sillyiroc

I just finished my T56 swap today on my 89 Iroc 350 Tpi. I took it for a ride and I noticed that when I slow to a stop with the clutch in It stalls. The car has always idled a little low like 550-600 rpm but when it was an auto it never stalled. should I adjust the IAC.

kevinc

Wow, that was quick!! I suspect you're not getting the right VSS input to the ECM...recheck which output you're using from the Dakota Digital box, and that the DIP switches are set right.

I had it configured both output pin and DIP settings for 2000 pulse/mile output...optical VSS. Yours being a newer model it may be set up for magnetic VSS, in which case it wants 4000 pulse/mile. I'd say reconfigure it for 4000 and retest.

The config sheet for the Dakota box can be found here:

http://www.dakotadigital.com/manuals/SGI-5A.PDF

I believe you want "Application 3" in the document, verify the DIP switches are set accordingly. I would have been using the OUT 5 pin to get my 2000 pulse/mile output, you'd want to move your VSS output to ECM wire to OUT 4 to get 4000 pulses/mile.

TKOPerformance

I'm hearing that this could be a VSS related problem. You aren't alone. I had the exact same problem after my T56 swap. My solution was to adjust the idle set screw in about 1.5 turns until the symptoms went away. I'm told that this is a crutch though, and my real problem could be VSS related. TPIS recommended that I adjust the IAC steps with the throttle screw, which is why that's what I did. I've been running my car for over a year like that, and haven't had any problems.

My idle is still a bit unstable, but I'm running an aluminum flywheel.

kevinc

The only other thing that comes to mind is the PROM. If you're still running your old automatic trans PROM, the ECM thinks you're in Park/Neutral.

Try the VSS thing first and report back.

TKOPerformance

Unless you already have the Dakota buffer box I'd try to adjust the IAC first. Why? Simple, it's free.

You may also get a trans related trouble code, but it won't be VSS related. It'll have to do with the overdrive lockup. I had a custom PROM made to account for this.

kevinc

He's got a Dakota Dig box already, compliments of the wonderful guy who sold him the T56 swap package.

You want at least semi-accurate VSS data into the ECM, it uses it for fan management (no need spinning the fans if you're driving at highway speeds) and do IAC management beyond just static idle RPM control.

TKOPerformance

I'm guessing he bought the package from you. Then he should be all set.

Fan management isn't a problem for me. I took it out of the ECM's hands quite some time ago. I run a Painless wiring 185 on/175 off relay system that has been modified to run all the time with the AC on to avoid damaging the system. I used a second relay and a couple of diodes to prevent feedback. The AC relay just controls the ground, since the stock Painless system uses a thermistor to create a ground signal, which is what turns on the fan. Then the diodes buffer everything so that when the fan activates while the AC system is already running the fan there is no feedback.

I eventually want to hook up the VSS setup in my car, but I can't afford the Dakota box now, and have other things I'd rather fix on the car first. I know it's semi-important, but it isn't absolutely necessary.

sillyiroc

sorry it took so long to reply, I have been out of town. I don't even have the dakota digital box hooked up yet. I just was so excited to drive it i didnt think it would be a problem but I guess it is. The thing is I dont quiet understand how to hook it up. I havn't even realy tried yet. I dont even know where it goes. hey kevin Thanks for the great stuff I had it all swaped In a day and it works great! Some info would be great.

kevinc

Cool, glad you like it (and simultaneously hate I couldn't use that T56 w/ my LS1).

Check my other post above for a link to the Dakota document, look under Application 3 on that sheet.

sillyiroc

I think I have a better understanding of how to hook it up but were do I mount it?

kevinc

I had it zip-tied to the steel brace in the shifter console, but that location suited my wiring setup. The car was rigged for cable driven VSS, so I had to build a harness for both the reverse lights and VSS. I used the old shifter cable hole and grommet to run them thru the floorpan.

sillyiroc

Ok I will try and hook it up. thanks for the help.

jmd

iTrader: (4)

Unhook the park/neutral wiring ( I believe in a third gen it's in the shifter? ) so the circuit is open and in "drive" all the time. This is how a T5 car is setup.

Get your VSS working. Stalling & other "noticable" things can and will occur without it. w/ the Dak box, you should have what you need.

Also, go for the 6 speed Vette .bin as a starting point ( manual trans. & set for 5.7L ) and that should do it.

sillyiroc

should i unhook the plug or just those wires.

mike88form350

I did the auto to t-56 swap with out a dakota box. as far as i know 90-92 cars are the only cars that use magnetic VSS speedos.

i just used a five speed speedo sender and put my 3.27 gear out of the automatic in it, works perfect reads dead on. that worked great on my tremec i guess it might be different on a borg w.

kaitlin

iTrader: (5)

i know this thread is old but im having same problem and need it repaired afaik the t56 vss is working because i have a speedo reading just need to know whoelse has encountered this problem and what they did to fix it