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-chap...ed-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.