T56 Swap into 93...VSS Problems...

I was doing a search on the board about the different VSS on GM cars and it seems my 93 Z28 VSS is different than the one on the 95Z T56 I put into my car.

Does anyone know a good way to correct this? Because my computer says I'm doing 255 MPH! My speedo is pegged all the time. Thanks.

The 93 intrument clusters are totally different from the later models! IIRC someone once told me if you put the guages from a 93 in a 94 the needles would got the wrong way, so maybe they were right :) You should be able to put a 93 VSS in it and be ok. Remember they switched the computer in 94 ;) you might be able to reprogram it but with it being a 93 you'd be better off to just change the VSS.

Ok I just paid attention to the subject are you swapping out an auto for the 6 speed? because the auto use a different set of factors than the 6 speed it throws it way off! The auto vss does like 40 ppm where as the manual vss is like 17 ppm. In which case you are going to need a prom for a 6 speed car.

I'm not sure if the first part really applies to you or not now :) I'd check the part# on the VSS for 93 vs. 95 and see if they are the same.

Good Luck
Richard

Hey man I checked the part #'s for you. The 95 and 93 VSS are the same part # for the 6 speed so that's not and issue for ya ;) It's got to be the PROM!

I just got my chip reprogramed for the T56. Things are running great.
Jason

A BIG HUH? I flashed the prom myself to make it for a 6 speed. The only thing to change is the one check box that declares it a 6 speed or automatic. Did I miss something else???

Thanks.

I'm used to the 94 Flash parameters in TC. What are you using to do your editing? TC has a feature that will compute and then insert the numbers in the proper places for ya.

Well maybe you don;t know, but 93s are different than 94s when tuning. Alot different. There is no "Tools" Section for 93s in Tuner Cat, no Speedometer aduster. I think we 93 owners have a "box" or something to replace..?

There are four different things in the ECM Constants table of the 94 program.
Speedometer Scaler
Speedometer Scaler, Fraction
Speedometer Scaler, (Scan Tool)
Speed Pulses Per Driveshaft Reolution


Do you have these within the 93 program?
If you have these in your tables then shoot me your tire size and rear gear ratio and I'll use the calc tool in the 94 program to get the values for you.

You can do it with the tune, no box is need. i just did it on mine....like i said in the other thread, its not like a 94-97 conversion, the speedo will read 17/40 of actual without the 6spd bin file. not the case in the 93's...i'd send ya my bin file, but you wouldnt run.

So what would I change in Tunercat? I don't see anything that would make a difference... Thanks.

Ok heres the dealio, there are 2 values that could be edited in TunerCAT for the 93s. 1 is "Road Speed Constant" and the other is "Instrument Panel VSS Pulse divisor"

The facts I know are that my old VSS was 40 pulses per revolution, and the new one is 17 ppr... that's a 42.5% decrease is pulses.

Maybe change the "Instrument Panel VSS Pulse divisor" value? Its current value is 0, so how would I make a -42.5% difference??? Or am I thinking about this all wrong...

Any ideas? Thanks.

Up, up and away!

TTT, racking up fake miles! HELP!

Stupid question, what does the TC help files say about it?

Secondly, I know the systems are different, but without reprogramming my conversion, my speedo read UNDER value....

Jonota

TC says nothing. Its help system on the DEF files are useless.

Yeah, your VSS in your 95 4L60E was different than the one in my 4L60, different sesnors in our automatics....

Anyone?

We did the same thing in my buddies 93...and for the life of me I can't remember how we fixed it.
I know it was in the chip though...let me look in my old files and I'll see if I can remember what I did.

Thanks, I would greatly appreciate it :bow: :bow: :bow:

send me the file your attempting to use, I want to see something...