Accord speedometer inaccuracy

Have you noticed that the speedometer on your Accord is inaccurate?

One day as I was driving past one of those radar speed-checker rigs (that
the police place at various places to display the speed of your vehicle as
you approach it), I noticed that it did not match what the vehicle
speedometer displayed. Later, I drove by others (in other places/cities) and
noticed the same thing. Then on a trip one day, I asked the occupants to
take measurements/timings and calculate the speed based on straight
stretches of mile-markers.

Apparently the speedometer is about 5 to 7 percent too low in displaying the
speed. For instance, when the speedo displays 65, the calculated speed is
about 61 or 62. Now I could (and do) mentally adjust for this, but it got me
to thinking about the mileage that the odometer is displaying. If the speedo
is displaying on the high-side, then the mileage displayed by the odometer
is too high.

Note, that even though I have gone through one set of tires, I am still
running exactly the same make/type/size of tires that came on the vehicle,
as it arrived from the factory.

I wonder if other Accord owners are experiencing the same? If you have the
same year/type/engine, you should check this. BUT, even if you have
something newer or a different model you might want to check. Why?

If your odometer is logging miles faster than it should, and if anything
goes wrong with your vehicle and it occurs just after your vehicle is out of
warranty, then isn't Honda charging you when they shouldn't be? I would
think this sort of situation, if in fact it is widespread, would definitely
raise a few eyebrows in the federal government, and in the general buying
public.

What say you Honda owners? Are you running a stock vehicle, i.e. no changes
to anything, including tires? Is your speedometer reading too high by an
appreciable amount?

BTW, in case you are wondering -- this is the only Honda I have owned. It is
the best vehicle I have owned. I would buy another, but I do want my speedo
and odometer to be more accurate.

Jon B

 

I would absolutely not count on mile markers as accurate distance
measurements. They are intended to be reference points, not accurate
distance measurements. I suggest putting one of those handheld GPS
units on your dashboard, as I did.

Do you mean to say that your speedo is too HIGH?

Good question. Another poster here has said that they're separate
and independent instruments. I'm not sure.

My Accord speedo overestimates by about 3%. I have 185's on my car. If I
put 195's on my car, it I reckon the speedo would underestimate by 2.5%.
My theory is that the speedo is calibrated to give reasonable accuracy
using both 185's and 195's.

 

that pretty normal, on ALL cars. better too low, than too high. think of it
as an extra margin for avoiding speeding tickets.

 

I can't manage to maintain a constant speed with the speedo right on a
mark for me to judge the accuracy using that method.

On the vehicles that I have checked since I got my GPS, the odometer is
correct according to both the GPS and the mile markers.
The speedometer agrees exactly with the GPS on a BMW motorcycle, a Mustang,
a Dodge Durango, and my Honda Civic.

On the BMW, different size tires threw the odometer and speedo off.


In California, the little paddle roadside markers are accurate to
within .001 of a mile. If there is a variance because of a bridge or
something, that paddle won't be installed. If you measure using those
for a distance of 10 miles, you should have a very accurate reading.
The roadside cell phone markers are only accurate to .16 of a mile,
even though they have .01 numbers on them. If there is a bridge or
overpass, the pole is placed at the most convenient spot.

 

Some of the radar speed checkers are grossly inaccurate.

 

I've compared my new Accord with a GPS sitting on the dash, and it is
right on the money. Distance seems to be pretty close as well. Again
both the GPS and odometer read about the same after a lengthy drive.

I had a 89 Dodge Caravan and the speedometer was noticeably off. I
asked the dealer to check it (under warranty) and he said it was
within factory specs which he stated was with 10% of the true speed. I
know that's what he said because I made him repeat a couple of times
because I couldn't believe he'd be saying that a reading of 77 when I
was going 70 was an acceptable variance.

I have no idea whether he was correct and what Honda's policy on this
might be. I agree with another poster that they probably work hard to
make sure the speedometer reads correct or higher, ie, you are going
no faster than what it says.

 

Apparently the speedometer is about 5 to 7 percent too low in displaying the


they are allowed a 10 percent tolerance either way by law.. if
the speedo quits working the odo still works though.
have the dealer pull up the service news on speedos, it's all in
there.
Chip

 

"J Beierle" wrote

Mine's the Garmin eTrex Venture. I like it, and it has lots of functions to
play with. It sells for about $170.

Howard Lester

 

I have the Garmin Legend which works well for me. The only things I
wish it had are 1) larger memory options, 2) option for a remote
antenna connection.

I have the MapSource product to download detailed maps of the areas
where I am traveling. While 8 Meg has been sufficient for me so far,
in a couple of cases, it was barely sufficient. I think the next model
up has 24 meg ... a huge difference.

The GPS has to have clear view of the sky to work properly. That's OK,
but often puts the GPS in a less than ideal use location. For example,
I use it on airplanes as it lets me know what i'm actually looking at
out the window! But I have to hold it up against the window to work.
In the car I just put in on the dash. However, I'd prefer to be able
to put it in a viewable position on the plane or car. A remote antenna
would allow me to do that. I was on a plane with a guy who had a GPS
he used in his private plane. It had a remote antenna (looked
basically like a wire with a suction cup on the end) which plugged
into the unit. We then were able to view the maps on the GPS away from
the window.

 

I have the Garmin eTrex (yellow/basic) often less than $100. It doesn't
come with a cable to connect it to a computer. If you are interested in
that, which you eventually will be, it can be made up for less than $10.

On the other hand, if you will always have a laptop, and want to use it
primarily for navigating in your car, a cool setup is the new Delorme
Earthmate USB. It's a little pod that could be put on the dashboard, and a
USB cable to connect it to the laptop.

http://www.delorme.com/earthmate/configlaptop_info.asp
With Street Atlas 2004, $129.95.

 

In some places, speedometers are not allowed to read lower than the
actual speed, even if larger tires are installed.

 

| it gives more wiggle room when installing different sized wheels.

Car makers should give buyers 2 or 3 changeable scales for
speedometer's calibration reading, for different size tyres.

 

Does the above price include their Street Atlas software?

I have the previous model of this and love it. I bought my laptop for
traveling and have used their mapping software for years. GPS is
unbelievably accurate (assuming your unit can receive sufficient
satellites), it's a real knock-your-socks-off technology.

One possible advantage to the laptop approach is that the route taken
can be saved in a file for later use, analysis, etc. DeLorme has a voice
option, which I haven't tried yet. I have used Neverlost on Hertz cars
and that was great, basically directing you along the route you entered.
With mapping software like DeLorme's you can enter any street address in
the US and it will calculate a route to get there. I find I don't always
agree with some details, e.g., how to get onto the NJ Turnpike from my
house; but it's really good overall.

 

Hmmm... not so sure about that, at least as a blanket statement.

A friend of mine has a 94 Accord (I4/AT, Canadian) with a faulty
speedo. Intermittently - although recently more often than not - the
needle just sticks at 30km/h and doesn't move up or down. During this
time, neither his trip meter nor odometer advances.

This (dependency) may vary from one car to the next...?


Kevin

 

Exactly analogous to the fuel gauge that always reads "E" before the
tank is truly empty.
Ron

 

a 94 has a mechanical odo driven by the speedo which is electrical.
i've encountered many of those. he needs a new speedo head.

 

"Earthmate GPS for Laptops

Never Get Lost Again!

Includes Street Atlas USA 2004 software for only $129.95


"

 

My 99 Accord EX is exactly the same. A couple years ago we went to the shore
on vacation and took all 3 vehicles. After arriving I asked my wife why she
was doing 75 through Delaware after seeing cops pulling people over. She
said she was doing 67 - 69 but not higher. My daughter in her Saturn agreed
with my wife. As we have 2-way radios we did speed checks on the way home
and sure enough the faster we went the more my speedometer was off.

I am on my second set of tires and it is the same. So now instead of going
3-5 over I go about 7-8 over. And I always thought my Accord was extra
smooth on the road at high speeds!! lol It is still a very nice ride.

George

 

| > Is your speedometer reading too high by an appreciable amount?

If you know your gear ( top & final ) ratios, & you measure the height*
of axis of drive axle, you can calculate cruise speed @ different rpm.
* will drop with cargo / users' weight, rise with tyre pressure when tyres
heat up.
E.g. for a '90 accord @ 3000 rpm : calculation of ratio ( 0.731 x 4.285
= 3.1323 ) will imply that tyres will spin 3000 ÷ 3.1323 = 957.76 rpm
= 57465.75 rph.
If tyre's effective radius* = 30cm ( for a 205/65R15 @2.3kg/cm² ) then
tyre's effective circumference is 44/7 x 30cm = 188.57cm = 0.0018857
km,
Cruise speed ( assuming 100% grip, zero toe-in ) is 57465.75 rph x
0.0018857 km = 108.36 kph = 67.33 mph
70 mph will need 70 ÷ 67.33 x 3000 rpm = 3118.9 rpm.

 

Mine's almost identical. It's about 27-28 indicated for 25 mph. I own
a 1994 Civic coupe DX.

Nate