LS Swap w/ Dakota Digital 8k pulse generator

*Solved*

Here's the story: I have a 1984 K10. I swapped in a 2001 5.3/60e and kept the original '84 NP208 transfer case. I needed a simple way to generate VSS pulses for the PCM and also retain the original cable drive for the mechanical speedo. I chose the Dakota Digital SEN-01-4160 Pass-Through Speed Pulse Adaptor. Problem is, the DD pulse generator produces 8 pulses per speedo cable revolution (or 8000 pulses per mile). The PCM wants 40 pulses per output shaft revolution. Here's the math to solve the discrepancy.

First, apply the 31? tire size (30.5 actual) and 2.73 axle ratio correction to all the shift tables using the "Gear/Tire Wizard." Leave the 40 pulse per trans rotation setting alone for now.


Trans revolutions per mile:
Tire size (30.5" diameter, OR 684 revolutions per mile) multiplied by the axle ratio (2.73), will result in 1867.32 drive shaft revolutions per mile. *Calculated by Gear/Tire Wizard*


VSS P/Rev - Trans:
8 pulses per rev (Dakota Digital output) DIVIDED by 1.9444 (35 driven / 18 drive) from the speedo gear output. Equals 4.11438 Pulses per trans revolution *Manually calculated*


VSS Pulses per mile:
1867.32 (drive shaft revolutions per mile) DIVIDED by 1.9444 (sensor revolutions per driveshaft revolution). Equals 960.358 sensor revolutions per mile. 960.358 (sensor revolutions per mile) times 8 (Dakota Digital pulses per revolution output) equals 7682.864 Pulses per mile. *Manually calculated*



That's it. No welding reluctor rings to output shafts. No drilling speed sensors into adapter housings. Just a $50 pulse generator and 15 minutes to instal it. The numbers are specific to my application, but it's easy enough to plug in different values for another set up. Big thank you to Brendan at LT1Swap.com for walking me through this.

https://live.staticflickr.com/932/41...0231525d_b.jpg

The Dakota Digital Help Desk could answer this question in a nanosecond and explain the mathematics. They were very helpful with my DD HDX set of gauges.

Rick

When an LS conversion involves a vehicle that uses a cable driven speedometer, generating a useable VSS signal is optimal. There are two readily available means of generating a useable VSS signal to the PCM (computer) - a cable driven VSS generator or a GPS unit that outputs a pulsed VSS signal (Dakota Digital offers both of these options).

The most common cable driven VSS pulse generators output 8000 pulses per mile (8K PPM), or 16K PPM. These lower PPM rate generators will sometimes cause issues with torque converter going into a fully locked state - excessive slip can sometimes be an issue. This potential phenomena seems to vary platform to platform, or OS to OS - there is no doubt a "hidden" diagnostic table somewhere within the calibration.

A cable driven VSS pulse generator that outputs at least 40K PPM (some options can go as high as 128K PPM) will operate problem free for all applications, and is a better option.

That said, you already have an 8K PPM VSS generator - so here is how to set it up. Once operational, monitor TC lockup and slip RPM to determine if your specific application is fully locking the TC - or if there is excessive slip occurring.

Step 1 - make certain the speedometer cable drive has been properly calibrated for your gear and tire combination. GM cable drive speedometers require the cable to rotate 1000 times per mile. This calibration is achieved by ratio of the number of teeth on the speedometer drive gear (on the transmission output shaft or transfer case shaft), to the number of teeth on the speedometer driven gear (typically mounted to the transmission tailstock or to the transfer case).

Step 2 - setup the parameters in the PCM software as pictured below. After entering these values, the PCM will accurately interpret the signal from an 8K PPM VSS pulse generator (as long as the speedometer cable is rotating at 1000 PPM). After these changes, you CANNOT use the software to automatically scale the transmission shift speeds - you must now do this MANUALLY - table by table.

Attachment 95043

Quote:

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Originally Posted by B52bombardier1

The Dakota Digital Help Desk could answer this question in a nanosecond and explain the mathematics. They were very helpful with my DD HDX set of gauges.

Rick

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Hadn't even thought of contacting them. Just sent an email to their support desk. Thanks!

Quote:

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Originally Posted by Jon S.

When an LS conversion involves a vehicle that uses a cable driven speedometer, generating a useable VSS signal is optimal. There are two readily available means of generating a useable VSS signal to the PCM (computer) - a cable driven VSS generator or a GPS unit that outputs a pulsed VSS signal (Dakota Digital offers both of these options).

The most common cable driven VSS pulse generators output 8000 pulses per mile (8K PPM), or 16K PPM. These lower PPM rate generators will sometimes cause issues with torque converter going into a fully locked state - excessive slip can sometimes be an issue. This potential phenomena seems to vary platform to platform, or OS to OS - there is no doubt a "hidden" diagnostic table somewhere within the calibration.

A cable driven VSS pulse generator that outputs at least 40K PPM (some options can go as high as 128K PPM) will operate problem free for all applications, and is a better option.

That said, you already have an 8K PPM VSS generator - so here is how to set it up. Once operational, monitor TC lockup and slip RPM to determine if your specific application is fully locking the TC - or if there is excessive slip occurring.

Step 1 - make certain the speedometer cable drive has been properly calibrated for your gear and tire combination. GM cable drive speedometers require the cable to rotate 1000 times per mile. This calibration is achieved by ratio of the number of teeth on the speedometer drive gear (on the transmission output shaft or transfer case shaft), to the number of teeth on the speedometer driven gear (typically mounted to the transmission tailstock or to the transfer case).

Step 2 - setup the parameters in the PCM software as pictured below. After entering these values, the PCM will accurately interpret the signal from an 8K PPM VSS pulse generator (as long as the speedometer cable is rotating at 1000 PPM). After these changes, you CANNOT use the software to automatically scale the transmission shift speeds - you must now do this MANUALLY - table by table.

Attachment 95043

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I'll give this a shot next. Thanks for the reply!

Quote:

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Originally Posted by BrandonHall10

Hadn't even thought of contacting them. Just sent an email to their support desk. Thanks!



I'll give this a shot next. Thanks for the reply!

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A bit of an old thread, but I have a 6.0L with a 4L80E and an NP208 with the 8k pulse generator. My PCM keeps thinking the transmission is slipping and tripping 0730 fault code. Did you ever figure out your issue? Been trying to figure this out for months on my rig...

I have done something similar once before. I can?t remember which sensor I used, whether it was a DD, intellitronix or some combination of oem parts. But I do remember calibrating the speedo gears as close as possible and then playing with hptuners for like a week. When I get home, I can upload the tune of that would be helpful. However, I was using a gen 4 electrical/computer system

Quote:

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Originally Posted by SilverBullet6.0

When I get home, I can upload the tune of that would be helpful. However, I was using a gen 4 electrical/computer system

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Sorry. Just now getting back into this after a long hiatus. Yes please share your tune file. Maybe I could glean something from doing a compare.

Are you trying to fix a speedo problem? Or is it a transmission problem?

I'm only replying to this to help someone else in the future as I came across this when I realized I was having this same issue after a test drive. Maybe it was just me, but what fixed my issue with the speedo being off was changing the Sensor VVS Pulses Per Mile to 128,000, which is what my Dakota sensor was set to output (128)....BOOM calibration on dash showed 60mph like it was supposed to during test.

Solved. Updated original post.

Quote:

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Originally Posted by pilotXC

A bit of an old thread, but I have a 6.0L with a 4L80E and an NP208 with the 8k pulse generator. My PCM keeps thinking the transmission is slipping and tripping 0730 fault code. Did you ever figure out your issue? Been trying to figure this out for months on my rig...

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Has anyone figured this out? I have the same issue and am new to hptuners just got my 6.0 4l80 swap going in my blazer using the Dakota 8kvss and have the 0730 code also

I know this is an old post, but sir.....you are a godsend. A lot of DD VSS information out there is sketchy at best. I tripped over your post, followed your math to the letter......and it worked perfectly the first time out. GPS on my phone was in lockstep with the VSS signal. Because of the angle the VSS sits at coming off the SYE in my Jeep I can't reconnect the speedo cable until I get a 90 degree adaptor, but my OBD gauge shows speed so it's no big deal. Idle issues, DFCO and the exhaust popping on decel issues are all fixed. THANK YOU AGAIN!!! :D

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Attachment 137603

87 swap with 2006 5.3/4l60 but using 87 NP208 with mechanical speedo brought me here for info.

using Tuner Pro / PCM hammer info:

installed Dakota Digital SEN-01-4160 Pass-Through Speed Pulse Adapter from this thread i found in my research to keep dash mech speedo, and also supply VSS to 4l60e.

i assume the input fields referenced in original post above would make sense to someone fluent in HP turners (i have no experience)
using free tuner pro / PCM hammer (sorry HPT im cheap) i have the following to add that one more alternate calculation was needed (found in tuner pro notes / details for field) for TOS(transmission output speed) H0104.

above math to determine Trans revolutions per mile above makes sense but its not what tuner pro wants for Trans output speed, not sure if its a units thing or lost in translation or?

what i had to do in tuner pro:
change and input new value for H0101 VSS Pulses per mile to 8000 (or use above math to get your actual number close to 8000 (not the 9x,xxx typical oe, with inputs of tire size/gear ratio)
keep H0102 Vehical speed sensor pulses per rev to 40 (typ for autos?)
****calculate and input new H0104 Transmission out put speed by =H0101/H0102 *****

My numbers i left were
H0101 8000
H0102 40
H0104 200


shift points seemed fine and dash mechanical spedo was of course unchanged, data log on scanner showed GPS speed within 10% but more importantly now my TOS H0104 was also correctly supplying info for proper shift points now enabling shifts.



reason why im replying to this thread is because i spent lots of frustration coming to this solution. learned that the trans uses transmission output shaft TOS to calculate shift speed points, and doesn't use whats reported as vehicle speed in a scan tool, two separate numbers. it just didn't agree it was going fast enough to shift and therefore no codes or other indications of problems.

cheers carry on.

so update, still having issues. with a hard accell it goes 1-N for a second than locks in 2nd with coded P0502.

cant figure out whats going on but since donar was fine, it has to be VSS related with the 8k sensor.

any tuner pro help or experience with this Dakota Digital SEN-01-4160 appreciated.

updat2x My numbers i have now thanks to re reading above posts from Jon s.

H0101 8000
H0102 10
H0104 800
now flat foot shifting great no codes.