Inaccurate speedo reading

[Harrods]

Hi guys,

 

Would like to find out how to resolve or repair this issue.

 

I drive a honda stream (bought 2nd hand). everything is fine except that the speedo is inaccurate. My speed on my GPS is 100km/h my speedo would read 125km/h. i know that the gps reading is not v accurate as well but when driving with my friend he also confirmed that he was driving at 80km/h when my speedo reading had reached 100km/h +-

 

i realised that the rims were upgraded my the previous owner to 17" from 15".... is that the cause?

 

i asked kah motor (as it was a kah motor stream), they told me the cant help me coz its not a common problem. Try to do a bit of research on the web but then some suggested to change whole consol.....

 

any1 had this problem before?

 

Thanks

[Hamburger]

what is your present tyre size compared to the original?

 

speedo seldom spoilt one.

[Blue850r]

Nothing to do with Rims or tyres because it can't make such big difference.

 

Your Gearbox has been replaced before. The Ratio and final drive is not correct for your car. So the sensor output is not calibrated for your speedo. Don't bother solving it.

[Myxilplix]

Check original rim/tire size for your car vs the current rim/tire size, might explain the variation. Take note that most speedos overread anyways.

[PengYou]

Hey! this may well explain for those road Hoggers on Lane 1.. maybe their speedo already showing 110 when they are only actually at 80km/h.. given benefit of doubt.

[Happily1986]

Nothing to do with Rims or tyres because it can't make such big difference.

 

Your Gearbox has been replaced before. The Ratio and final drive is not correct for your car. So the sensor output is not calibrated for your speedo. Don't bother solving it.

 

 

how you know his gearbox has been replaced? can anyhow change with another/third-party one??

 

i was thinking something more simpler like rolling diameter is off by >5%, therefore the speedo is inaccurate.

[Shibadog]

Check original rim/tire size for your car vs the current rim/tire size, might explain the variation. Take note that most speedos overread anyways.

 

 

yup most speedos overread by 5-10%. The other likely contributor is using tires with smaller rolling diameter than stock. TS can get the tyre calculator here

[Nicholas]

Try:

 

[Blue850r]

how you know his gearbox has been replaced? can anyhow change with another/third-party one??

 

i was thinking something more simpler like rolling diameter is off by >5%, therefore the speedo is inaccurate.

Because I had this experience before.

 

Tyres and rim size at most defer by 5% to 8% max. If Honda Stream original size as in overall diameter is say 215/45r17, TS couldn't be using 235/60r17 or something like that right.

 

So it is the gearbox. As you may be aware Honda 1.7L or 1.8L engine is used widely in Stream and Civic and also sold to many different countries. The gearing for Stream and Civic may be different due to load. We have also come across lower cc cars have shorter gearing while higher cc cars usually have a taller gearing.

 

In the gearbox, there is a speed sensor and it emits pulses to the ECU to indicate the rpm on input shaft from engine. The ECU has a pre-programmed data to convert this rpm to the corresponding speed based on gear ratio and tyre size say for a Stream 1.8L. However, if the gearbox came from a 2L stream or 2.4L stream available from another country, the sensor speed giving out the speed pulse rate but ratios of gear is different. Sounds a little confusing.

 

Take an example: Where gearbox ratio is different or final drive ratio is different.

 

Stream 1.8L engine 3000rpm on 4th gear = 110km/h

Stream 2.0L engine 3000rpm on 4th gear = 130km/h

 

You can see the ECU will have to give a different readout on speedo although the speed sensor still reads input shaft at 3000rpm. But output shaft speed is already different. One is faster than the other.

 

 

 

[Yrvsport]

it invincible don't bother much of notice...GPS reading always is much slower 10 - 15 compare to your speedometer...

[Moadia]

Nothing got to do with the car.. its the gps..

[Watwheels]

I also think the gearbox had been changed to one which dun belong to the stream.

[Silverfern25]

Hi Harods,

 

I encountered the same problem as you when i bought my 3yrs old second hand stream 2yrs ago. Apparently the previous owners have upgraded the rim to 18inch!

 

I discovered that the speed reading is not accurate when even lorries and vans started to overtake me on KPE when i was supposed to be travelling at 80Km/h

 

The speed also does not tally with my GPS readings.

 

I went KAH motor (Ubi) and sadly they told me warranty has been voided as the ex owner did not came for servicing. And the inaccurate reading is due to the rm size.

 

They need to replace the whole panel as it come in a set and are linked electronically. Price is $1K!!

 

I called up the dealer and intially they refused to pay but i nego and ended up splitting the cost. 50- 50. :(

 

So etiher you can live with the speed difference or change it. I find the wrong reading very irritating. That's why i went with it.

 

But there is the lemon law. You can check if this applies.

 

After changing the speedo and downsizing to 17 inch.. the readings are ok.

 

[Ungtiong]

use the ODBII sensor to get the speed reading to see if its the speedo. Most manufacture all get the speedo tolerance higher (its ++ instead of +-) for safety reasons.

 

My ODBII (ECU) speed and GPS speed is almost the same..my speedo reading is about 10% higher.

 

Also very funny i found out my Altis gear ratio is optimized for 0 to 80km/hr....cause its take SO LONG to go from 80 to 100 (real speed)

Edited March 27, 2013 by Ungtiong

[Happily1986]

i see. i am not aware that the same spec gearbox for the same model could have a few variants in the parts bin. i mean say 5 speed auto for Stream, there could be two variants. if the fella changed from a 5 speed to a 6 speed auto, i think that would make sense but i dont know if honda cars are that modular.

[Blue850r]

As long as the engine is the same series, the bell housing of the gearbox is likely to be the same. The centre spline is also likely to fit. However the workshops will know if it fits but not if it gives the correct speed reading.

[Bensonawyong]

Changing rims size will affect the actual speed and speedo reading.

 

Even if all original rims, GPS and speedo reading will not be the same also.

[Chucky2007]

Very informative, thanks for sharing.