I've read all the tuning guides, tuned on 747 setups but new to the $8D realm. I just recently helped a friend get a TPI installed on his Laguna S3. He's running a TH350 so no VSS is connected. It actually runs pretty damn good! Using an ostrich I took the stock AUJP bin and removed VATS to get it cranked and immediately went to work on the idle "XE268" cam ran rich. Driving around and logging with datamaster showed BLM corrections just as it should. I then took that log and ran it through vemaster and noticed it only corrected VE up to the idle rpm even though the datamaster log had corrections across the board. Is this because the no VSS / cell 4 problem? Does this mean tuning can be done on the VE tables but will have to be done manually and not through VEMASTER?

 

To attiain proper function, you will need some type of VSS signal for the factory style code to operate properly.

I believe for about $80 thru summit you can get an adapter that goes on the speedo cable at the trans to get the proper signal to the ecm.

In your case 4k pulse per mile.

do some searching, the adapter was posed about recently abd code 24/vss problems have been pretty covered

later
Jeremy

 

maybe I should ask the question what are the cons to no VSS? I mean the BLM appears correct in all rpm/map ranges, its just that when I ran it through VEMASTER it only updated to 750 rpm "idle". We're not looking to have functioning DFCO, Highway mode, egr, air, or any other VSS related functions to work.. just a simple engine controller that has a O2 closed-loop feedback routine.

 

Typically these things will happen.

1.)Your IAC will not reset and your idle will be unstable
2.)Decel fuel cut will not work and your engine will load up as you coast to a stall and even stall.
3.)The ECM will set a VSS code, IIRC Code 24.
4.)The IAC throttle follower routine will become messed up. It will act like the throttle plates are hung open and keep motoring on for a couple of seconds when you let off the gas (my G20 did this after a TBI swap)


Furthermore it is pretty pointless to try to achieve an accurate closed loop routine with one of its critical inputs missing. Not having a VSS signal will cause all kinds of random driveability quirks.

 

so far I have adjusted the TB so that warm the IAC counts are 0-5 and have not noticed any coasting issues or stalling of any kind "the ecu cannot bottom out the IAC trying to achieve the 750 rpm idle while the trans is pushing the motor decelling" so that solves the stalling issue. I cant see why it would load the engine decelling since it is attempting to maintain a 14.7 AFR anyway. EGR, AIR, DFCO and CPP have been disable with max temps set for enable temps.. all I want to know is why the vemaster only tunes 0-700 rpm..

 

U have 16 cells available for learning.

Your only using one which is the idle cell.

Thats what we have been saying, you need to get it out of cell 4, which means either getting a VSS or patching the code.

later
Jeremy

 

if I understand ECM operation correctly, the cells are used to keep a learned correction on a range of rpm/map BLM adjustment? so this would not be too neccessary if the VE tables were finely tuned? Also, no long-term BLM corrections would be saved for anything off idle? I think this will be an acceptable loss for now unless he wants to wire the VSS adapter.

 

Its a waste of time that your wasting your time on:-)

Not being mean, being brutally honest.

I wouldnt want to drive it that way, nor in particular trust it.

A stock setup might get by like this without badly noticeable side effects, but when experimenting with it on modified setups, it can be glaringly rich or lean depending on what its doing at the time.

There are quite a few ways to fix the VSS, so I would pick one and do it.

later
Jeremy