Looking to set a low vss value...will it work?

[3.1EyeCandy]

I'm working on putting a 2001 LS1 (Camaro) into a 1987 Pontiac Trans Am. I've gotten all of the mechanical issues sorted out for using my freshly rebuilt 700r4 with the engine - now I'm looking for solutions to the vss.

This trans puts out a 4 pulse signal (4000 ppm) - compared to the 40 pulse signal on a comparable 4L60e for the LS1. I've done alot of reading on this (https://shell7.tdl.com/~jags/V8-chapters/V8-tpi-Speed-Sensors.pdf is good) and searched/asked on ls1tech and it's come down to this:

It should be tuneable - guys recommended HPTuners as it will go that low for the vss pulse and say that they don't know about EFILive (older versions stopped at 10 and they don't know about newer versions). The shop I'm wanting to have the car initially tuned at uses EFILive....so is this going to work? Or do I need to find another shop?

[TAQuickness]

Welcome to the forum 3.1EyeCandy. Looks like the range for {H0102} Vehicle Speed Sensor Pulses per Revolution is 10-50 Pulses/Rev. I've emailed tech support for verification.

[Blacky]

The 10-50 limit is just an "safety" limit that EFILive places on the calibrations. We can easily expand those limits. The one caveat is that setting it to zero can cause the PCM to lock up. So I guess if we lowered the lower limit to 1, then you could set it to 4.

We will investigate changing the limits in the next software update.

Regards
Paul

[ChipsByAl]

I am not sure if you will be able to get the VSS signal correct with your current setup. I would recommend for a 1987 Trans Am to install the 40 tooth reluctor onto your 700R4 output shaft and corresponding vss sensor. Connect the sensor to your PCM as per factory 2001. Then you can use the PCM's internal buffer to send out a calibrated 4k ppm signal to your cluster, cruise control or whatever. If that is too high (4k), you can cheat and adjust the signal out as necessary. If you ever change gears or tire size, the adjustment in EFI_Live would get you right in one flash.
Al

[joecar]

+1... I agree with Al, swap in the 40x reluctor.

[3.1EyeCandy]

That is an option. Anybody have a good source for a definite 40 tooth reluctor for a 700r4? Searching for a reluctor for a 700r4 doesn't seem to yield the tooth count - and getting what I already have doesn't solve the problem.

If all else fails, I suppose a setup like what JagsThatRun makes (external reluctor mounted on the rear differential) would work. I was just hoping this is something that could be accounted for in the tune.

[ChipsByAl]

Just get a reluctor for a 2001 Trans Am. You can likely use a tailshaft from a 1996-7 camaro/firebird transmission. Do you have the 4L60-E or the 700R4 transmission (with the TV cable)? If you have the electric shift, the sensor and reluctor is already there.
Al

[3.1EyeCandy]

700r4 with the TV cable.

I talked to the shop with EFILive I was hoping to have do the tune and they said that they believe there's an update that would allow tuning for this VSS pulse signal. I'll investigate the newer 4L60 tailshift idea. Although, if tuning would avoid this - I'd like to avoid this.

Thanks for the help guys. It is my hope that there will be an update to EFILive before the time I have to go and buy more parts to modify this transmission.

~Jon

[GMPX]

I can test a PCM here with it set to 4, but I tend to think you would be much better off using the 40x reluctor. The problem I can see with the 4x is the resolution of your speed signal is greatly reduced, however, the flip side of that is that you are using a 700R4 so the speed sensor accuracy is not as much of a concern.

Let me see if the PCM locks up with the value set to 4.

Cheers,
Ross

[3.1EyeCandy]

Thanks GMPX! I've never used EFILive before and so am not familiar with what the labels are on each value. From the reading of that PDF above it would seem that my 700r4 outputs 4000 pulses per mile, compared to about 82,000 pulses per mile for a vehicle with the 40x, 2.73 gears, and 27 inch tires. Quite a significant difference!

The reduced resolution would definitely be an issue with say ABS, or electronic control of the transmission...but seeing as I have neither of those it really isn't a concern at all.

Thanks for all of your help. This forum has been incredible and this is only post #4.

[3.1EyeCandy]

So how'd the testing go? Should I go ahead and pickup the externally mounted vss setup?

[kbracing96]

I think Advanced Adapters makes a 40 tooth reluctor that just clamps onto the out put shaft. I used one on the 5.3/4l60 I put in my dads 72 Chevy 4x4 pickup.

[3.1EyeCandy]

It's been quite some time, but I was just wanting to check if the vss setting had been allowed to go lower. The car is at the shop now.

I had bought and installed the jags-that-run kit that mounts on the rear differential...but with a new adjustable torque arm it had to be removed due to lack of clearance.

The shop is going to try and use the signal from the 700r4 (4000 ppm)...

[LS-SWAPPER]

This is extremely old, but I was wondering if any more discussion on lowering the number had occurred. If I'm not mistaken some of the aftermarket sensors for adapting to an older style cable drive use 8 or 4 pulse per revolution.

[Brads_rs]

I would also like to know if anyone has had any luck with running a 4000 pulse vss by lowering the numbers.

[LS-SWAPPER]

While we are on the subject, I recently used a Dakota Digital 8000ppm cable to electronic converter on an LQ4 swap with a non elect transmission. First off I have a problem with all these parts being labeled in PPM, how does dakota digital know that my trans output needs to turn 8000 times to move me a mile??? Am I in a monster truck with 52" tires or a low rider with 20" tall tires? 4.88:1 gears or 2.73:1??? Most people online assume that 8000ppm roughly equals 8PPR or pulse per revolution of the sensor (someone correct me if I'm wrong there). But depending on what the plastic gears are in the trans that are tuning the sensor, I'm not really sure how may PPRev it is actually making. So I called Dakota Digital and asked them, how many PPR their sensor generated. I asked it in terms of "how many pulses per 360 degrees of your SENSOR turning" so in other words forget about whatever my internal plastic gears are doing. I planned to count the plastic teeth and calculate back from there. Their answer was "approximately 8 pulses per revolution of the sensor...", how can it be approximately??? I got frustrated, told them thanks, and polity ended the call.

So what I did on the vehicle was go to the speedo calculator in the Tune program and set up everything I could, tire size, rear end ratio, etc. I put 10 in the PPR field just because it was the lowest number I could use. Then I got my gps and used the speedo correction calculator to put in the actual and desired speeds. After applying the correction everything seems to be accurate. I don't know if I have confused the computer any way, but so far so good. Just thought I would share.