ATTN: T56 swappers...VSS code 24
 

So I did the T56 swap and I tuned out my automatic transmission but I'm still throwing a code for VSS. After further research I see that not only does the VSS work with the trans but also the IAC. My idle sucks, is there anyway to bypass the VSS or do I need to pick up one of those Dakota Digital SGI boxes?

no way you can find out how the IAC is integrated with the vss and wire accordingly?

I probably could but I heard the VSS wires from the T56 and the 700R4 give off different signals so it wouldn't read correctly.

I asked you this before you started!!! It's related because the ECM is confused on how fast you are going now!

I do believe the later VSSs send a different signal (IIRC # of pulses changes), although I'd have to go research the detail, so I'll leave that to you. :)

http://www.jagsthatrun.com/V8-chapte...ed-Sensors.pdf

http://www.skulte.com/T56.html
The f-body T56 has a 17 pulse per driveshaft revolution VSS signal generator in the tailshaft. This has to get converted to a 4000 (or 2000) pulse per mile signal for your VSS buffer input. The easiest way is to purchase the Dakota Digital SGI-5 signal recalibration box to do this. This is just spliced in between the transmission and chassis wiring. I also put together an Excel spreadsheet to calculate the VSS divisor ratio if you are so inclined.


Really? Argh. Stop posting in tech.

Is this for TPI? If so your car will never get out of cell 4 without the VSS, ask me how I know.....
TPI HAS to have VSS to work properly

i was asking for my own references for the fact that i was a little iffy on how the vss operated. christ. cant ask a question because mr bonzo is gonna have a breakdown and cry about it.


fyi your explanation was exactly the answer to the question i wanted to know

:lol: Like mentioned above, I didn't realize the VSS controlled other things other than the tq converter lockup. Also because my car has a mechanical speedometer. Now I understand, guess I gotta spend another $100 or so...ugh lol

And Scooter, the car is TPI

Just get a new tune. The prom you have will never work correctly with your swap. Even if you convert the signal. You need to get a reprogram. The iac and other things are programmed differenlty to work with manual vs auto. Check out the diy prom section on thirdgen.org.

i thin it was a 5 speed before he put it in fyi

No.

His point was valid. He went from an auto to manual...

Everywhere I read different info pops up for this swap lol I just made a post over there so we'll see what's up. carburetors keep sounding better and better...




Nasty, I went from Auto to manual

Don't take the easy way out! Man up! :mrgreen:

:lol: The more I do to the car the better it sounds


So after more research I'm finding that the pre-90 camaros without the electric speedometer etc have a buffer box which takes the signal from the IAC to the ECM. The Dakota box basically bypasses this buffer box feeding the correct signal to the ECM. When I convert to an electric speedometer it will be read from this box. Changing just the Flag/Switch in TunerPro from Auto to manaul should bypass most of the issues, the only thing that might still remain is highway mode etc. which is just relative to gas mileage. Right now in 6th gear doing about 80 I'm at 1600 rpm's so how much gas mileage can I be losing :mrgreen:

No you are still going to have problems with your car not learning properly. As Fast92RS states you need a new tune. I suggest buying a prom for a manual car and go from there.

What I can't find a clear answer on is why, what exactly are the differences? A chip for a manual car is more work because that involves changing fuel tables and a few other things I've read whereas this is just IAC. And again, I'm not going to pay someone to reprogram the chip when I have everything I need to do it myself; the problem is I don't know what to change.

Well you are in a bit of a pickle there then. You really NEED to have the manual chip or your car wont run at its full potential. I dont know the differences because I dont look into code but I know it doesnt really "work" right after a conversion without the proper chip, or programming. I think the car wont come out of cell 4 because of this.
If you have and AutoProm and chip adapter then you just need to burn a new one. You can just copy the tables and paste them into the new burn.

I guess what I'm having trouble understanding is that if the car works with the automatic VSS feeding the ECM then in turn the IAC etc and I switch transmissions and basically replace the stock buffer box with the Dakota box converting the new VSS signal to the ECM, what has changed? I'm guessing the VSS signal and pulses are relative to what gear I'm in based on revolutions and since the 700R4 isn't electric then what is the difference there also? If my only option is to have someone do it then fine but I want to at least know what needs to be done and why before I jump into it or just give up.

The automatic setup might be using the torque converter lockup signal for something that the manual doesn't need when doing fuel table calculations. I've never looked into the programming deep enough to understand what's really going on in the PCM.

Lets just say this: if you leave the auto chip in the car with the manual trans you are going to throw codes. I did it for a little while and had some problems.....
You have the stuff to fix yourself, I told you what to do... and Fast too. Just re-burn the chip with the appropriate .BIN and then copy your fuel and spark tables over :nod:
Why are you still debating the issue?

First off TPI cars didnt have a buffer box. Only TBI cars and firebirds with the electic speedo.

You need the SGI box to feed the ECM a VSS signal since you dont have a "working" mechanical speedo anymore. Since the VSS is on the back of the instrument cluster. I do beleieve that Jagsthatrun.com has a T56 tail section with a mechanical speedo cable hook up for it that will allow you the use of you stock setup. The only downfall to this is that tail section is about 300 dollars

Scooter BLM cell stuff is for 90-92 cars.

The reason why you need a manual bin is on how the ECM controls the IAC in a/dcell and idle. Start with the ARAP.bin (AYPY.bin is the same as the arap but for the auto.. I could be backwards as it has been a few years since I've mess with the 165 ecm).

Use the compare feature in tunerpro to see what changes were made to the chip that you had done at JS. (or swing by when I get back from Hawaii and I'll be more than happy to set ya up!) Do the injector constant, fan temps and the usual **** for what you have for your car.

Re do the min idle/TPS settings on the throttle body after you have the manual bin loaded. Rember auto cars can idle lower due to the greater rotational mass hanging off the back of the crank. I had that problem when I had my old 89 iroc.

The VSS does not directly control the IAC at all. CTS, TPS, LV8 and more so VSS controls it. It takes all of the inputs from the sensors to decide on what to do with the IAC. Weither you are in acell and it will be using the IAC for the throttle follower feature( when you let off the gas and the engine drops right back to the idle setting instead it slows the drop). etc...

VSS signal is constant. X amount of pluses per revolution of the DS. The faster the ECM is getting them, the faster you are going. Yes it is that friggin simple.


I think that about covers it.

That's what I have been trying to find...thank you!

I never messed with the 165 stuff, thanks

Thats some good info. Ive been olny tuning my car to work with my new set up. I have speed density TPI set up and its pretty easy to tune.

Me too and I have no idea what the hell I am doing. I tried a few times, got frustrated and havent touched it since. I also got pissed at it because people on TGO.org dont really help when you ask questions