LY6/L92 into my firebird with m12 t56 e38 ecu. VSS Output problems

[liveaxlels1]

Let me give you guys some background:

I put a LY6 (smaller L92) into my Firebird with a m12 t56 out of a 2004 GTO. The problem is that the speedo will not display even remotely correctly. I have tach working, oil pressure and level working, coolant temperature and everything. This is all on factory electronics with the e38 ecu.

When I'm going about 20mph the speedo will peg. When I'm going 5mph the speedo will think im going 70; I'm off by a wide margin.

I've tried setting everything to (what I believe) are the correct values. Ive looked at the stock tune from a 2004 GTO and copied the VSS input pulses and inputted my 3.42 gear ratio with my correct tire size (24.92 for 17" tires with 315/35/17 tires). I've tried setting insanely high values for everything (6.1 gear ratio, 40000 pulse input, smaller tires etc) and still cannot get the thing to read correctly on the cluster speedo. The speedo in HPTuners reads pegged to 158mph when trying to log and I deleted the .os file. I've tried adjusting the wheel speed pulse ouput average but that has no effect whatsoever. It seems that everything I try (either setting correct values or incorrect ones) does not work. The VSS is wired into the ecu correctly and the output is coming from the only speed sensor output I can see on the e38 ecu pinout for my vehicle. Everything is wired correctly... I've seen other posts about the 2004 GTO vss being an oddball, but does anyone have any ideas??

I'm using the 2.23 beta version... could this be a problem with the beta software not setting values correctly or something? Not to blame the software, it's an absolutely incredible product, but I just want to find some answers. If anyone has ideas, I'd be most appreciative!

edit: also, I find it strange that there is no specific "vss output pulses per mile" section in the speedo area for my e38 but on other vehicles there is... is this by design? Also, does the e38 possibly have a vss aux output somewhere? If so, where?

[LSX378]

Let me give you guys some background:

I put a LY6 (smaller L92) into my Firebird with a m12 t56 out of a 2004 GTO. The problem is that the speedo will not display even remotely correctly. I have tach working, oil pressure and level working, coolant temperature and everything. This is all on factory electronics with the e38 ecu.

When I'm going about 20mph the speedo will peg. When I'm going 5mph the speedo will think im going 70; I'm off by a wide margin.

I've tried setting everything to (what I believe) are the correct values. Ive looked at the stock tune from a 2004 GTO and copied the VSS input pulses and inputted my 3.42 gear ratio with my correct tire size (24.92 for 17" tires with 315/35/17 tires). I've tried setting insanely high values for everything (6.1 gear ratio, 40000 pulse input, smaller tires etc) and still cannot get the thing to read correctly on the cluster speedo. The speedo in HPTuners reads pegged to 158mph when trying to log and I deleted the .os file. I've tried adjusting the wheel speed pulse ouput average but that has no effect whatsoever. It seems that everything I try (either setting correct values or incorrect ones) does not work. The VSS is wired into the ecu correctly and the output is coming from the only speed sensor output I can see on the e38 ecu pinout for my vehicle. Everything is wired correctly... I've seen other posts about the 2004 GTO vss being an oddball, but does anyone have any ideas??

I'm using the 2.23 beta version... could this be a problem with the beta software not setting values correctly or something? Not to blame the software, it's an absolutely incredible product, but I just want to find some answers. If anyone has ideas, I'd be most appreciative!

edit: also, I find it strange that there is no specific "vss output pulses per mile" section in the speedo area for my e38 but on other vehicles there is... is this by design? Also, does the e38 possibly have a vss aux output somewhere? If so, where?

What E38 tune are you running? 2.23 works fine here for setting E38 speed settings. Mostly.

[liveaxlels1]

Just stock tune from a 2007 Chevy Silverado 3500 HD pickup.. 6L90 auto tranny was on it, stock, however it's now a m12 T56 from a 2004 GTO. How would tune affect speedo settings? Am I missing something?

[LSX378]

Just stock tune from a 2007 Chevy Silverado 3500 HD pickup.. 6L90 auto tranny was on it, stock, however it's now a m12 T56 from a 2004 GTO. How would tune affect speedo settings? Am I missing something?

The auto tune gets its speed info on the CAN. Is your VSS output wired to the VSS pins on the E38?

[liveaxlels1]

I've got them wired to pins 71 and 72 on connector x1 on the ecu. 71 is the vss high signal; 72 is the vss low signal. Pin 57 is what I am using for vss output (yellow/black wire). Is there perhaps another connector on the ECU that has the 4000ppm speed output?

[LSX378]

I've got them wired to pins 71 and 72 on connector x1 on the ecu. 71 is the vss high signal; 72 is the vss low signal. Pin 57 is what I am using for vss output (yellow/black wire). Is there perhaps another connector on the ECU that has the 4000ppm speed output?

OK. Your pinning is generically right, but your ECM if it is a typical A6 OS is most likely not expecting VSS on 71/72.

In HPT take a look at Speedometer > Vehicle Speed Output. If it is set to "serial", try "REPTos".

[liveaxlels1]

I've tried that lol. I've set wheel speed output to disabled (and enabled) as well as changed Vehicle Speed Output to RepTOS; no go. If I disable the wheel speed output and enable vehicle speed output (RepTOS) then the tach does not move at all under any configuration settings. If I enable both vehicle and wheel speed signals, it pegs and the calibration is way off under almost any configuration setting.

One thing I notice under the wheel speed output setting is that it's a 128k ppm output..... this would explain why, under any configuration setting, the speedometer is pegging and way off calibration. My cluster is a 4000ppm cluster.. I dont think theres any amount of calibration that will take a 128k ppm and convert it to 4k ppm (except with a dakota digital box which I'm trying as hard as I can to not use one of those things).

[LSX378]

I've tried that lol. I've set wheel speed output to disabled (and enabled) as well as changed Vehicle Speed Output to RepTOS; no go. If I disable the wheel speed output and enable vehicle speed output (RepTOS) then the tach does not move at all under any configuration settings. If I enable both vehicle and wheel speed signals, it pegs and the calibration is way off under almost any configuration setting.

One thing I notice under the wheel speed output setting is that it's a 128k ppm output..... this would explain why, under any configuration setting, the speedometer is pegging and way off calibration. My cluster is a 4000ppm cluster.. I dont think theres any amount of calibration that will take a 128k ppm and convert it to 4k ppm (except with a dakota digital box which I'm trying as hard as I can to not use one of those things).

Ok you tried all that too. Good .

"........then the tach does not move at all....." ? Assume you mean the speedo ?

And assuming you have all your other speedo parameters correct, like VSS ppr, wheel rpm, which it sounds like you have, maybe your only choice is to switch to a manual tune.

Have had customers come in with other parties claiming auto tunes will work fine, but they often dont. Reptos works fine with a speedo feed from an A4/A6 but that is a single wire TCM formatted signal to VSS hi with the other side grounded. Also had trouble with the HPT PPM number as well. Mostly too high and speedo reads low. Depends on the OS. Tracking GM's changes on these things must be a real headache for them.

What is the OS number?

[liveaxlels1]

not sure on the OS number - I'll have to get that to you... I do need to have the motor tuned for sure, but not sure who to take it to for that. Tach works fine (sorry for the typo on that). Where do I find the OS number? Also, I read a post somewhere about multiple RepTOS pins... one guy said on his variant of the e38 there was an additional reptos signal on pin 1 of the x1 plug; could this be the 4k ppm output if enabled in HP Tuners? I'm certainly going to try it.

As far as a manual tune... what all does that get me? Can I just take HPTuners up to a professional tuner and have him run it up on a dyno? I'm north of Atlanta, GA (about 20 min. north) so I'm not sure who to go to for a good dyno tune.

[LSX378]

not sure on the OS number - I'll have to get that to you... I do need to have the motor tuned for sure, but not sure who to take it to for that. Tach works fine (sorry for the typo on that). Where do I find the OS number? Also, I read a post somewhere about multiple RepTOS pins... one guy said on his variant of the e38 there was an additional reptos signal on pin 1 of the x1 plug; could this be the 4k ppm output if enabled in HP Tuners? I'm certainly going to try it.

As far as a manual tune... what all does that get me? Can I just take HPTuners up to a professional tuner and have him run it up on a dyno? I'm north of Atlanta, GA (about 20 min. north) so I'm not sure who to go to for a good dyno tune.

Edit > calibration & controller details get the OS and related info. Post your tune.

X1 pin 1 is normally the park-nuetral auto trans signal. though Gm changes these things around.

OS with manual oriented calibration gets you an ECM that IS looking for VSS across 71 and 72.

[liveaxlels1]

is a manual oriented calibration something that i can do on my own with hptuners? if so, how? are there any tutorials/write-ups?

[LSX378]

is a manual oriented calibration something that i can do on my own with hptuners? if so, how? are there any tutorials/write-ups?

If you can get a manual tune of the same type, yes HPT can do it but may charge you an additional credit or two.

There are some people on the forum who do "segment swaps" maybe they can swap in the right manual segments for you and avoid the credit charge. Not sure how HPT does this, but there are some out there that do this.

You should find them by searching. EC tune I think was one. But maybe it is limited to trans swaps.

[liveaxlels1]

ok, here's my .HPT file; let me know whta you guys think - im sure some of those values might be way off... have a look!

[LSX378]

ok, here's my .HPT file; let me know whta you guys think - im sure some of those values might be way off... have a look!

Well the good news is that you have a couple things to adjust...

VSS pulses need to be 17 (40 is A4), diff ratio is 1:1, that needs setting right. Or maybe you tried already.

The bad news is that there is no manual Silverado. Typically a manual tune shows the PPM for the VSS which can then be adjusted as necessary.

From memory 07 auto tunes dont like manual trans for some reason. 08's more tolerant.

[liveaxlels1]

well, the thing is... yes I've tried setting to what you're suggesting (3.42 ratio and 17 pulse per revolution) but that only results in the speedo pegging

I've played with that to no end and don't seem to have any clear notion as to what to do.

If I select the Vehicle Speed Output to RepTOS - it simply doesn't make any difference, that is, it doesn't do anything.

How could I go about modifying the PPM output? Can I re-configure segments of the installed e38 OS somehow? To, perhaps, enable the PPM output options? I would imagine that it's similar to any other hardware OS in that you have certain switches that turn things on or off for various configurations, A6/M6/A4 etc.

Also, surprise, the pin for the Reverse Lockout Solenoid does not work - is there anything that I can do about that?

I refuse to believe that there is nothing that I can do to fix this.... every other gauge works BUT the speedometer. Even the oil level sensor! haha.

edit: I also looked at the stock hpt file for a 2004 GTO M6... the VSS pulses per rev looks to be set at 40?? Strange...

[liveaxlels1]

Really all I need, at bare minimum, is the ability to control VSS output pulses per mile so that my cluster will play nice... From what I can tell, my ECU IS getting a VSS signal and passing something on to the cluster, but what the cluster is getting is waaaaaaaaaay off.

[LSX378]

well, the thing is... yes I've tried setting to what you're suggesting (3.42 ratio and 17 pulse per revolution) but that only results in the speedo pegging

I've played with that to no end and don't seem to have any clear notion as to what to do.

If I select the Vehicle Speed Output to RepTOS - it simply doesn't make any difference, that is, it doesn't do anything.

How could I go about modifying the PPM output? Can I re-configure segments of the installed e38 OS somehow? To, perhaps, enable the PPM output options? I would imagine that it's similar to any other hardware OS in that you have certain switches that turn things on or off for various configurations, A6/M6/A4 etc.

Also, surprise, the pin for the Reverse Lockout Solenoid does not work - is there anything that I can do about that?

I refuse to believe that there is nothing that I can do to fix this.... every other gauge works BUT the speedometer. Even the oil level sensor! haha.

edit: I also looked at the stock hpt file for a 2004 GTO M6... the VSS pulses per rev looks to be set at 40?? Strange...

How are your other guages connected to the ECM?

Yes there are "switches" that enable certain options (VSS source being one), though if they are not exposed in HPT, well, thats it.

If you know someone into electronics, maybe you can access an oscilloscope and confirm the waveform.

Or send your ECM to Chuck @ Corvettes of Westchester NY and they could flash a compatible manual OS into your ECM that shows the VSS PPM setting. No idea what they charge.

And yes the reverse lock out doesnt work because the ECM is setup to run an auto.

[liveaxlels1]

We have a 3-pin ECT sensor (ecu signal, cluster signal, ground), one-wire oil pressure sensor directly to the cluster, oil level sensor wired directly to cluster, tach signal comes off of the ECU tach output signal (which didn't actually have a pin to begin with, we had to recycle a pin from a different/unused pin on the ecu plug, that is, the signal was previously unused but the pin remains active??)

Could it be an electrical issue? Could the cluster be seeing the incorrect electrical values?

[LSX378]

We have a 3-pin ECT sensor (ecu signal, cluster signal, ground), one-wire oil pressure sensor directly to the cluster, oil level sensor wired directly to cluster, tach signal comes off of the ECU tach output signal (which didn't actually have a pin to begin with, we had to recycle a pin from a different/unused pin on the ecu plug, that is, the signal was previously unused but the pin remains active??)

Could it be an electrical issue? Could the cluster be seeing the incorrect electrical values?

Ok so you are getting only tacho and "speedo ?" directly from the ECM?

What year is your firebird?

[liveaxlels1]

1994 Firebird. Tacho works perfectly using a pull-up resistor.