BadBlackMaxSL

iTrader: (1)

Well, its not major but something that has been bothering me for a while. Whenever I drive by one of those stationary radar signs that display how fast you are going, my reading on the machine is 2 to 3 slower than my speedometer reading. Today I tested it twice, once on the highway and once in a residential neighborhood. On the highway I set my cruise at 70 and the radar said 67. On a residential street I was at 25 mph and the radar said 22. So I tried this test; on a flat highway I set the cruise right at 70 mph, then I reset my trip computer that registers time, distance and average speed while doing 70. Well, my speedo read 70 BUT my computer told me I was doing 68mph!!! I did this for @ 6 miles before I had to brake so I think it is of significant distance to wash out any discrepancies of going up and down slight grades.

Oh, I get the same radar discrepancies in my 05 Pathfinder LE too. Did Nissan build in a little buffer to keep people from getting too many speeding tickets? I mean, if the speed limit is 65 and I am in my Nissan and I am doing "75" per my speedo, I am really doing 72 and most cops won't bust you unless you are at least 10 over the limit.

Both cars are 100% stock so I didn't change the diameter of tires/rims, etc or goof with the gauge clusters. Thoughts?

Ankit69

iTrader: (1)

there is a possibly chance that the machien tellin your speed is off

NismoMax80

iTrader: (6)

i get the same thing. Nissan knows we drive fast and wanted to save us a few $ and points when we eventually get cited.

but tire pressure will have an effect like this. if you compare the SL and SE wheels, they are not an exact match in circumference, so one of the 2 is going to be off.

Longhorn101

I noticed my Max is about 2 Mph off when I'm at 60 mph (radar says 58 when speedometer says 60). The '05 Pathfinder is off by more like 3-4 mph. 2Mph is OK, but 3-4 is getting a little too far off IMO.

I would assume Nissan would adjust the speedometer setting on the SL and SE if the tire circumference is significantly different.

MisterSparkle

iTrader: (3)

damn you really notice these things...i'm paying more attention on behind me or infront of me for cops...lolxz

buh i hope you figure out the problem...buh i mean don't try spending on money on something sooo sm...

Ankit69

iTrader: (1)

damn this means when i got pulled over going 98 in a 55 i was goin 101 hehe

nalc

iTrader: (11)

Maybe the cables controlling it are expanding or contracting because of temperatures?

Jim C

Same here,04 SE .... radar and my GPS sez the same thing,not likely there both wrong by the same amount

lightonthehill

Nissan would make no aduustments to the speedometer based on whether it is being installed in an SE or SL, as the outer diameter of the tire-wheel combo on those two styles is very similar. The SL's higher profile (55) tire pretty much offsets the SE's larger wheel. The official 'ground clearance' and 'overall height' of both the SE and SL are listed as the same.

The only real difference in these two combos is the lower profile tires on the SE have less sidewall for flexing, hence work better than the higher profile SL tires on turns and curves, while the higher profile SL tires have more sidewall to flex, offering a slightly less firm ride.

I have found the speedometers on all four Maximas I have owned (beginning in 1985) were a tad fast; usually around two mph. But then I usually found similar discrepancies in the Studebakers, Chevys, Pontiacs, Oldsmobiles, Fords and Datsuns I drove from 1949 till 1985.

The inflation of the front tires has a tiny effect here, as the distance from the center of the wheel to the ground will be very slightly less with say 30psi than it would with 35psi. But that would not be enough to make two mph difference. Now running with 20psi or less might do it, should tires that seriously underinflated hold together for a mile.

For those of us who are picky, this consistently uniform speedometer discrepancy could be annoying. But it is just something we should be aware of and not worry about.

MAXDOUT04

I'd rather my speedo be slower then faster to save some miles over time.

Blulytes

iTrader: (2)

every speedometer is off by an acceptable margin +/- 4%
Your speedometer is rougly 3.4% off, which is well within acceptable margins of error.

The only true way is to utilize a GPS unit.

This is why you will never get pulled over for doing 57 (+4%) in a 55.

BadBlackMaxSL

iTrader: (1)

Knowing that I am not the only one that this affects makes me laugh. If everything else on these cars are down to the millimeter in specs, etc, I find it funny that the speedo can't get any closer than +/- 4%.

aryathegreat

iTrader: (1)

only a teen would say something like that

Ankit69

iTrader: (1)

hehe well im 18 =)

MIKEDINERO2000

I had my cruise control locked in at 65 on a trip down south. The cop pulled me over and said I was doing 62. I think you are right about the speedodomter.

Ankit69

iTrader: (1)

he pulled you over in NJ ? what county and what cop...

Rathmax

I've noticed this as well. There consistently seems to be a 3 mph overstatement of actual speed. This wouldn't bother me too much except that it means my odometer is reading 5-10% more miles then I've actually driven.

MDS

Every car I owned had an inaccurate speedometer. Like the Max, the speedometers indicated a speed 3 or 4 mph faster than the car was actually going on the highway. Like Blulytes wrote, a 3 to 4% error is normal. I think it sucks. Sorry to say, it also makes the car look like it gets better mileage than it actually does. A 3% error makes the car look like it gets about a 3/4 of mile more per gallon than it actually gets. (That assumes 24 mpg.)

SilverMax_04

Not necessarily so. You are complaining about the calculation of miles per hour. The problem with that calculation may not hold for the Max's calculation of miles traveled. I have noticed that most posted radar speed readings are very close to being "on" for my Max (perhaps 1 mph higher than my speedometer says). But then I run my tires at 35 psi (and as "light" points out, they don't have a lot of sidewall to flex).

I will now have to watch to see what my odometer says when I next hit one of those "measured miles" that some states have on their interstate highways. I personally don't think that my mileage traveled is that far off (4% or so), but I really need to check to be certain.

mwh

MPG is measured by the odometer and not the speedometer. Since the odometer is accurate, your MPG is accurate.

I have found the same as others here for MPH. Many of the cars I have owned have had speedometers that are off a bit. I believe the gov't regulations state there can be a 5% MPH tolerance. I always drive a bit fast and its good to know that I think I am going faster than I am.

MDS

Okay. I had the understanding that the odometer and speedometer received their information from the same mechanism or computer module. Therefore if one was off by 4%, so was the other. But it seems I am wrong. Thanks for the correction. I appreciate it.

Maximam

Mine reads fast too!

queenzkid

The speedometer is off! It will always be faster than american cars (I've noticed)

This is how they get you. Your manufactures warranty will expire a lot quicker! And your car value becomes lower on a resale because the miles are showing higher than they actually are.

Also, it helps Nissan. If someone drives a nissan to 150k miles, it's really 125k. The consumers think the Nissan really lasts that long.

Now that's what's up!

9Nails

My speedometer reads accurate on the bottom of the needle and tires set at 32 PSI cold.

'05 Max SE. Stock GY tires.

SilverMax_04

I believe this error is in the order of +- 2.5% or so and not that big of a deal.

The problem is in the calculation of Miles per Hour (MPH) and not in the miles traveled. So (IMHO) your reporting of higher miles traveled than actual is not happening. The speed calculation can be off and yet the miles traveled calculation can be right on. Try checking your odomoter reading (with the tenths of a mile shown) against the measured mile (or miles) that many interstate highways have. You will find that the miles on your odometer match what the signs show on the side of the road. I would be very surprised if they don't match.

dla

SilverMax
Explain to me how the max gets actual miles traveled?

SilverMax_04

There is a gear in the transaxel (on the drive shaft) that drives the odometer. There is no calculation done, simple a measurement of the number of rotations of the drive shaft. So long as the tires are the correct size (original equipment), this measurement should be correct.

The MPH calculation also measures the rotation of the drive shaft, but this calculation is not just of miles traveled (rotation of the drive shaft), but of miles traveled per unit of time. Doing that calculation is not as simple as only measuring the distance traveled. Speedometers in the USA have historically measured slightly on the high side (fast) -- Nissan continues this practice.

dla

That's exactly what I thought. I was hoping you weren't going to say GPS! Now consider tread wear. A new tire has about 13/32 inches of usable tread. That equals 13/16 inches (.8125) in diameter change. For an SE that means the diameter goes from 26.68 inches to 25.87 inches (if the tread was used to the wear bars) and that's a 3% diameter change just in tread wear. Now add on the more difficult calculation of mph through the drive shaft sensor and I could see a potential of 4% error.

fyi: US federal standards allow a maximum of 5% error in speedometer readings.

SilverMax_04

The gearing for the odometer is not set for brand new tires but for tires with some wear on them. So as the tires wear, the odometer reading goes from slightly short (bigger tire diameter than the gears are set for) to slightly long (smaller tire, etc). I am assuming your calcualteions are correct -- they seem so without me going into the details. So in this case the odometer error should never be more than about 2% and generally in the range of +- 1% or so. Also over the life of the tires, the mileage should be about correct in total -- which was the worry I was trying to address.

I hope that the Max's speedometer is not anywhere near the maximum allowable error of 5% -- will check mine next time I hit a "measured mile" on an Interstate and drive a mile at a speedometer determined 60 MPH. If the speedometer is completely accurate this will take 60 seconds to drive one mile. If the speedometer is 5% slow that mile will take me just over 63 seconds to cover a mile at an indicated 60 MPH (actual 57 MPH). A stop watch would be best to make this measurement. Since I don't know of any measured miles in Colorado, I'll have to wait until I hit one in another state.

lightonthehill

The tread depth on the tires on my last three Maximas measured 11/32nds of an inch when new, and had the wear bars at 2/32nd inches. That is 9/32nds of an inch of usable tread.

That 9/32nds applied to both sides of the tire means a loss of approximately 18/32nds in total outside diameter during the full tire life. That is just over half an inch.

Of course, if Nissan did indeed set the speedo based on the 'half-wear' size of the tire, then tire wear drops out of the speedo calibration picture, other than as a possible consideration if one was trying to check out the speedo on either new tires or tires that were almost worn out. Even then, the effect of tread depth is not great.

Killah Kane

I have noticed this also. I have a TOMTOM navigation unit and when in use, it tells my my speed and it is alwasy about 3 miles less than what my speedometer reads.