Well Red as the Guys who came up with the fix I am more then willing to set you straight.

First, the ONLY thing the V-Mod contols is line Pressure. The only thing this has to do with shifting is to make sure you have enough pressure to apply the clutches properly. It does a fine job of this when tuning is not used.

Second, the main problem is that the signal is NOT being sent from the PCm to the transmission. If you never tell the trans to shift how is raising the line pressure going to make it happen? You could raise it through the roof but if you never tell it to shift you might as well shoot it.

The area we were having wear on the trans was from going from a 3.06 first gear to a 1 to 1 third gear at to slow a speed. just before the 60ft we would have to lift and nail it again to get third. so now we are appling 500+ TQ through a 2.7 STR(1350TQ) to a clucth pack that was not ready for it. oddly enough it kept living

In the end what it came down to was we could not force the PCM to make the shift no matter what we did. I ask Ed if he could help and in the beginning he thought he had it handled. this was good for people who did not want to use LT1 Edit as he scrambles the file so you can not use Edit on it. For the rest of us we had to keep plugging away. I gave up on OBD-I in the pits at a race in between rounds in Canada. we swapped my car over so I could race.. I have not had any problems since then. The car actually drives better now then it ever has and the trans mission seams to be more acurate then it ever was with shifting. Only thing we lost is WOT lock-up and I think that is tied to the missing crank sensor. I am sure we will find a fix for that also

If you have any more Questions feel free to ask. I am sure any of the skilled Transmission technitions here will be willing to help you in your quest. I am sure they will also tell you if you never send a signal to the trans to make a shift it is hard for the transmission it self to make the shift

Later



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OneFlyn95z28, on a similar topic...
Did you see this on the LT1edit list

I know that most are tuning for the street so kickdown isn't a concern. This is on a 96z,Vig3600stall(4200 really) and P1s-c,8psi/2ic setup.

Any clues?

_CAL

 

I would bet you are feeling the slip of the stall convertor. I play with mine all the time. hard to get used to. goes against my grain to hold it in the TQ band while it feels like it is slipping but it sure pulls hard and does not spin the tires

On a up shift you are usually over the stall range but on a KD many time you go straight into stall

Good luck!

BTW Many time lately I have just hitting Delete on the LT list. to much stuff not enough time

Ellis

 

Thanks, not a big problem (been that way for 5 years

-CAL

 

OK, so there are two different problems. I should have read the previous posts more carefully.
But not everybody with OBDI and a high stall experiences the shifting problem. My stall is rated at 3200 but when I mash it it stalls at 4500. So it is plenty high enough stall to experience the problem if it is a systematic problem, you know, something inherent that will always show up. But I have never experienced any problems shifting under wot.
So I am skeptical about this "problem". Especially when it involves hacking into code that nobody outside of GM completely understands. You may have made a problem go away that you were experiencing with your setup, but you may not really know why, or all of the implications. You may have created a problem that hasn't shown up yet. Or maybe not. It is great that you are happy with your setup now. But I think a large dose of skepticism is necessary when hacking into the pcm that has functions that none of us outside GM fully understand. That's how people can go around fixing problems that they may have created in the first place. ;D

 

Then again Red if we fell into that type of thinking we would never do any thing to our cars(What the dealer and GM Want's).

You see every aspect of our cars is controled by the PCM. To do ANYTHING to our cars would violate this perfect world it lives in and cause problems. So in essance yes IF i had never added gears,convertor or any other numbers of things to my car I would not have to "Hack" the code.

Then again it would be a very boring world

Good luck!

 

How much is involved in swapping to the OBD2 system?

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Vigilante 3200 Stall Converter, LS1 Driveshaft, B&M Supercooler 19,000 GVW, Moroso Cold Air Induction, MAF Translator Plus, LT4 KM, Fan Switch, Jet IAT, Hypertech Power Stat, MSD Coil, NGK TR6 Plugs, Jacobs Wires, Russell Wire Dividers, Scanmaster, 3.23 Gears, SLP Headers w/PBM Coating, Borla Adj Catback, Air Foil, NX System, Nitto drag radials, Hal rear shocks, BMR STB PHR LCA

 

Ellis buddy, I'm not saying don't do it, and I have done a fair amount myself. I guess I am just a bit more carefull about calling a problem solved when there are so many unknowns. But if it works (for now) and you are happy with it, then you're in tall clover.

 

Ok, I'm ready to do the obd2 conversion. Has anyone here done it on a '94 and exactly what wire would I have to run to the new diagnostic connector? Hope I have this right. I have to get an obd2 computer, 95+ diagnostic connector, obd2 knock module, and of course the wire I'm supposed to run from somewhere to somewhere else...anything else I'm missing?

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94 Z28 auto.White with white wheels.A few mods. 12.01 @113.5 N/A with a 1.67 60' on bfgs

 

Too bad there's now way to make your car operate like 93 with a non-electric transmission. Or is there?

Apparently they don't have this problem.

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'93 Camaro Z28 Automatic with a ZL1 hood.

No bottle.
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Thats all you need to know.
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Disclaimer: The opinions expressed by me are not necessarily supported or indicative of the Government of Canada or any other Federal Employee.

 

I saw in the posts above that it was recommended to run the vacuum modulator in blower cars.

How do you do that??

So far, my transmission is holding 437hp at the wheels. Some good parts, and I bumped up the part throttle line and temp settings with the LT-1 editor.

As far as the original question goes, can't you, with the LT-1 editor, just reduce the shift point mph on the 1 - 2 shift while keeping the shift rpm up where you want the shift to actually occur, I thought that PCM needed to satisfy both conditions before the shift would take place.

LWM

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95 A4, SLP catback, KBDD sfc, airfoil, Vortech S-trim, 30# SVO injectors, Autometer electric FP guage, boost guage, Hotchkis STB, AS&M headers, AFPR, Vortech Aftercooler, 3.125" blower pulley, 7" crank pulley, Vigilante 2,800 stall, MSD 6 BTM, SLP 35mm front bar, SLP 21mm rear bar, LT-1 editor ... , 437hp at the wheels. --- members.shaw.ca/mackenzl/LWMsZ-28/LWMsZ-28.html ... 01 vert in the making ...

 

Oh yes the dreaded OBD1 high stall shifting problem. I fought this stupid thing for two years until Ed recently found a fix for it.

It is completely off the wall, affects maybe 1 out of 20 cars. The ONLY fix for it is in the PCM, a vacuum module will do nothing.

Ed can now fix it (unless you have 3.42 gears) and I believe Bryan Herter has now caught on as well. It takes some trickery to get it to work but it does.

Talk to Ed or Bryan they know all the details.

My car didn't shift right for two years and now bangs off every gear even with my 4,100 Vigilante

-Andy

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1995 Impala SS
12.45 @105.51
Stock shortblock, no power adders, and full weight.

 

How recently did he find this fix? He tried programming mine back in January but it still didn't work.

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94 Z28 auto.White with white wheels.A few mods. 12.01 @113.5 N/A with a 1.67 60' on bfgs

 

My car did it with the 2800. So i didnt bother putting it back in. So know with the new tranny i can put the 3200 back in. What does ed charge for it 4DRSS?

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Vigilante 3200 Stall Converter, LS1 Driveshaft, B&M Supercooler 19,000 GVW, Moroso Cold Air Induction, MAF Translator Plus, LT4 KM, Fan Switch, Jet IAT, Hypertech Power Stat, MSD Coil, NGK TR6 Plugs, Jacobs Wires, Russell Wire Dividers, Scanmaster, 3.23 Gears, SLP Headers w/PBM Coating, Borla Adj Catback, Air Foil, NX System, Nitto drag radials, Hal rear shocks, BMR STB PHR LCA

 

Dave he got it working the mid/end of March. Look him back up, he's got some new tricks up his sleeve