amongst other things, it is what makes your idle hang as you are slowing down and pop the car into neutral (idle) - if the car is stalling or the idle is falling too fast while moving at idle, it could be bad (the IAC needs to be working decently as well).
ive never really noticed the VSS in action in this regard, on the stang. i have a 1st gen eclipse, and as soon as the car rolls one bit, the revs pick up - the VSS at work.
well ive been dealing with a rough idle, i got a new iac, new tps. everything is dialed in and it runs pretty good but check it out. ill come to a light and the idle will hang then itll drop but if i hold the clutch to the floor the idle will drop even more@! im thinking it has something to do with the vss, the engine is practically brand new, less than 5k miles on it. whatcha think?
I have the same problem...but after it drops "hard" it will start surging from 500 to 1500 rpms...still have no idea. All the codes I pulled where for lean condition and EGR (but my EGR is new) so the codes were no help.
I have replaced everything...IAC, EGR, TPS, PCV, O2, cleared the cats. Cleaned the TB, MAF, intake. Gave it a tune up (complete to include fuel filter), nothing has helped. Secondary Air system?? You mean from the exhaust?
SMOG is still intact....I have not messed with the VSS...yet. My Speedo needle does bounce around like its on crack on a rare occassion. You have that problem also? (Happened twice in the last 6 months for about 5 minutes)
ok so i unplugged the vss and then i decided to unplug the iac while the car is running and the idle dropped but the surging also stopped. i drove around for a few minutes and i like the vss unplugged, the idle drops better like a carbed car. the "idle hang" is much less. i talked to a buddy who had a car that did not have cruise control and when he converted to mass air he didnt even add a vss and hes been doing fine.
My conversion has no VSS at all - no idle surge issues, and the slow idle drop is present - I believe that's built into the ecu's programming - not as a function of vehicle speed. Mine will gradually return to idle over a 2 or 3 second period whether I'm rolling to a stop or slip it into neutral while rolling along at 70.
yes mine does that too. but when i hold the clutch pedal to the ground itd drop the idle another few hundred rpm. now with it unplugged it drops that few hundred rpm automatically.
My car seems to be doing almost the same thing but it just started yesterday after taking it the track I made one run went to make anouther and all of a sudden my alternater was dead battery died put a new alternater in now it surges like a basterd everytime I come to a stop now I tired disconenting the eec but that did not help so maybe I will try the vss