. It is designed to work regardless of your wheel/tire size so you can get extremely accurate data. Here's a screen shot.

 

My test was install the UltraCauge, turn my GPS on and drive down the road at a constant speed and compare all three. The speedometer failed and both the UltraGauge & GPS were on the money. As for the adjustment of the UltraGauge I would only do that if it was confirmed to be inaccurate.

 

Since May of 2000 the civilian and military GPS's have equal accuracy. That's when the government stopped degrading the signal for civilian use of GPS. The "Standard Position Service" which civilian receivers use is now just as accurate as the military's "Precision Position Service". The government still has the ability to degrade the SPS signal when they think it's necessary, but they've never done it, and I'm sure we'd have to be at all-out war before they would do it.


My flight instructor is an ATP. He has about 12,000 hours 737's 757's and 777's. According to him, the jets he flew started using GPS in the late 90's. Heck, I learned to fly in a little, 4 seat Cessna 172. It had a GPS unit in it, but my instructor wouldn't let me use it because he didn't want me to rely on it. He wanted me to learn to navigate the old-fashioned way. I got my license 10 years ago today. I don't know where your friend in the pentagon is getting his information, but he is incorrect.

There are essential two types of instrument approaches at US airports. The old-fashioned kind is called ILS, or "Instrument Landing System". ILS transmitters have to be installed on each runway where the system is going to be used. They are expensive and complicated. A GPS approach, on the other hand, doesn't require any additional equipment on the ground. The FAA creates the procedure specific to each airport, and the GPS units are updated to include the new procedures. If the GPS is coupled to the autopilot the plane can essentially land itself. On small planes the pilot only has to take control for the last few seconds of flight to "flare" the aircraft. On the big jets the software is smart enough to do everything. There are currently 2345 GPS approaches that are approved by the FAA. I don't know how many ILS systems their are in the US, but I promise you it's a lot fewer than 2345.

You're talking about WAAS. Every aviation GPS has been WAAS enabled for at least five years, and there are lots of car GPS's that are WAAS enabled now, too. SPS accuracy used to be <100 meters and PPS accuracy was <20 meters. When the government stopped degrading the SPS signal in 2000 the SPS signal improved to <20 meters, the same as the military's. With WAAS the signal is now <1 meter. That's what allows airplanes to land with GPS. Prior to WAAS the vertical inaccuracy was too large to make GPS approaches safe.

I disagree. The GPS is calculating your speed every second. If you change speed slightly, the GPS picks up the change within the first second. Let's say you're driving 60 MPH on a super-twisty country road. At 60 MPH you travel 88 feet in 1 second. Unless you're driving through a switchback down a mountain pass there isn't enough difference between the chord of your curve and the actual path of the car to make more than a fraction of a percent difference. And if you're doing 60 MPH through a switchback you're probably concentrating on something other than your speedometer.

I don't know the answer to that, but my prior car was a BMW Z3. I was a member of a BMW forum, and one of the big complaints on that board was the speedometer inaccuracy. Everyone complained that their speedometers showed that they were going faster than the actual speed. The only solution was to buy a device that took the pulses from the speed sensor on the wheel and translated those pulses into slower pulses to trick the car into thinking that it was going slower than it actually was. That made the speedometer reflect a more accurate speed. People complained to their BMW dealers, but when BWM would check the accuracy of the speedometers they would always say that it was within spec, even though it showed the car was going 77 MPH when it was really only going 70.

When I sit motionless at a stop light or in a parking lot, my GPS always says I'm going zero. Every once in a while it might blip up to .1 for one second, but that's very rare. If I creep forward a few inches while waiting for the light my GPS will show that I'm traveling 0.1 or 0.2 MPH for the few seconds that I'm rolling. That's how accurate it is. Unless your speedometer has been precisely calibrated, and you're tires are inflated to the exact pressure they were at when it was calibrated, and the tire temperature is the same, and you haven't worn more than a fraction of an inch of tread off of the tires, the speedometer on your car is going to be wrong. Even the cheapest GPS receiver is an order of magnitude more accurate than a car speedometer when calculating your speed.

OK... end of rant. Now let's go get a beer.

 

OK... I'm not trying to beat a dead horse, but I wanted to see what effect driving through a curve would have on the accuracy of a GPS unit. I used Google Earth to get a satellite view of the sharpest curve I could find in the local area. It's an interstate on-ramp that I take at about 25 MPH in my Expedition. I could probably take the curve at 45 in my Jag. I did the math and calculated that at 45mph my Jag would be pulling .61 G's in that curve. So, 45 is doable, but for non-race car drivers like me it would be a little scary.

So here's the curve. It's in the top left. I used my mad Photoshop skill to darken the rest of the image to highlight the area to which I want to draw your focus. Groovy, huh?



Here's a closeup of the curve. I used a couple of tools in Google Earth to draw two lines; one line followed the curve of the road and the other line is a chord of the curve. Google Earth calculates the length of the lines and it shows that the curved line is 185 feet long and the chord is 179.16 feet long. I intentionally picked a line length of 185 feet for the curved line because 45mph is 61.32 feet per second. That means in three seconds a car would travel 185 feet (OK, so I'm a foot off. I couldn't get the cursor to stop at exactly 184 feet).



The difference between 179.16 feet and 185 feet is about 3%. which would be 1.35mph at 45mph. BUT That's assuming that the GPS only calculates your speed every 3 seconds. It actually calculates it every single second, so we have to measure a curve of only 61.32 feet. I did that in the picture below.



So with an arc of 61.6 feet, the chord is 60.75 feet. A difference of only 1.4%. At 45mph your speedometer would say you were going 44.4mph. Most GPS's don't show the decimal for speeds greater than 10mph, so the GPS speed is going to read 1mph off in the worst case scenario.

I then got curious to see how much of a difference there would be between my GPS speed and my actual speed if I could take this curve at 100mph. Here's the plot of the arc and the chord:



100mph is 136 feet per second. So if I could go through that curve at 136 feet per second, the chord of my arc would be 133.76 feet. A different of 1.67%. My GPS would tell me that I'm going 98.33mph rather than 100mph. Not really enough of a difference to worry about. And at 100mph I'd be pulling 2.3 G's in the curve! I know my car couldn't handle it, and if I could do it in a Formula 1 car, I'd be too scared to take my eyes off the road to look at the speedometer.

So, I think this pretty much shows that the chord effect is negligible when using your GPS as a speedometer.

 

Sam: All very clear.

Now, there's this problem of Dark Matter.

Maybe you could tackle that?

 

Sam have you got too much free time on our hands! Ha Ha.
Cool pics and analysis though (I was an engineer among other things in the AF --followed along perfectly)

 

Here I go beating a dead horse again. I put three GPS units in my car the other evening to see how accurate they were in comparison to one another. And being me, I made a video of it. The small green display is a handheld unit that is WAAS enabled, which means it has the potential for 1 foot of accuracy. The speed reading on that one is the second number from the top.

Here's the video: http://www.youtube.com/watch?v=ogeGEMss_Z0 It's only a minute and a half.

 

Can we get back to the Ultra Gauge...I would like to get one?

What is the bottom line? Has anyone gotten it to work without issues once the protocol is entered correctly?

(I read this whole thread before Xmas and don't have the patience to re-read it right now.)

 

I can tell you that I have not been successful in getting the Ultra Gauge to work on my 99 xk8 without faults. I have no use for anything that is not a plug and play, if forcing it to work is what one needs to do I can tell you it is not for me. I did however do a little research and elected to get and test the Bluetooth interface using my Droid 2 and on my first test it seems to work well. I downloaded 4 programs – OBDroid, Voiger Dash, alOBD Scan & Torque. So far all but one worked well on my 2000 s-type and I will be trying it again tomorrow and that was OBDroid (one that I paid for). What was nice was that you could setup a host of screens that fit your needs and use it when you need it provided that you have the interface plugged in and available and you have a PDA that is compatible with the software. I will be testing my 99 xk8 on Monday / Tuesday and will provide you an update then.

 

Steve-
Don't forget the HKS CAMP 2 integrated gauges on the nav screen you were interested in...I am almost done getting the installation perfected and will be sharing my experience. This will let you add Boost, oil pressure and other custom gauges besides OBDII data.

 

Sam,

Terrific writeup on GPS. One small quibble, one gee-whiz fact:

- Last I looked, there were still forced accuracy degradations on certain civilian receivers ... those operating above some specified speed, those operating above some specified altitude. The reasons for this probably don't need stating.

- GPS is at this point (I think) the sole publicly-accessed system in the world which works only because it has built into it corrections both for special relativity (the speed of the satellites) and general relativity (satellite altitudes). The big guy was right after all !

 

I, too, bought one of the bluetooth OBDii tools. I got mine from dealextreme.com. It took about three weeks to get here from China, but it works great. I opted for the one from dealextreme because it is much more compact than the ones I saw on eBay. Here's the one I bought: http://www.dealextreme.com/details.dx/sku.16921

I use it with the Torque app on my Android phone (HTC Evo 4g) and it works great!

 

Ditto for me also. This gizmo looks cheap enough to get just to play around with HOWEVER if it screws something up in the process then fuggetaboutit. From some of the early posts it looked like plugging the UltraGauge in created some faults but it was not clear to me if these were just temporary and disappeared once the unit was unplugged of there was more of a problem.

So I am just looking for some confirmation from those brave souls who have tried this out--is there the chance that UltraGauge can really screw something up?


Thanks,

Doug

 

The ultra gauge works fine on my 1999 XK8.

Initially when I plugged it in it gave a fault. Maybe I didn't seat the plug well, I don't know. I also didn't read the manual prior to plugging it in and I may have caused the fault by confusing the gauge.

The issues I have had are the warning of a pending code, with the alarm going off. There never was a code thrown. I just turned off all warnings. I've had the car out for drives about 10 times and several hundred miles.

It found the correct protocol, I never had to force the protocol.

I have checked for codes several times and there have been none.

I like the gauge, especially the display, easy to see.

I will turn the alarms on again and see if they still say there is a code. But it's cold here in Texas and it may be a week or two before I take the car out. I haven't put the top up since I bought it 3 months ago.

Regards,

Don

 

So it seems MilenniaMan is the only one to get the Ultra Gauge to function without a lot of hassel.

The HKS CAMP 2 in WhiteXKR's car is the ticket. Just I forgot how much it cost. Way more than the Ultra Gauge but i'd be happier with it. So it goes on the Jag priority list someplace.

So how much is it again???

 

Agree if you have the factory nav. or an aftermarket headunit with video...otherwise I'd look at other standalone solutions out there or the PLX Kiwi.

The HKS CAMP 2 is unfortunately quite expensive. It is a permanent, installed, integrated alternative to aftermarket gauges. Besides OBDII displays, it will let you do boost, oil pressure, fuel pressure, and EGT ...none of which are accessible over OBDII. It is purely an electronic gauge system, it does not support code reading or resetting.

The main unit is around $500. Then you need a composite video to RGBS converter, another $200 or so. Add on sensors are about $100 for a six-sensor interface unit and about $60-$140 per sensor, depending on type.

For me, I combined this with an integrated Garmin (upgradeable map!) nav. unit (about $400), with integrated XM radio and traffic (about $175) on the factory video screen. As a combined value proposition, it made sense to me.

There are not tons of this equipment for sale used out there, but I was able to buy some on ebay (I paid under $100 each for both the video interface and the XM radio interface).

BTW, the HKS CAMP OBDII will not work out of the box on 2002 and earlier XK models...it requires a cable modification which I have already posted in the Audio/Visual Electronics section.

 

I eventually bought one for the reasons you mentioned. If it doesn't work it can go to the bone yard with my significant pile of other useless devices. I couldn't get it to work on my 00 XKR after a couple of attempts. I though it was weird that a guy from Ultra Gauge came on the forum and said to force the protocol but didn't say to what. Anyway I moved it to a Subaru and it behaves better there.

Ultra Gauge is geared mainly toward the MPG crowd so I don't see it as a fit for this group. I don't think any of us bought the car with the intent of stepping lightly. In the Subaru I am getting nuisance alarms so I had to turn off the alarms or put up with a lot of beeping. For some reason it says it can't read the fuel level and wants me to enter the value. Try doing that when driving down the road. I think it is a clever idea but in need of refinement. Unfortunately there is no upgrade policy so I think this is headed for the bone yard due to the PIA factor. The KIWI unit looks like a better choice to me once I recover from Christmas.

The suction cup mounting arm might be the best part of Ultra Gauge. That thing works well so I will probably re-purpose it for something else like my add-on satellite radio or maybe the cell phone.