Hi Guys,

I have read lots of threads about this but none seem to be this exact problem. I swaped a '91 L98TPI into a '92 305 TBI car. I used the whole harness and computer from the donor car and all pins are used. The car runs great, and all gauges work except the speedo. The car does not feel like the TQ converter is locking up as it should. Swapped out the VSS to the digital one required for TPI, and the speedo still does not work at all. Do I need to find the old buffer box and do some rewiring? Does installing the new harness and VSS bypass the old buffer box, or is that the roadblock? I have a speedo cluster from a '92 TPI car I can install if that will make a difference.

Thanks for your input!

 

I'd also like to find the answer to this since i will be installing a tpi in place of a tbi and need to know

 

i have same problem

 

what ecm you running? is it a cable driven speedo head? are you putting in a 90-92 tpi ecm or the 86-89 ecm? I can help a little. have did tons of research so i'm hopeing i got what i need.

 

[quote=greg320;4481001]Hi Guys,

I have read lots of threads about this but none seem to be this exact problem. I swaped a '91 L98TPI into a '92 305 TBI car. I used the whole harness and computer from the donor car and all pins are used. The car runs great, and all gauges work except the speedo. The car does not feel like the TQ converter is locking up as it should. Swapped out the VSS to the digital one required for TPI, and the speedo still does not work at all. Do I need to find the old buffer box and do some rewiring? Does installing the new harness and VSS bypass the old buffer box, or is that the roadblock? I have a speedo cluster from a '92 TPI car I can install if that will make a difference.

Thanks for your input![/qu
Okay if you got the 4k vss and its wired directly into the 92 ecm. theres a 2k and 4k output from the 730 ecm and you should be able to run that to the old wire for the vss buffer and all the things the vss buffer runs i would think would work.

 

ok so i dont need to delete the buffer box.....i have a 91 camaro formally tbi305 swaped to 350tpi out aof a 92t/a everything runs good no speedo i will change the vss and see what happens but i dont really get y i am doing this just b/c my speedo worked before....??

 

Ok, lets see if I can help you.

You do need to get rid of the buffer box.

There is a brown wire comimg from the speedo to the buffer box, you need to remove it from the box and put it in pin #B11 on the 7730 'puter, as the 7730 now feeds the signal to the speedo.

If you have cruise control, you need to move the red wire to the C1 of the 'puter.

HTH

 

That i would think would work

 

True, it would work, but swapping the pin on the C207 and bypassing the buffer box takes 10 mins and doesnt require disemboweling the dash to run one wire to the inst cluster

Its really quite simple, if you pulled off the swap you can handle this. Locate the C207 engine side (clear) and move pin D (gry) to pin K (empty)

Next find the buffer box and unplug it. Connect pins C and F with either a runner wire or strip them and solder them direct

Thats it