I have the SGI 5 box hoked up in my 91z28 along with a t56. well we all know the deal with the SGI 5 box. anyway, after not getting the right output selected, my SES light came for a VSS.well, if it comes on while driving and I come to a stop, the engine will idle real low under 500 and stumble then die on me. if it doesnt stall, it just idles where it should be. if I use OUT 4 on the box then the speedo reads about 80mph while Im stopped but the idle is about 1100RPMs.the speedo reads as it should as soon as I move foward. is the computer raising the idle because it thinks I am doing 80 mph? what causes all this to happen? also my box IS hooked like the directions say.

 

Not that familiar with the box, but VSS controls operation of EGR. Your problem is typical of the EGR not closing when you come down to idle.

 

EGR? ya right, I have a Stealth Ram in my car. why doesnt the VSS light come on as soon as I start driving? it only comes on if I decelerate in gear. it goes away if I rev my engine high while accelerating.

 

Sounds to me like you have all the answers:hail:

 

I have had about the same experiences as you with my T56, Dakota box, and VSS. Every once and awhile my speedo would quit, throwing a VSS code and then upon deceleration or idling, it would slowly go down to 500rpms or so and then die. Now I'm having other problems trying to get it to start again, but the Dakota/VSS problem annoys me too. I don't know what to do about it.....

 

Disable VSS disgnostics in the ECM/PROM. This will keep the car from acting up when the VSS signal gets interupted.

 

If the VSS signal is ct of of the ECM then how will the speedo get a signal? I do have plans of changing over to all Autometer gauges long with an electric speedo so yes, I know I can disable the VSS from the chip but what about for right now with the stock cluster

 

I did that and it will still die when the speedo quits and I'm idling at a stop sign. WTF?!?! Also, now since I put my new clutch in, my speedo is working about 50% of the time. The other time it isn't working at all. I need to check power and ground to the SGI-5 but how can I tell is the SGI-5 is getting the VSS signal from the tranny? What should I check for at the input to the SGI-5.... resistance, current, voltage or what? In other words what signal does the VSS give off and send to the SGI-5? I know its just a pulse signal or something but how can I check for that when I'm driving and the speedo quits? I want to figure out if its my wiring, the SGI-5, the VSS, or what! THANKS!!

 

Dears,

my car is completely stock and is a V6 3.1 from 1991 but it looks like similar to my problem :

Once every hour of driving, I am loosing my speedometer, the needle just goes to zero and this lasts for a couple of seconds or a couple of minutes...during that period, the car is driving erratically and sometimes the engine even stall , but not always ( Most of the time I can continue to drive and go home with the car "behaving sluggish", so there is gas and sparks...

There seems to be no error code stored in the ECM (just code 12 of course)...I just put a new ECM in, but the problem is still there....since the problem is intermittent and disappears, it is very hard to diagnose and no mechanic can help me (I am living in Belgium, those cars are very seldom)....

My car is a Firebird from 1990 V6 3.1 automatic and with cruise control, and ADS SuperChip....I am getting desperate to find the source of the problem....any idea to solve this ? Did somebody experience the same and found a solution ??

Do you think it could be related to the problem you are discussing here or is different ? Sorry for my ignorance, try to learn....

Many thanks for your help.

John

 

Take it to your local speedo shop or a Street rod shop. I had the same problem when I tried to hook it up myself after a T56 swap. My local speedo shop has a dyno so it made selecting the correct position of the switches a breeze. 20 min. and $30 later problem solved.......... Good luck