OK I have done a search and I have read all the tech articles out there.
I have just put my T56 in and I am still alittle confusded if I need this or not. Some people have said you dont need it for later years and then some say it will run fine without it and some say I need it????

Can someone just give me a "yes you need it" or a "No you dont".Its not a problem to get it and hook it up if I do. Thanks Eric

 

You definately need it. The T56 puts out a much faster signal, so your speedo will read like 10X what your actual speed is.

 

http://www.eecis.udel.edu/~dzug/92z2...0-vss4T56.html

here is just one I found doing a quick search. I feel this is the best one

 

heres the deal:

the T56 VSS outputs somthing along the lines of 40,000 pulses per mile.(roughly, changes with gearing.)

the stock 3rdgen VSS puts out 4000 pulses per mile.


there are three things that use a VSS signal.

ECM
Cruise control
Speedo in later model cars. 90+camaros, i donno the firebird years. anyone with a electric speedo and not a cable, needs the VSS signal for the speedo.



so lets look at WHY each needs it.

ECM:
on autos, it needs it to know when to lock up.
it needs to know it for highway mode.
it needs to know it for emissions controls

so, if you have a manual trans, dont mind the gas milage change, and arnt emissions controlled, you dont need it for the ECM.

cruise:
kinda obvious, it needs to know the speed, to maintain the speed.

speedo:
it needs the signal or the cable spinning.




solutions:

for electric speedo cars, the dekota box is all you need. you convert the T56 signal to match the 3rdgen pulses per mile signal. everything operates like stock.

for mechanical speedo cars:
the VSS signal is generated behind the gauges, from the spinning cable.
the simplest solution for these cars is to get a box like the cableX. it spins a cable with a electric motor to match the T56s VSS.
of course, the spinning cable is like stock, so it makes the VSS signal behind the gauges like stock, and everything works like stock




in a nutshell:
elec speedo car: dekota digital box
cable speedo car: cableX box.

 

https://www.thirdgen.org/techbb2/sho...hreadid=262002

I have an idea. Quit posting multiple threads. Post in the same one until your question is answered.


It's good, but you can't get the speedo exact. Just pretty close. The Dakota will let you dial it in perfectly.



It's not anything per mile, it's 17 per driveshaft revolution on most T56s.


Not true. Let's not propogate the redneck / Street & Performance method of ECM inputs please.

Engine control is in need of VSS on a manual trans car. Ever drive one without a VSS? It stalls. (of course you could raise the idle entirely too high to avoid that, but you can also put swampers on a thirdgen to ford streams too.)

Where did you get the "Manual cars don't need VSS" information, and why are you repeating it? Obviously it's not from trial and error, so please share with us why the ThirdGen Enquirer is still published?

 

because, ive DONE it. twice. to two cars.

ive driven one of them every day for about 7 months before i pulled the motor.


you tell me.
what the hell does the ECM need to know the speed of the car for? what if you dont downshift to a stop?


it uses the MAP sensor, RPM and IAC to keep the engine idling at the set number and from stalling.

exactly like 100s of other various ECMs out there.



ive done it on two seperate cars without issue. furthermore, ive helped alot of other people online do it. the most common scenario being they dumped the T56 in, and dont have the converter box yet.
have you ever DONE it?

furthermore, the big problem people have, esp when they do this with a auto->T56 conversion, and what i suspect the source of YOUR myth is, is when people dont tell the computer its "in gear"
if you're running a auto ECM setup, and it thinks its in park/nutural, then it stalls. look at the T56 swap sticky for the wires, i dont recall off my head anymore.




hence the "changes with gearing" statement.(just because i put it in parenthesis, doesnt mean you shouldnt read it)

 

It can't use MAP as a reliable input to keep the engine idling because the MAP value will change when the throttle is moved. depending on throttle position. IAC is used, but it's not an input to the ECM for what you claim. RPM is the output they're controlling (with IAC,) not an input to control itself. Which leaves us with mph.

You shouldn't be angry because someone criticizes how your car happen(ed) to be setup. That's heavily counterproductive. You should try it both ways. I have.

Gee I dunno. I've had two T5's and a T56 in my car, it was CCC carbureted with a T5, then TPI with a T5 and I left the steering column park neutral switch in place & connected so I could experiment with the P/N switch, and VSS. And I've done T5 and T56 swaps in other cars besides my own, including using the Dakota Digital box in them. So yeah, let's just say I've been around the VSS block.


I know. I kept telling that to a truck owner on this forum from Oregon. He didn't believe me until he installed a VSS and undid the VSS-in-park situation.

A PM from someone else (with a third gen w/ T56) that I mentioned this to:

Thanks for all the help. I unhooked the park/neutral switch and installed the SGI-5 and the car runs and idles much better. Thanks again.


See above.

Right. Which is why it should be referred to as "per driveshaft revolution" and not "per mile" because it helps people who don't understand, understand by clarifying between the two types of VSS systems.

 

been running mine sans vss for quite awhile now.