Sorry for all the new posts today...I finally have a chance to REALLY learn something about all this...being a grad student sux because I have to make sure that 500 people are all taken care of at the same time (I am a teaching assistant and research assistant to 3 different professors)
I just looked at one of the tech articles on the 3rd Gen home page that talked about doing a pseudo-bypass of the VSS. Wouldn't that pretty much eliminate the speed density part of the ECM programming or is the speed density thing controlled by engine speed? If it is controlled by engine speed, is there a way to eliminate the code 24 (Faulty VSS) from the error flags? I am having a tough time finding the "black box" that is supposed to be the VSS buffer in a junkyard and none of the local parts houses list it as a replacement part. The sensor part is easy. I have a speedo cable from a 1986-ish Wagoneer that has pretty much the same sort of thing in it with two wires coming off of it. I am fairly certain that it will work with the GM VSSB.
Again, many thanks in advance.

 

I know there is a lot of controversy over the use of the VSS. I personally don't run one on any of my conversions. Street or trail.
Not that I wouldn't run one on the street, just haven't had the time to get one and put it in. I figured it would make an easy upgrade to the cruise control.
I disable the fault when I burn the chip.
I do hook up the park neutral wire. I just tied it into the neutral start sw. I can watch the flag on winaldl and verify it works when I shift it out of park.
If you have tuner pro then just click on malf flags 12-24 and uncheck 24.
HTH

 

Done. Thanks, Bill usn-1
Neutral start switch already "tweaked" to work with the (Chrysler) TF727 transmission
KenG
USN (CVN-71, CVN-74)

 

Good deal,


CV64 - 2K, 2K1
1 yr 2mo 10 days.
It was fun but was enough.

 

Ok, I was not using a Vss either because I cound't find the buffer either. I forgot to take it out of the truck I got my heart from. I got a speed sensor from Street and Performance that did the trick. I just hooked it up to ground and to the signal line for the Vss. It worked without anything else needed! So if you want another option that would be one. I swear it is not making any difference in the running of my rig though.

Marcello

 

The buffer box you are looking for is called a 4-out buffer. Even has it on the label. They are yellow or white in color, molded plastic. About 4 x 4" and an 1 thick (about).

Can be found on the TBI Camaro's and Firebirds of ca '87-'92 MY. Can also be found on ca '89-'90 Caprice's.

Under dash typically on passenger side. Some are on driver side.

The Grand Wagoneer VSS is an 8 pole device and will have double speed output (20 mph will show as 40 mph). However, it interfaces directly to the 4-out buffer.

Ahh, thought I had a pic, attached. . .

RBob.

 

So my Waggy VSS will tell the ECM that my speed is 2x what it really is? This doesn't sound good. Is there a way around that or am I pretty much screwed? The problem here is that I don't think a GM speedo cable will fit in my transfer case speedo out mechanisms (Dana 300 transfer case).

 

Yes, but does it matter? The two important areas the VSS controls is the idle and the TCC. The idle is covered as the VSS operates and will show 0 when at a standstill.

If you have a TCC just double the MPH settings. Or can add a 74LS74 flip flop and do a divide by two on the 4-out buffer PCB.

I thought the Wagoneer VSS's had the same fittings as the GM stuff? This is the one low on the fire wall with the 18" or so cable from the speedo?

RBob.

 

No problem here then. As long as the ECM knows the vehicle is at a standstill, I'll be happy cause it will actually idle.
Don't need this one either. My TC is a non-lockup TC (TorqueFlight 727 tranny) and doesn't have provisions for computer control
Yep, that's the one. If it does in fact have the same fittings, I may try to put the GM VSS in the cable in place of the OEM Waggy VSS. I am only doing this because I am a beginner at this stuff and I really don't want to screw up a nice new TBI system by omitting part of the controls.
Thanx, Rbob.

 

I ran into this problem on a Jeep that I was helping diagnose. My friend swaped in a 305 TPI setup in this guys jeep for him and it wouln't idle at all, had to keep the revs up in neutral at a stop. It was using a hypercrap chip and a 165 MAF setup. They didn't have the VSS hooked up and I told them that was the problem. As a crutch we just set the TPS up above the idle threshhold and it idled fine then. This fix is way hack but the guy was happy. Just for reference the Hypercrap gave him 32 deg total and was way lean, it pegged the blm's at 145. All he had added was headers and dual exhaust.

If your runnin a 747 you can use the torque converter lockup as a shift lite if your not using it to lock your converter. Just set the turn on points at your desired rpm and zero out the speed thresholds.

 

I hadn't thought about using the TCC as a shift light. I am using a TF727 automatic coupled to a Dana 300 transfer case. I am not using a 747...8746 here. I have simply left the TCC stuff unhooked and taped off.
I am looking for the VSS pretty actuvely. The last resort is to to go the stealership looking for it.

 

Yeah stay away from the stealership. Even there it shouldn't be more than 20 bucks I don't think, but then again it is the stealership.

Actually the shift light logic for manual cars was done the way I described above except it was tuned to give you the best shift point for milage. I'm gonna have mine setup to give me two different shift points depending on which gear i'm in, using the high and low gear input to swap between them. Well thats if I can talk my self into not hooking it up to the tranny like I should. I have flipped that little switch on my dash to lock the tranny up for so long I dunno If I can let the ecm do it LOL

 

See, I have an automatic tranny, but it is a 3-sp non-lockup. I THINK I could convert it to a lockup type if I wanted to swap the front pump and input shaft, but I REALLY don't want to do that and I really don't think it'd do any good as these trannies have a hydraulically controlled lockup mechanism. I rebuilt this tranny myself about 2 years or so ago and it works great...will REALLY hold a LOT of power and has great shifts to boot. I set it for KILL. Believe it or not, the Chrysler TF727 is a really stout tranny...it came stock in cars like the HemiCuda, so it should hold up fine in my 2500-lb Jeep with the 360 up front.
I haven't had a chance to find that buffer yet, but I will have all the time in the world come this weekend. This semester is over for me on Thurs and I will have PLENTY of time for Jeep related projects...
...Now if I could just get my hands on the AutoProm...

 

Yeah my week is over at 8:00 AM on thursday morning too. Can't wait to get that last exam out of th way. I'll finally have time to get those TBI articles done.

 

Ahhhh.....that's better....the Fall 2003 semester is history. Thank ***!!! Now I can dig into the Jeep a little more.
I still haven't found that 4-out buffer. Rbob, could you post the GM part number again? I was too stupid/lazy to write it down the first time.
The ignition harness adapter should be here after the first of the year. Everything else is in place....except one crucial part (not the AutoPROM)...I still have to mount the Holley fuel pump and figure out how to get power to it. More on that later....

 

I really don't have a part number, only what is on the pics. I get darn near everything from recycle yards. The part number may be what is on the label. If anything ask for a '92 Camaro LO3 TBI VSS (4-out) buffer box. That should be enough for a decent parts counter dealership.

RBob.

 

One crucial word, Rbob...DECENT...we have good parts houses here in Rockport, Texas. They are good if you want a set of neon lights or a chain steering wheel for your low rider. How about a fake NOx kit...or the little flashing valve stems? Curb feelers anyone? Maybe I could lower my Jeep and put a set of under-the-frame neon lights that pulsate with the overexaggerated bass beat because my alternator is too puny to supply that much current all at once. (Just kidding here, guys, no flames or anger intended...just a little good natured humor I actually have a 100-amp GM 3-wire alternator on my mill) I have asked the three parts houses here for the VSS buffer and not a single one of them show it as something that even exists.
Anyway, the pictures no longer appear in this thread. That's whay I asked for the number that is on them. I haven't called the stealership yet...I am kinda afraid to hear what they might say.
EDIT:
BTW...if you wanna REALLY get sick, check out my jackass sis-in-law's truck. She really DID put a set of those f-ing neon lights on a lifted Z-71 with a TBI SBC (400ci, I think) under the hood. I laughed my *** off when I saw it and she sincerely asked me why I was laughing.

 

Well, if it's ECM controlled. . .

Just kidding too. The pic still shows up here. From the label:

4 OUT BUFFER
25071437

RBob.

 

Thank you.