xssive

iTrader: (123)

Ok, swapping in a th400 from an a4. DO I need a vss signla if I am flashing to a m6 bin? Will all my timing tables be whacked if I dont give the pcm a vss reference?

12secSS

iTrader: (30)

Yes, you still need a VSS signal to activate different timing tables, enable DFCO (if applicable), cruise control, etc ...

Now if it is a race car, you don't need it.

xssive

iTrader: (123)

Well its going to be a street car with some track time. DFCO is already disabled as is cruise. If I have a m6 bin, which timing tables will be screwed up without a vss?

HumpinSS

iTrader: (1)

it will never reference the HO or Lo octane timing tables it will only stay in the base spark in park or drive tables because the PCM never sees movement

horist

Also your speedometer won't work... not a good thing for a street car heh

xssive

iTrader: (123)

Ok, so where do I get the reluctorand parts for the th400 to make the vss work?

12secSS

iTrader: (30)

Check out the Automatic section here, there is a sticky at the top with the info.

For those lazy to check, here is my post with the info:
https://ls1tech.com/forums/showpost....8&postcount=18

xssive

iTrader: (123)

I got it figured out. I am going to use the 40 tooth reluctor / vss sensor from a 454 and put the appropriate vss pulse info in the m6 bin file. Should work perfect!

cablebandit

iTrader: (37)

be CAREFUL changing the VSS stuff. There is ONE line you cant change in HPtuners. It is a bug with GMs software. If you change it and flash...pcm will be dead. I did this same th-400 swap...changed a vss line and boom dead pcm. Hptuners got the file and discovered the bug. Here is my email from Chris at HPtuners:

Hi Jerry,

I have located the problem and it is a bug in GMs PCM software

For some reason you have changed the VSS Output Pulses/Mile value from 4000 to 128, this is the issue.

I will have to disable this parameter in future versions as it seems any change to it causes a problem for the PCM hardware. Unfortunately even GM's own software allows you to make this change

Also unfortunately, the only way to recover your existing PCM is to have the flash chip desoldered and reflashed with a good calibration.

Chris...


So dont change that line. I used my a4 file...started the car and just deleted all the a4 codes that popped up. I also used a front wheel speed sensor for my vss signal. It was very easy to do...very easy but you lose abs which i had already deleted.

xssive

iTrader: (123)

Yeah the pulses per mile output will not change for any transmission swap or gear swap ever! Good reminder though. You are going to be changing 3 values in the vss table : vss pulse/mile, vsspule/rev and trans revs/mile.

Best way to do it is to get a stock a4 bin file, load in your tire and gear ratio, and have it calculate the correct vss values since the a4 already uses 40 tooth reluctor. THen copy those over to your m6 bin and you are set.

SATAN

iTrader: (2)

HumpinSS - "it will never reference the HO or Lo octane timing tables it will only stay in the base spark in park or drive tables because the PCM never sees movement"

I understand that this is a very old post, but that's what happens when you use the search feature like you are supposed to.

My car is running a powerglide from Transmission Specialties. It has no VSS or any kind of cable going to it for the speedometer. That's right, my race car has no speedometer.

So that means that the ONLY spark table I can tune would be the "base spark" table, correct? I have no problem with this, so long as it will work and I can still tune spark for 20psi and 7,000rpm (or whatever).

The only problem I can see is that on HPT, I have "Idle spark advance" Then I have two tables. One for "In park", and one for "In drive". Now on both of those tables, the rpm's only go up to 4,800rpm. That is where I see the problem.

Anyone got any ideas on that? Oh, and with no VSS of any kind, which one will it the PCM be using, In park, or In Drive?

MontecarloDrag

iTrader: (3)

I have tuned a few swap cars with Th350 and they used low/high octane tables with no Vss
I changed the idle spark tables to 20 degrees for the whole table, and did a datalog. I saw spark advance values from high octane table.