I have 4.56 gears installed with the yellowbox. The yellowbox is calibrated with a negative 11% compensation to correct my speedometer.

4.56 / 4.10 = 1.11
11 percent increase in revs.

In 6th gear At 5000 rpms my speedometer is reading around 75mph. I think I'm suppose to be at 80mph, right?

Second gear redlines at 50mph according to the my negative 11% compensation setting on the yellowbox. I think second gear should redline at ~59 mph with 4.56 right? Is anyone elses yellowbox off?

I can feel that I'm pacing in the fast lane on the highway at speeds at or above 70mph because I'm passing people, but my speed reads in the 65 range. I highly doubt traffic is going slower than 65.

With this observation, I'm thinking my yellowbox calibration is a few percentages off. Nothing that I can't calibrate for, but my question is does anyone have this same experience?

Thanks.

 

On my Lunch break I will take a look at the switch settings again and report back with the positions of the switchs. This will help make sure I'm not reading my settings wrong either.

 

Of course i may be wrong...It is/was my understanding that with the 4.56 gears on AP2 the calculation came to +11.22% compensation setting for the yellow box.

Your negetive setting would account for what you're perceiving to be diffence in MPH.

Some please correct me if I'm wrong, clarify further or point to mroe authoritative source or thread.

Thnx.

 

You are correct 4.56/4.10 = 1.112195 ~ .1122 as you listed.

I just rounded to 11. 11 percent 11.22 percent...not really going to affect the results I've described. If anything, if I increase it .22 percent more negatively, it would make the speed even more off in the direction it is going right now.

Can you check you switches and tell me what yours are set to?

(edited)
My current switch settings are at
01010011
I was told that the value was set to negative 11. So I have to assume that 0 means on. Check below for what was discovered.
(/edited)

Remember, I'm not asking what the correct percentage is, I'm asking if you have to use a different percentage to compensate for the inaccuracy of the yellowbox device (if it is inaccurate?). Still to be determined on my lunch break.

 

To make it clear.

the eight bits represent

(neg/pos) (16%) (8%)(4%)(2%)(1%)(.5%)(.25%)

 

No question on the numbers.
I think your error is coming about from the fact that your inputting a negetive compensation and i think you're supposed to be putting in a positive compensation.

Check in UTH - FAQ's...several threads discuss yellow box settings.

 

That has crossed my mind too.

I haven't put the time into investigating this until today. I'm going to take note of my current setting and do some redline tests to determine the percentage difference. Numbers ought to add up correct, I hope. Then I can determine what really is going on. Thanks for the suggestion.

 

BTW, it's should be a PLUS (+) compensation. +11.22% to be exact. Then, if you want to dial out the natural speedo error, you'll need to get paced and dial in another 1% to 2%.

 

I should expect the following.

Ap1 Gear.......4.1 top speed ..............4.56 top speed

1....................43 mph.......................38 mph
2...................66 mph........................59 mph
3...................91 mph........................82 mph
4..................116 mph.....................104 mph
5..................138 mph.....................124 mph
6..................165 mph (theoretical)...148 mph

I'll have to find out what my actual results are.

 

I'll try flipping it to positive and see if my redline test gets any closer.
Thanks!