Okay, I have been reading thirdgen for several years and got a lot of help . Now if I don't get kicked off for asking this, I'll be okay. I put a L98 in my 55 Chevy from an 87 Vette. I changed the TPI to speed density with a 730 ECM. I took a harness from a 92 Z-28 at the boneyard and deleted everything not TPI. I had a prom burned to delete the VATS, EGR, switched it to standard shift and changed the RPM to 6,500 (just because the guy burning it wanted to). It will never be pushed that hard. I'm running a 700R4 tranny and used a Painless stand alone harness for the lockup. Also I'm using a cable driven speedo and I'm not sure what year the driven gear adapter is I used, but it replaced the original electric speedo adapter. This car runs great. BUT, since I didn't use a VSS, I'm having a bit of a problem on deceleration. When I slow to a light or just stopping, the RPM stays a little high for a few seconds.
I didn't remove the VSS wiring but rather I coiled it up and taped it.
Now if someone would be so kind as to advise me on what is needed to fix this, I would appreciate it. I might be able to sort it out after reading everything I can find, but to be honest, I'm feeling a little lazy these days.

Thanks in advance.
Mike

 

TPI Parts.net (Site sponsor - see link above) has some dual purpose VSS's for sale. I just bought one for my dad's TPI 79 Malibu. It has a cable driven output, and a standard VSS connection. Make sure to get the correct one for your type of ECU (90-92 '730). This (discontinued) part was used on police cars that had cable driven reference Radar systems, and 700R4's, and ECUs that needed that VSS signal. It's $85 or so, plus $5 shipping on their Ebay store. Not sure if ones available right now, but send them an email and they'll surely be able to get one to you ASAP.

With this part, you could switch your 700R4 to computer controlled lockup if you're not satisfied with the stand alone setup, but that's totally up to you.

 

Thanks Jeremy. I see the steel stem sticking out of the end where the driven gear goes, does this accept the regular driven gear?



PS If I just add the VSS back into the system, will that be all that needed? Also, if I leave the prom set for standard shift, will the VSS control the RPM as it should? It would be easier not to get into running the P/N wiring thru the shift linkage.

 

- about the driven gear question - I would assume so, but I haven't ever changed a VSS personally.

- about the P/N switch - It would be better with a P/N switch. It will probably "flare up" when put into park or nuetral, and perhaps almost stall when put into gear. If you have the throttle screw (minimum air) set high enough, the stall likely won't happen. I think you'll just have to see how your setup responds to just a VSS. When you say the RPMs stay high, are you still in Drive? or do you drop it to nuetral and have that problem?

 

I don't have a tach on it, but the RPM acts normal shifting from park to drive or reverse. When coming to a stop in drive I feel a little resistance to low idle with each downshift. Once I am stopped for 5 seconds or so, the idle is fine. I don't think I should feel the downshifts. It feels just like a carb car with the idle set too high. My hope is the VSS will clue the ECM that the car is stopping. Either way, I feel now (with your input) that the VSS is the basis for the problem. I'll get the VSS and we will see what we have then. Thanks for the help.

 

Well, I fixed my screen name back to what it was. I'll keep you posted.