Docked Wage

I've read about the issues with not having a VSS on a LS/Manual Trans combo and having stalling or almost a stall when the clutch is depressed. The explanations I read said it had to do with the IAC valve and not being able to transition quickly enough.

My question is that since the newer style DBW throttle bodies don't use an IAC is this still an issue?

I'd like to make use of an old Muncie 4 Speed and not have to deal with fabricating a vss setup if it's not really required with the new throttle bodies handling the idle.

Thanks, Ken

garys 68

iTrader: (1)

I've done 2 DBW manual trans swaps (an 02 and 05). I was able to repoduce the stalling issue in both. All you need is a dakota digital pass thru vss hooked up to the muncie speedo output. It doesn't even have to be calibrated correctlt.

soundengineer

iTrader: (16)

you need a vss as it reports to the pcm and gets translated into speed...which teh pcm uses for various calculations....including idle while moving, and coming down to idle while moving.

while some things may seem to work with an uncalibrated vss as gary is saying....
they do not work correctly and can make tuning a pain in the ***

Docked Wage

Don't you guys sleep?

Thanks for the responses. So much for hope as a strategy.

I'll plan to get a vss in the drivetrain somehow.

Regards, Ken

garys 68

iTrader: (1)

SEN-01-4160, screws into the Muncie/T10 speedo output. Your speedo cable screws into the VSS. I would suggest buying the short adapter cable (not listed on their website). It can get tight in the tunnel.
http://www.dakotadigital.com/index.c...rod/prd109.htm

gagliano7

On my drive by cable 1999 pcm, 2004 5.3 in a 1992 chevy pickup i didn't have the vss hookup and it ran fine.But i kept getting a PO507 code.Once i hooked up the VSS i no longer get the code.

Docked Wage

Anyone ever try hooking up and programming in the CPP (without a VSS hooked up and turned off) so the PCM sees the clutch pedal was depressed?

garys 68

iTrader: (1)

What are you trying to do? I left out the CPP switch on both my swaps.

Docked Wage

I'm wondering if the stalling or near stall might be attributed to the CPP not being hooked up.

Not sure what the CPP does in the software but I would expect that when the clutch pedal is pushed the load percent drops to zero all of the sudden. My guess is that if the CPP is hooked up and turned on in the software that there might be some sort of compensation that happens.

I'm not a tuner so I can't say. Someone that is intimate with HP tuners or the Software in the PCM might be able to tell me that I'm on to something or if it's a dead end trail.

garys 68

iTrader: (1)

A $50 vss that takes 5 minutes to hook up sounds easier.

LS1MCSS

iTrader: (18)

The CPP has nothing to do with one trying to stall out. It's only to keep cars from starting without pushing in the clutch. The VSS, or lack of, will cause stalling.

garys 68

iTrader: (1)

Well the CPP switch does shut down cruise control if you're using that. Not sure if it does anything else in the ecu.

LS1MCSS

iTrader: (18)

It does do that, but won't cause it to stall. There's a good chance that you could go into the tune and change settings on the DFCO and help, if not stop, the stalling even without a VSS. I wish I had one here to play with a little to see if that would work.

garys 68

iTrader: (1)

Yeah, but adding the pass thru vss is easier than trying to hook in a cpp switch on an old car.

Docked Wage

Ok. Thanks again for the help.

Ken