I've had enough with my carb and am switching over to TBI. The TBI from a 88 350 has been swaped over to my carbed 350 , So I take it out for a test drive and get a code 24 ( VSS ). Turns out I need one. My GMC manual says I need 2000 pulse/mile, sounds easy but all I can find at the parts store is a painless or autometer elec. speedo sender at 16 pulse/rev.

Can someone tell me if 16 pulse/rev is close to 2000 pulse/mile.

thanks for any help, and while your looking is an ECM for an auto going to work with my standerd tranny?

right now the truck has a bit of a fluctuating idle and a code 24 (vss). otherwise it runs great

Hey man!

Assuming you are running a 73-86 truck, you can very easily install a stock VSS. They were installed on the speedometer head of trucks from 83-86 with cruise control, and provide the 2000 pulse per mile signal you are needing for the TBI ECM.

Simply need to swap the speedometer out (will fit on any 80+ speedometer housing with no modifications, need to cut the bezel a bit on anything 79 and down) and if you're worried about the color of the gauge matching, the fuel gauge as well.

It will reduce you from a 160 km/h speedo to a 140 km/h, but otherwise has no disadvantages. It is entirely possible to retrofit an older 160 km/h speedo with a VSS, like I did with my 80, but it is a bit more involved than just a speedo swap.

Russ

You could use the methos described in your first response, or buy a 60115 painless 2000 pulse speed sensor adapter from Jegs, Summit, or www.jagsthatrun.com . Some people bypass VSS by incresing the idle speed in the programming, but it still never operates quite right. Have someone burn a new chip for you that uses manual trans programming.
http://www.painlesswiring.com/webcatalog.php

So if I am using an 89 350 tbi without vss hooked up, what will it do to the way it runs?

Its a tbi from an automatic truck.

So if I am using an 89 350 tbi without vss hooked up, what will it do to the way it runs?
The ecm needs to see that the vehicle is moving for several reasons. The EGR, Highway mode, and torque converter lockup won't function without it. It also needs to see how fast it's going to adjust the IAC. Some common complaints are that the motor will dies in some deceleration situations.
My question to anyone doing such a conversion and trying to bypass VSS. Why go through all this trouble and not make it the best it can be?

I never said I was trying to bypass. I never realized my motor had it. The motor is from an 89 pickup. I am running a t350 tranny and a 203/205 doubler. I have a 454 tbi on it and have never got it right. Its got a hypertech chip. Main problem is some pretty good hesitation off the line. It did it even with the 350 tbi. And it runs a little rich.

dentedup, sorry to hijack. Mrwillys, heres my post about my problems.
http://www.pirate4x4.com/forum/showthread.php?t=476652

You can also check with Stealth. Just do a Google search. Very helpful.
OR, you can always go with Affordable fuel injection. I don't have VSS in my setup.

I would go back to a completely stock 350 setup. Buy a cable from AKM electronics and take some data recordings and send them to someone who can burn tbi chips. You could do it yourself starting at www.moates.net . You probably have fuel tables that are out of parameter and the learn function can't makeup for it. As mentioned above AFI has great handle on these wet injection systems.
I never said I was trying to bypass. I never realized my motor had it. The motor is from an 89 pickup. I am running a t350 tranny and a 203/205 doubler. I have a 454 tbi on it and have never got it right. Its got a hypertech chip. Main problem is some pretty good hesitation off the line. It did it even with the 350 tbi. And it runs a little rich.

dentedup, sorry to hijack. Mrwillys, heres my post about my problems.
http://www.pirate4x4.com/forum/showthread.php?t=476652

You can also check with Stealth. Just do a Google search. Very helpful.
OR, you can always go with Affordable fuel injection. I don't have VSS in my setup.

ya I was very close to going with Affordable fuel injection, very helpfull outfit but I came across a 88 tbi system for nothing and am now trying to get it to work on my rig, like I said in my original post is a 16 pulse / rev the same as a 2000 pulse / mile ?

Most American speedometers operate at 1000 revolutions per mile. If you have a 16 pulse per revolution speed sensor it is a 16,000 per mile. So your question; are they same? NO.
What you need I already posted a link to. You need a 2 pulse revolution, or 2000 per mile.
ya I was very close to going with Affordable fuel injection, very helpfull outfit but I came across a 88 tbi system for nothing and am now trying to get it to work on my rig, like I said in my original post is a 16 pulse / rev the same as a 2000 pulse / mile ?

thanks for the info mrwillys