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RE: [VORTECcruisers] Re: VSS options



I have speed sensors on both of my Vortecs that are equipped with manual transmissions (one an SM465 and the other an NV4500). I have monitored the performance of the engines and sensor readings on and off the highway using an AutoTap OBDII scanner and laptop. The VCM most definitely does adjust the fuel:air mixture at highway speeds based on the signal from the VSS (the mixture is leaned out at higher speeds).  And as Davis notes, the idle speed is also increased. The increased idle speed with the VSS can take 30 seconds or so to reset (based on MAF and other sensors) and can be a distraction at stop lights. 

I think the consensus is that the Vortec engines do not require the VSS to operate well. At highway speeds the engine does run more efficiently with the VSS, but whether or not there is a noticeable improvement in fuel consumption, I don't know.  It would be interesting to run a tank of gas on the Freeway with and without the VSS to see how much of a difference it actually makes.

The VSS signal IS an absolute must when using an electronic transmission (4L60E or 4L80E).

-----Original Message-----
From: fj45456040 [mailto:delawrence@xxxxxxxxxxxxx]
Sent: Wednesday, February 23, 2005 12:55 PM
To: VORTECcruisers@xxxxxxxxxxxxxxx
Subject: [VORTECcruisers] Re: VSS options




My understanding from FI Specialties about the VSS was that the 
computer would use it for such things as determining idle speed and 
leaning the fuel mixture at cruising speeds.  An example he gave was 
that on the highway it would maintain a higher idle, but getting off 
the highway it (the VCM) wouldn't know immediately to lower the idle 
without the VSS, but would eventually lower it based on readings from 
MAF and other sensors.
I'm not too worried about a little highway fuel efficiency, but want 
to make sure I'll be able to maintain a good idle, especially 
crawling.
Thoughts or experiences?
David

--- In VORTECcruisers@xxxxxxxxxxxxxxx, "Jack Rice" <jrice@xxxx> wrote:
> The th350 is not an electronic transmission. It cannot communicate 
with the Vortec VCM and hence could not deal with a VSS signal even 
if you provided it. Consequently you don't need a VSS, especially if 
it is going to be used primarily for crawling.
> 
> -----Original Message-----
> From: Ed Gilbert [mailto:vorteccruiser@xxxx]
> Sent: Friday, February 18, 2005 9:52 PM
> To: VORTECcruisers@xxxxxxxxxxxxxxx
> Subject: Re: [VORTECcruisers] VSS options
> 
> 
> With an automatic trans, you will need a VSS.  If you need a Downey 
pulse generator,
> I have the speedo-cable-driven generator with the related parts, 
which is for sale.
> I discovered I didn't need a VSS with my setup.
>  
> Edwin Gilbert - Alta Loma, CA  - TLCA #5659 - So. Cal. TLCA
> 1977 FJ40 - 5.7L Vortec - NV4500 - Split xfer case
> 
> ----- Original Message ----- 
> From: fj45456040 <mailto:delawrence@xxxx>  
> To: VORTECcruisers@xxxxxxxxxxxxxxx 
> Sent: Friday, February 18, 2005 9:20 PM
> Subject: [VORTECcruisers] VSS options
> 
> 
> I'm going to put a 4.3 sfi motor with a th350 to a marlin crawler 
> (mini truck cases) and trying to decide 1. if I need a VSS and 2. 
> what are my choices if so.  It is a rock crawler and will see 
> occasional road use, but no emissions are required.  I'll run 
> whatever emissions I need to, depending on the computer I get.  
> Downey has a 1 1/2" tcase adapter or a 3 3/4" that can be fitted 
with 
> a reluctor ring.  I haven't priced the reluctor option yet.  
Talking 
> to Fuel Injection Specialties, the guy said they can put a 40 tooth 
> ring on the rear yoke of the t-case, but then it's exposed to the 
> elements and mud etc may interfere sometimes.  That option is about 
> $160.
> Searching the archives came across the Downey 2 pulse and generator 
> as an option (from 2001 posts).  I need to call Downey, but are 
there 
> other options out there now that would allow me to go with the 
short 
> adapter and not spend a ton of money?
> thanks,
> david
> 
> 
> 
> 
> 
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