VE Speedo inaccurate???

[Reaper]

lol what the? A GPS is more accurate than any car speedometer, even more accurate than most police speed detection equipment. How can it NOT be accurate?

In various places where my GPS only gets limited satellites it does take a little while to update. I suspect it is in the software as I would think it should only need 3 to operate. For normal driving i'd say it is within 1km/h at any speed less than 110. (never really tested higher than that).

Reaper

 

[efryer]

Definitely outside stated specs (if we can confirm them)

Don't waste your time arguing with Holden re the accuracy of your speedo or fuel gauge.
Holden specification for the speedo is 60 -0 /+2 km/h
100 -0 /+2 km/h
160 -0 /+3 km/h

Benboy,
Where did you get the Specification on the Speedo. Can't seem to locate anything on stated accuracy.

I agree on the Fuel guage, the VZ was a shocker, but it did force them to update the software more than once to get it a little more accurate.

If you look at my figures that I quoted on what I have found, you will will find that I am outside of those tolerances. I ran another test with actual speeds that they rate the speedo at, and I get the following....

at 60km/h showing 63km/h (+3)
at 100km/h showing 104km/h (+4)
at 160km/h (not worth losing licence)

Definitely different from the Specs that "Holden" are quoting.

Also those specs that you quoted would be exactly how I expect the numbers to be, a slow exponential curve maintaining reasonable accuracy. However based on the figures that I see, they actually appear to be linear, increasing at a fixed rate as the speed increases.

I honestly think that they couldn't be bothered writing the software correctly, and went for a quick and simple % figure.

Grantisaac,
In regards the GPS accuracy. They are actually very accurate in their speed measurements. Almost everyone else claims that they are well within 1km/h, with the following rules
1) Straight road (Freeway is pretty straight)
2) No buildings on road (Again freeway is very clear of buildings)
3) More than 5 satellite fixes (thats why the only tests I run 7+ satellites)
4) Flat road (not undulating)
5) Decent Dedicated GPS Unit, not a GPS in a phone.
As I previously mentioned the same GPS in the VZ was within 1km/h right across the legal speed range.

NeilF,
I was trying to run some tests on this, but on the freeway, there is the normal 5km test poles, but each time I have found it, I have been in traffic with trucks, however, initial thoughts based on some of the measurements, does appear to show it being out by a small margin, whereas again the VZ definitely was tested against this and was spot on accurate each time.

1991_Vn2nV,
I agree with you on the variance of Wheel rim and tyre choices now available for the VE, and the possible impact it may make on the speed, however as a lay person, I was under the impression that this is taken into account by rim and tyre choices correctly matching. As a Guide the VZ came standard with 15", yet the Equip version came with 17" (which is what I had), yet my speedo was still accurate. I agree with a small tolerance for wear as well, but not the 4km at the 100Km/h mark.

This is why I am trying to gauge if this inaccuracy is right across the range of VE Commodores, across the range of tyre sizes, whether anyone has raised it before.

I will raise it at my next service, probably a few weeks away at the moment, and will let you know what is said. No harm in someone raising it earlier, if their service is due. Anyhow any further comments, please add.

Regards
Bob

 

[1991_Vn2nV]

1991_Vn2nV,
I agree with you on the variance of Wheel rim and tyre choices now available for the VE, and the possible impact it may make on the speed, however as a lay person, I was under the impression that this is taken into account by rim and tyre choices correctly matching. As a Guide the VZ came standard with 15", yet the Equip version came with 17" (which is what I had), yet my speedo was still accurate. I agree with a small tolerance for wear as well, but not the 4km at the 100Km/h mark.

This is why I am trying to gauge if this inaccuracy is right across the range of VE Commodores, across the range of tyre sizes, whether anyone has raised it before.

I will raise it at my next service, probably a few weeks away at the moment, and will let you know what is said. No harm in someone raising it earlier, if their service is due. Anyhow any further comments, please add.

Regards
Bob

Rim and tyre choices never match exactly, for example there were two different sizes for the VN...185/75 H R14 and 205/65 H R15 which makes the difference in overall rolling diameter between the two combinations 14.4mm which represents a 2.3% difference in speedo accuracy... So at 100km/h the two cars speedo's would differ by 2.3km/h.

They do try to compensate with the tyre size, but as the tyre sizes are only limited it is never completely accurate.

If the Holden spec is off by 2km/h at 100 and your speedo is off by 4km/h then in my opinion it could very much be dependant on the tyre and rim combination as you're looking at a similar difference added on to the Holden specifications as the VN range of 2.3km/h if not more (due to the larger spread).

 

[Doctor Bob]

They do try to compensate with the tyre size, but as the tyre sizes are only limited it is never completely accurate.

The tyre size is programmed into the car systems & must be updated with a wheel change.
i will try to look up the actual spec for allowable error & see if i can find it in print somewhere.

Rob

 

[Reaper]

Rim and tyre choices never match exactly, for example there were two different sizes for the VN...185/75 H R14 and 205/65 H R15 which makes the difference in overall rolling diameter between the two combinations 14.4mm which represents a 2.3% difference in speedo accuracy... So at 100km/h the two cars speedo's would differ by 2.3km/h.

They do try to compensate with the tyre size, but as the tyre sizes are only limited it is never completely accurate.

If the Holden spec is off by 2km/h at 100 and your speedo is off by 4km/h then in my opinion it could very much be dependant on the tyre and rim combination as you're looking at a similar difference added on to the Holden specifications as the VN range of 2.3km/h if not more (due to the larger spread).

Mine has the original wheels and tyres on it. It was out when it was new.

Reaper

 

[Doctor Bob]

Don't waste your time arguing with Holden re the accuracy of your speedo or fuel gauge.
Holden specification for the speedo is 60 -0 /+2 km/h
100 -0 /+2 km/h
160 -0 /+3 km/h

The figures quoted are the allowable difference between the dash display & the speed shown by the PCM in the datalist.

still looking for the specs

 

[Lost_Pete]

Of interest might be this;

AUSTRALIAN DESIGN RULE 18/03

INSTRUMENTATION

5.3. The speed indicated shall not be less than the true speed of the vehicle. At the test speeds specified in paragraph 5.2.5. above (40 km/h, 80 km/h and 120 km/h in your case), there shall be the following relationship between the speed displayed (V1 ) and the true speed (V2).

0 ≤ (V1 - V2) ≤ 0.1 V2 + 4 km/h

I read this as;

your speedo at 100km/h should read between 100 and 114km/h. (There is another 0.5% accuracy thrown in there for the master instrument if you are really fussy.)

 

[ChrisJ]

I had the same problem with my VE but not with my VZ. The VZ is spot on with my GPS and with roadside radar displays. The VE speedo shows 3km/h more than the GPS and radar at 60km/h and 5km/h more at 100.
The VE has standard wheels and tires as delivered and are inflated to the correct pressure.
I asked Holden to look at it on the last service and they said that it was within tolerance. The service manager also told me that it would get better as the tires wear down, but quickly retracted that when I told him that tire wear would reduce the diameter and make the problem worse.
Basically, they said there is nothing they can/will do about it.

 

[CSP]

The service manager also told me that it would get better as the tires wear down, but quickly retracted that when I told him that tire wear would reduce the diameter and make the problem worse.

They really are almost as low as used car salesmen and it's a shame it's the local dealers that are responsible for service operations and NOT Holden.

They really do think they can tell anyone anything at all! I hate them so much!

 

[efryer]

So my findings are confirmed....

I had the same problem with my VE but not with my VZ. The VZ is spot on with my GPS and with roadside radar displays. The VE speedo shows 3km/h more than the GPS and radar at 60km/h and 5km/h more at 100.
The VE has standard wheels and tires as delivered and are inflated to the correct pressure.
I asked Holden to look at it on the last service and they said that it was within tolerance. The service manager also told me that it would get better as the tires wear down, but quickly retracted that when I told him that tire wear would reduce the diameter and make the problem worse.
Basically, they said there is nothing they can/will do about it.

Thanks, that is what I am after. It shows the issue is throughout the VE range and your figures tally with mine.

Sounds like they have a software fault or there is something more, as some one said (to help improve the consumption figures).....

My VE is only 2 months old, correct pressures, newish tyres, absolutely stock VE SV6 from the dealer.

The 4-5Km/h variance at the 100/110Km/h range is just a bit too much.

Regards

Bob