What to believe

[rottodiver]

I run an ecu talk all the time, the speed on the ecu talk is about 5 km per hour slower than the speedo... I have 305,s on the troll, I follow the ecu but do you guys reckon the ecu is accurate or the speedo?

Scotty

[BigRAWesty]

Grab a GPS to confirm. Guessing it 5k at highway speeds?

Kallen Westbrook
Owner of
Westy's Accessories

[rottodiver]

Yeah at 100km/h on speedo it is 95 on ecu talk..... Yeah good call on GPS.. Probably should have thought of that... Lol

[Alitis007]

I'm running stock wheels and my speedo is out for eg speedo 50 = 50 gps, 60 = 58, 70 = 65, 80 = 75, 90 = 83, 100 = 90 and 108 = 100 @ 1850rpm, also when i put it on my ultrascan scan tool i noticed in the ecu it had speed variation ( or something along those lines) 5km/h

[Maxhead]

Try a GPS to compare mate






.........on the move

[04OFF]

The readings 007 gave sound typical, it appeared to me like the GU speedos read well below actual speed, (100kph group tested with GPS) fitting 33s often saw a more accurate speedo reading at 100kph.


On a unrelated topic, can you put up some pics of your car with the 305s please Scotty ?

[Bulbous]

I had exactly the same with my GU and stock tires - 120 on Speedo was actually 108 by GPS. Fitted 33s and 120 on speedo is 118 on GPS - much better
Having said that - the Odometer now under reads slightly.
Checking elapsed mileage with GPS shows that the ODO is not counting the KMs accurately - it's under reading. I can't remember the exact difference but it's noticeable. I'll check and post up later.

[threedogs]

I run 305s and find I need to travel at about 98 by the speedo to sit on 100 by GPS,

[zaid-m]

I have exactly the same problem on my GR/GU, its speedometer is in miles per hour, I've checked it against GPS and is about 10% low at most speeds, So when I am doing indicated 60 miles an hour, actual speed is about 54mph - the only good side of this is at least I won't get a speeding ticket, even if I'm fractionally over the indicated speed limit

[Winnie]

My last GQ was spot on with 33s.this one is way off, 90km on the speedo is really 100km on gps

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