Speedomter / Gear Ratio Change

blkblazer · Post by **blkblazer** » Thu May 04, 2006 9:20 am

New to tuning. I have a 93 chevy blazer with 5.7. I recently changed the gears to 4.56. Does anyone know how to modify the speedometer reading for the new gears?

Post by **Mangus** » Thu May 04, 2006 12:25 pm

Most masks don't allow you to change speedo calibration in the bin. What mask does your Blazer use?

blkblazer · Post by **blkblazer** » Thu May 04, 2006 2:00 pm

I think it is $E6

Post by **Mangus** » Thu May 04, 2006 2:08 pm

You'll probably have to add the parameters to the XDF. Here they are:

Code: Select all

			************************************
			* SPEED SENSOR CALIBRATION PARAM'S
			* &#40;2^14 TIME BASE&#41;
			************************************
	
     		;
     		; LAG FILTER CONSTANTS
     		;
L5A0F&#58;	FCB	64 		; 87 msec, RPM filter
L5A10&#58;  FCB	252 	;  6 msec, Input SPD FILTER 
L5A11	FCB	252 	;  6 msec, XMISH INPUT SPD FILTER 

L5A12&#58;	FCB	1   	; 20 msec MAX PERIOD BETWEEN XISH OUTPUT PULSES

L5A13&#58;	FDB	43691 	; 40 PULSES/REV OUTPUT SHAFT SPD
					; 1092.3 usec/bit 
		
L5A15	FCB	252		; 6 msec, Xmish output spd filt


           	;
           	;  GEAR RATIO'S
           	;
L5A16&#58;	FDB	44564 	; 2.72&#58;1 4WD LO RATIO
					; VAL = RATIO * 16,384

L5A18&#58;	FCB	45773 	; 44.7&#58;1 NO/VS RATIO  <------------****		
					; VAL = RATIO * 1024

L5A1A&#58;	FCB	252 	; 6 msec, Vss filter

blkblazer · Post by **blkblazer** » Thu May 04, 2006 2:22 pm

That was fast

So do I cut and paste the params into the XDF file? Or how do I add the additional info? I hope this isn't a bothersome newbie ?

Post by **Mangus** » Thu May 04, 2006 2:44 pm

http://tunerpro.net/tutorials/CreatingECUs.htm

The info is a bit outdated (old version of TunerPro), but the takeaways are the same.