# 2006 speedometer calibration check?



## hornian (Feb 8, 2006)

I've searched the forums, and I can't really find anything that addresses this question. 

On my new 2006 XE KC, it feels like the speedometer reads faster than actual vehicle speed. For example, when it says I'm going 70, I'm going with the flow of traffic on a local highway that usually cruises between 55-60. I'm using the 4-cylinder w/ 5-speed tran., and factory tires/wheels. 

However, it may just be that I haven't gotten used to just how quick the truck is yet, and the fact that it takes so little effort to get up to speed as compared to my previous truck ('01 Dodge Ram) that I'm fooling myself into thinking that I'm going faster than I really am. 

Has anyone else noticed this, and if so, where can I get it checked out (other than getting a cop to radar me)?


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## Arknismo (Feb 3, 2006)

hornian said:


> I've searched the forums, and I can't really find anything that addresses this question.
> 
> On my new 2006 XE KC, it feels like the speedometer reads faster than actual vehicle speed. For example, when it says I'm going 70, I'm going with the flow of traffic on a local highway that usually cruises between 55-60. I'm using the 4-cylinder w/ 5-speed tran., and factory tires/wheels.
> 
> ...




Not sure. Only thought I have is to look for one of the radars the police put out, say around a construction zone. That is my only suggestion. Or get a friend and go out on the freeway and drive side-by-side and see if you are the same. Those are my only 2 ideas. (both free :thumbup: ....unless the radar by the construction zone has a cop behind it!!! :thumbdwn: ....just make sure you check you speed at the speed limit!  )


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## hornian (Feb 8, 2006)

Arknismo said:


> Not sure. Only thought I have is to look for one of the radars the police put out, say around a construction zone.


Good suggestion, but I know that they are often set low to make people slow down even more (at least according to my friend who works for TXDOT).


Arknismo said:


> Or get a friend and go out on the freeway and drive side-by-side and see if you are the same.


 I might try this one, just to see what kind of ball park range I get.

Thanks for the reply.


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## 05 NISMO 4X4 (Jun 4, 2005)

You can also drive at exactly 60 miles per hour and time the distance between mile markers. It should take exactly 60 seconds to go one mile at 60 mph! :thumbup:


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## jerryp58 (Jan 6, 2005)

hornian said:


> I've searched the forums, and I can't really find anything that addresses this question.
> 
> On my new 2006 XE KC, it feels like the speedometer reads faster than actual vehicle speed. For example, when it says I'm going 70, I'm going with the flow of traffic on a local highway that usually cruises between 55-60. I'm using the 4-cylinder w/ 5-speed tran., and factory tires/wheels.
> 
> ...


There's probably a local shop or two in your area that can calibrate it for you.

You could try:



a GPS (if available)
setting the cruise at 60 MPH and see if it takes 1 min to travel 1 mile
check your trip meter (with 10ths) against highway mile markers

Just some thoughts.


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## Centurion (Sep 5, 2002)

This reminds me of a girl at work who had the same problem with a '93 Sentra.
It turned out that the speedometer was calibrated for the Canadian market, so the reading was faster than the speed she was driving and of course the odo was spinning out kilometers, but the gauge face was for the American market. They put in a new speedometer head and that fixed it.


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## MrFancypants (Nov 18, 2005)

OEM Speedometers normally err on the cautious side by around 2-3 mph at 65 mph. That helps with your defence against speeding tickets unless you are running larger than normal diameter tires. OEM Speedometers are also known for decreased accuracy with speed. In other words, the faster you go the less accurate it is. The only way to get truly accurate speed is to use a crank angle sensor that keys off the flywheel. Thats what the ECM uses to limit RPM, speed, etc. and is much more accurate than the speedo in your dash.


- Greg -


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## Outkast (Jan 29, 2006)

It's under warrenty, take it to the dealership if you really think something is wrong.


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## GTIMANiac (Jan 14, 2006)

When using my GPS in the car I have noticed this as well. I have NEVER heard of a speedo being off on purpose. My VW, Audi and Porsche's were all dead on with the GPS.


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## msubullyfan (Jul 24, 2005)

Before you do anything more time-intensive, grab a stopwatch and a passenger and do a few trial runs on the Interstate. 05 NISMO 4x4 is right -- it should take you exactly 60 seconds to go 1 mile at 60 mph.

I suggest doing several trial runs (maybe 2-3 miles each) to get an average of the runs. This will help against any variance in the exact mile marker placement. Also, you can go faster/slower than 60 and adjust for the difference in speed (e.g., it takes 51.43 sec to go 1 mile at 70 mph, etc.).

If you see a significant variation, then take it to the dealer.


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## GTIMANiac (Jan 14, 2006)

msubullyfan said:


> Before you do anything more time-intensive, grab a stopwatch and a passenger and do a few trial runs on the Interstate. 05 NISMO 4x4 is right -- it should take you exactly 60 seconds to go 1 mile at 60 mph.
> 
> I suggest doing several trial runs (maybe 2-3 miles each) to get an average of the runs. This will help against any variance in the exact mile marker placement. Also, you can go faster/slower than 60 and adjust for the difference in speed (e.g., it takes 51.43 sec to go 1 mile at 70 mph, etc.).
> 
> If you see a significant variation, then take it to the dealer.


Are mile markers actually 1 mile on the dot? I kind of doubt it. A handheld GPS should be accurate within a tenth of a mile per hour on speed readings.


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## hornian (Feb 8, 2006)

Centurion said:


> It turned out that the speedometer was calibrated for the Canadian market, so the reading was faster than the speed she was driving and of course the odo was spinning out kilometers, but the gauge face was for the American market.


Well, its definitely not that bad, but I got the same feeling again tonight. Who knows, maybe everyone IS driving faster, and I'm just paying more attention now since I'm in a new truck. 

Also, I think some of it is simply perception. I can barely hear my engine (I actually consider this a good thing), whereas in the dodge you always knew when it was on. 

That said, I have to make a road trip to San Antonio this weekend, so I'm going to do the mile marker test. Too bad I returned my handheld GPS because I thought I wasn't getting enough use out of it.

Again, thanks all for the replies.


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## GTIMANiac (Jan 14, 2006)

hornian said:


> Well, its definitely not that bad, but I got the same feeling again tonight. Who knows, maybe everyone IS driving faster, and I'm just paying more attention now since I'm in a new truck.
> 
> Also, I think some of it is simply perception. I can barely hear my engine (I actually consider this a good thing), whereas in the dodge you always knew when it was on.
> 
> ...


I can assure you it is no just perception. I have almost 2k on the clock now and noticed it on day one of owning it. I do alot of hunting and off roading, so I probably have a GPS on 75% of the time when I am driving. It is about 2mph on average I would say, it does not seem to be off the same through the range of the speedo. At some speeds it appears worse than others. i.e. here in AZ most interstates the speed limit is 75mph. I have to have the speed reading nearly 80 to be doing 75.

One thing I can do is this. I have software that allows me to log data from the ECU/ECM real-time. I can read the vehicle speed data and see how it compares to the Speedo and GPS and ECM together. Only issue is it logs in khm and not mph.


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## inyourface1650 (Oct 6, 2005)

My 05. SE is approximately 5% off. I have tested this against Traffic Radars in New Mexico. There is a bit of road where they have 4 radars set up in a row, and every single one of them was 5-6% off. 

Its rather nice, has saved my ass on some speeding tickets im sure. 

Because i Know about the adjustment, I can go like like 80 (indicated) in a 65 zone and still not get in trouble


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## ScopeTx (Nov 9, 2005)

I did extensive testing on my '05 NISMO against my GPS and some Interstate mile markers. At highway speeds my speedometer registers about 3% slower than my actual speed. 
-Scope


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## msubullyfan (Jul 24, 2005)

GTIMANiac said:


> Are mile markers actually 1 mile on the dot? I kind of doubt it. A handheld GPS should be accurate within a tenth of a mile per hour on speed readings.


No, that's why you do runs of 2-3 miles (or more) and do a minimum of 5 iterations -- to minimize the effects of statistical variation.

Not everyone has a GPS -- myself included.


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## CT_Nismo (Dec 25, 2005)

*Measured Mile*

Every community has a highway with a measured mile. Check with the local DOT or the cops. This stretch of road is 1 mile long so you can calibrate your odo against it. I think GPS will put these measured miles out of business in the far future.

Have you changed tires or rims? The outside diameter of the rolling wheel has a profound inpact on mph.


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## hornian (Feb 8, 2006)

CT_Nismo said:


> Have you changed tires or rims? The outside diameter of the rolling wheel has a profound inpact on mph.


Nope, still running on the factory tires and 15" rims.


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## msubullyfan (Jul 24, 2005)

Just checked mine today on a road trip. Did 6 trials of 3 miles each with cruise control set at 60 mph... It took within 1-2 seconds of 180 sec. each time.


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## NismoFrontin' (Oct 4, 2005)

hornian said:


> Nope, still running on the factory tires and 15" rims.


Put on some bigger tires, like some 31's. That oughta fix it right up. :thumbup:


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## MrFancypants (Nov 18, 2005)

msubullyfan said:


> Just checked mine today on a road trip. Did 6 trials of 3 miles each with cruise control set at 60 mph... It took within 1-2 seconds of 180 sec. each time.


My guess is the speedo is most accurate on the Nismo as that is the largest factory-installed tire. I would expect the smaller tires on the SE and LE will have a larger speedo error. I doubt Nissan has differently calibrated speedos by trim level.


- Greg -


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## mainerunr (Jul 30, 2005)

MrFancypants said:


> My guess is the speedo is most accurate on the Nismo as that is the largest factory-installed tire. I would expect the smaller tires on the SE and LE will have a larger speedo error. I doubt Nissan has differently calibrated speedos by trim level.
> 
> 
> - Greg -


I've had that exact thought. Not only that but with the smaller tires, the odo will climb faster and the mpg numbers will look better. I wouldnt say I'm actively TRYING to kill off these grabbers so I can replace them but I'm not worrying about preserving them either. I'll be going up to at least 265/75-16 when these are done (11k on them so far).


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## CT_Nismo (Dec 25, 2005)

*Speedos and Odos are Accurate*



MrFancypants said:


> My guess is the speedo is most accurate on the Nismo as that is the largest factory-installed tire. I would expect the smaller tires on the SE and LE will have a larger speedo error. I doubt Nissan has differently calibrated speedos by trim level.
> 
> 
> - Greg -


Since the speedo and odo are electronic, all Nissan would have to do is to program the ECU to allow for differences in tire sizes. This is simple. So I don't think the model makes a difference. Aftermarket mods would be the largest cause of inaccurate speedometers.


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## boris (Apr 10, 2005)

with my gps its 3mph slower.


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## msubullyfan (Jul 24, 2005)

CT_Nismo said:


> Since the speedo and odo are electronic, all Nissan would have to do is to program the ECU to allow for differences in tire sizes. This is simple. So I don't think the model makes a difference. Aftermarket mods would be the largest cause of inaccurate speedometers.


Yup. It also means that the speedo and odometer can be adjusted for different tire sizes. Most will even accept non-standard tire sizes if you can find someone who knows how to do the programming.


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## jerryp58 (Jan 6, 2005)

msubullyfan said:


> Yup. It also means that the speedo and odometer can be adjusted for different tire sizes. Most will even accept non-standard tire sizes if you can find someone who knows how to do the programming.


A friend went to have his '03 Jeep Rubicon checked out this weekend. He has 35" tires and wanted to have the ECU recalibrated (I think 32" was stock). They told him that there were three different ECUs used over the years; one couldn't be modified at all, another could be set to one of three pre-programmed tire sizes, and one could be set to match any tire diameter. I guess I'll find out tomorrow which one he has. Oh, they were going to charge him 1hr labor (~$75) to do this. I changed the plastic speedo gear in my Corvette's TH350 once. Relatively easy job and just a $8 or so part, but I guess with the cost of the computers these guys use, $75's not too bad.

It'd be nice if all of the Nissan ECUs were the completely programmable type.


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## MrFancypants (Nov 18, 2005)

So since nobody believed me, I checked the FSM 

"SPEEDOMETER - ABS actuator and electric unit (control unit) provides a vehicle speed signal to the combination meter via CAN communication lines."

Futher down it goes on to describe the troubleshooting process, which involves checking the ABS, ABLS and HDC/HSA/VDC/TCS systems. If they check out fine, the fix is to replace the combination meter. The combination meter is the entire instrument cluster behind the steering wheel. In other words, it's not serviceable and it cannot be calibrated. There is no ECU involved.

Now the only thing that could be possible to vary speed by trim level would be if the combination meter is different by trim level. Someone would have to check FAST to find that out. I dont see why Nissan would bother, since if you change tire sizes from stock it's all irrelevant anyway.


- Greg -


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## hornian (Feb 8, 2006)

MrFancypants said:


> Now the only thing that could be possible to vary speed by trim level would be if the combination meter is different by trim level.


Well, I know that my XE doesn't have the battery voltometer and oil pressure gauge that are in the instrument panel of the higher trim levels, but I don't know if that affects the combination meter.


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## CT_Nismo (Dec 25, 2005)

MrFancypants said:


> So since nobody believed me, I checked the FSM
> 
> "SPEEDOMETER - ABS actuator and electric unit (control unit) provides a vehicle speed signal to the combination meter via CAN communication lines."
> 
> ...


The ability to calibrate the ECU can be done at the factory. With the same hardware, each vehicle can be loaded with different software. The differences in tire size and gearing ratios can be accounted for in the various versions of the software. "Flashing" in a program is a very common method.


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## hornian (Feb 8, 2006)

I did a check on my weekend road trip. It took me about 62-63 seconds (I guess the mile markers aren't all set exactly 1 mile apart, since I didn't get uniform times on each mile) to go a mile with the speedometer on 60. So off, but not as much as I originally thought. Most of it was just getting used to the feel of the new truck.


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## GTIMANiac (Jan 14, 2006)

I had a set of BFG All Terrain K/O's put on this weekend. Instead of 265/70's I put on 265/75's. The speedometer is now within .1 mph of the GPS reading. I am a little surprised that 5% higher on the sidewalls would throw the speedo off by nearly 3mph but it did.


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## 05 NISMO 4X4 (Jun 4, 2005)

GTIMANiac said:


> I had a set of BFG All Terrain K/O's put on this weekend. Instead of 265/70's I put on 265/75's. The speedometer is now within .1 mph of the GPS reading. I am a little surprised that 5% higher on the sidewalls would throw the speedo off by nearly 3mph but it did.


So, are you saying the taller tires have actually made your speedometer where it's displaying your actual speed more accurately?

If this is the case, I wonder how it will effect the calculations of your gas mileage done by the on-board computer?

You'll have to do a manual calculation next fill-up and see how close it so to what's displayed by the computer!


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## landmanlane (Feb 18, 2006)

hornian said:


> I've searched the forums, and I can't really find anything that addresses this question.
> 
> On my new 2006 XE KC, it feels like the speedometer reads faster than actual vehicle speed. For example, when it says I'm going 70, I'm going with the flow of traffic on a local highway that usually cruises between 55-60. I'm using the 4-cylinder w/ 5-speed tran., and factory tires/wheels.
> 
> ...


 If you go 10 miles on the intertstae, by mile markers, and your odometer reads 9.6 miles, your speedometer is probably reading slow, IE , your are showing 70 but you are going 70 X 1.04, for the 4% error, =72.8 mph, and your gas mileage is 4% better, 18 mpg would be 18.72. Or vice versa if your odometer reads 10.4 miles, your speedo is reading fast, showing 70 but 70 x .96 = 67.2 mph actual and your 18 mpg would be 17.28 mpg. Probably more than you wanted to know, but 10 miles works better to make up for possible error in one marker to the next. My Nismo 4x4 is 2.5% off, so my 70 mph odo is really 71.75 mph and showing 19.6 mpg at that speed I'm really getting 19.6 x 1.025= 20.09 mpg at 71.75 moh on cruise ain' bad to me.


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## GTIMANiac (Jan 14, 2006)

05 NISMO 4X4 said:


> So, are you saying the taller tires have actually made your speedometer where it's displaying your actual speed more accurately?
> 
> If this is the case, I wonder how it will effect the calculations of your gas mileage done by the on-board computer?
> 
> You'll have to do a manual calculation next fill-up and see how close it so to what's displayed by the computer!


That is what I am saying, yes.
OEM tires = 265/70/16 -> english measurements 31/10.43
New tires = 265/75/16 -> english measurements 32/10.43


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## mainerunr (Jul 30, 2005)

GTIMANiac said:


> That is what I am saying, yes.
> OEM tires = 265/70/16 -> english measurements 31/10.43
> New tires = 265/75/16 -> english measurements 32/10.43


OEM 265/70r16's if they are the grabbers they are 30.6 (and the math even works out to this).

New tires...well, depends on what they are. 265/75r16 works out to 31.6 but almost every tire out there in that size is a little different.

My odo worked out to be 1.5% high over 31 miles this weekend...so I guess I lose about .3mpg if I correct for that.


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## GTIMANiac (Jan 14, 2006)

mainerunr said:


> OEM 265/70r16's if they are the grabbers they are 30.6 (and the math even works out to this).
> 
> New tires...well, depends on what they are. 265/75r16 works out to 31.6 but almost every tire out there in that size is a little different.
> 
> My odo worked out to be 1.5% high over 31 miles this weekend...so I guess I lose about .3mpg if I correct for that.


Mine came with those wonderful BFG Long Trail's. I trashed one with less than 100 miles on the truck in the desert...


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## landmanlane (Feb 18, 2006)

GTIMANiac said:


> Mine came with those wonderful BFG Long Trail's. I trashed one with less than 100 miles on the truck in the desert...


Verifying what you said, I changed from the BF Goodrich to Michelin LTX, Mud and Snow, same size and I went from 3% error to 2.5% error. I just wanted a quieter tire and I trust Michelin tires. The BFG's only had 1000 miles on them.


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