Time to get banned, VSS mod and fuel system - Boost Forum

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Time to get banned, VSS mod and fuel system
Saturday, November 11, 2006 3:58 PM
OK, to start off. THIS POST IN NO WAY DEALS WITH, OR PERTAINS TO THE ACTUAL PROCESS OF DISABLING OR MODIFYING THE VSS ON ANY SORT OF VEHICLE. I HAVE NO INTENT OF DESCRIBING, HELPING, OR HINTING AROUND TO ANYONE OF HOW TO DO THAT.

That being said, the 03-05 Ecotecs are known to pull injector pulsewidth to achieve the magical 14.7 air fuel ratio, which is not good if someone wants to run boost. I have heard minor rumblings from people that pertains to the VSS mod and bypassing the computer's desire to achieve constant stoichiometric air/fuel ratio.

Could someone please explain how it is possible to bypass the 14.7 AFR desired to allow for boost??? Does it involve disabling the VSS??? IF so, or not, what are the steps necessary to do so??? I know it has been done.

That being said, I will once again reaffirm: THIS POST DOES NOT, AND IS NOT INTENDED TO EXPLAIN HOW TO PERFORM THE VSS MOD. IT MERELY ASKS IF THIS MOD IS NECESSARY TO ALTER FUEL RATIOS TO ACHIEVE DESIREABLE AFR'S ON AN 03-05 ECOTEC J-BODY.

Thanks for any and all help.




Currently #4 in Ecotec Forced Induction horsepower ratings. 505.8 WHP 414WTQ!!!
Currently 3rd quickest Ecotec on the .org - 10.949 @ 131.50 MPH!!!


Re: Time to get banned, VSS mod and fuel system
Saturday, November 11, 2006 4:07 PM
Disabling the VSS does NOT alter fuel. Pulling the O2 sensor off would, but it would also pull timing.





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Re: Time to get banned, VSS mod and fuel system
Saturday, November 11, 2006 5:13 PM
It was rumored from hypsy that disabling the vss put the vehicle into open loop thus adding more fuel to the situation but with this said that is no way to add fuel to your vehicle for boost. If your worried get the begi fmu or hpt which would be the best form of engine management. If you want to go a different way megasquirt is run by multiple org members who would be more than willing to give you some info. Whether the rumor was true you would have to speak with someone who has had this mod done. HPT can not only tune your af ratio but can also raise rev limiter, speed limiter, and dozens of other aspects of the stock computer.


*2012 mazdaspeed3*
Re: Time to get banned, VSS mod and fuel system
Saturday, November 11, 2006 5:14 PM
ron , can hpt change that in the 03-05's ?? by changing the pe tables







Re: Time to get banned, VSS mod and fuel system
Saturday, November 11, 2006 5:41 PM
find someone with HPTuners, pay them $100 for 2 credits, unlock your car and set the power enrichment to 0 rpm, problem solved



Re: Time to get banned, VSS mod and fuel system
Saturday, November 11, 2006 5:56 PM
I know that there is more to a forced induction fuel system than simply ading more fuel. I already got my fuel system mapped out. Walbro 255, Accell 150144 (426cc) injectors, adjustable FMU, and adjustable FPR. I was just wondering wether doing the "unmentionable" mod would bypass the computers desire for a constant 14.7

Unless, of course, someone here would be interested in tuning my car with HPTuners.




Currently #4 in Ecotec Forced Induction horsepower ratings. 505.8 WHP 414WTQ!!!
Currently 3rd quickest Ecotec on the .org - 10.949 @ 131.50 MPH!!!

Re: Time to get banned, VSS mod and fuel system
Saturday, November 11, 2006 9:17 PM
Unplugging the IAT sensor is supposed to put the car in open loop also. It is easier to do. Just a thought.



2004 Cavalier. Razzi. (Sold)
1998 Corvette. Some mods.
1992 Typhoon. Lots of mods.
1994 Civic VX 44MPG
Re: Time to get banned, VSS mod and fuel system
Sunday, November 12, 2006 6:02 AM
Darkstars wrote:find someone with HPTuners, pay them $100 for 2 credits, unlock your car and set the power enrichment to 0 rpm, problem solved


Set it back but certainly not to 0 You want the computer controlling/altering the fuel during normal driving conditions.

I'd set it to 3100 or 3200 depending upon how fast you typically drive on the highway. If you always cruise at 80 or less 3100 should be fine...


12.770 @ 111.99 Intercooled Eaton M62


Re: Time to get banned, VSS mod and fuel system
Sunday, November 12, 2006 6:30 AM
Airtonics wrote:
Darkstars wrote:find someone with HPTuners, pay them $100 for 2 credits, unlock your car and set the power enrichment to 0 rpm, problem solved


Set it back but certainly not to 0 You want the computer controlling/altering the fuel during normal driving conditions.

I'd set it to 3100 or 3200 depending upon how fast you typically drive on the highway. If you always cruise at 80 or less 3100 should be fine...


You can set it to 0, there are other things that make it go into PE like the TPS position. Setting the RPM to 0 makes the engine go into PE as soon as the TPS setting is satisified, so as long as you have that up high enough, the engine won't be in PE unless you step on it.





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Re: Time to get banned, VSS mod and fuel system
Monday, November 13, 2006 10:00 AM
I remember the discussions around the whole VSS issue... someone claimed it was only in the 04 and 05 cars... not the 02 and 03 ones. I don't know what changed between the two... that's all I know...





Re: Time to get banned, VSS mod and fuel system
Monday, November 13, 2006 1:41 PM
http://www.j-body.org/forums/read.php?f=40&i=95277&t=95266&p=1
JimmyZ wrote:It depends on the car... in your case, Phil, probably not. In the case of newer cars, like 2004+, probably so.

The EPA is constantly breathing down the neck of manufacturers to reign in emissions under a laundry list of conditions. Idling, accelerating under load, accelerating with light load, decelerating, revving in neutral....etc....you name it, they've got a requirement for it.

Add to that the fact that more and more states have added "treadmills" to their emissions testing and you've got a complicated situation. Now you've got a mandate that says the computer has to keep an increasingly tight leash on emissions while the car is moving at various speeds under wildly varying load conditions. Responding to this, GM revised the coding in the ECM to make the VSS part of the emissions sensor block, with all the associated pass/fail results. If you remove/cut/disable any emissions related sensor you throw the computer into "limp" mode...open loop, lower fuel ratios, retarded timing, etc. Gone are the days when WOT meant fuel dumps and 11.5:1 A/F rations. Now in closed loop, even at WOT under full load, the ECM sits there and regulates it like Scrooge counting pennies.

Cutting the VSS is a simple way to force the computer into open loop without sacrificing the input of other sensors. Remaiing sensors are still read, unlike some older ECMs that went into COMPLETELY open loop operation.

So, to answer the question...YES, on newer vehicles utilizing GM's new code removing the VSS will allow the computer into open loop mode. 2004+ is a near definite that you've got this code. 2003 is iffy. 2002 and older, negative.

On a side note, just for my own curiosity....can't we all just get along? I seem to recall everyone is here for the same reason, but lately it's been all about "oh, I found out first" or "oh I'm MORE stock" or "so-and-so is keeping secrets". Give me a @!#$ break people. Grow up, tune your engines, and have fun while you're doing it. Check your attitudes at the door, and don't assume anything. ANYONE can teach you something new at any given time...especially when you don't expect it, so keep your eyes and ears open.






09:f9:11:02:9d:74:e3:5b:d8:41:56:c5:63


Re: Time to get banned, VSS mod and fuel system
Monday, November 13, 2006 2:13 PM
best way to tune the car we be via hp tuners , using the stock (non-s/c reflash)


and not worry about mickey mousing something that shouldnt be messed with to cause misleading info to the pcm







Re: Time to get banned, VSS mod and fuel system
Tuesday, November 14, 2006 5:14 AM
[quote=97trd(???™)]best way to tune the car we be via hp tuners , using the stock (non-s/c reflash)


and not worry about mickey mousing something that shouldnt be messed with to cause misleading info to the pcm

Do we have anyone doing this setup yet? Will someone be willing to create a base line Tune then they are willing to share for all of us that use the m62?
Re: Time to get banned, VSS mod and fuel system
Tuesday, November 14, 2006 5:30 AM
Shifted wrote:
Airtonics wrote:
Darkstars wrote:find someone with HPTuners, pay them $100 for 2 credits, unlock your car and set the power enrichment to 0 rpm, problem solved


Set it back but certainly not to 0 You want the computer controlling/altering the fuel during normal driving conditions.

I'd set it to 3100 or 3200 depending upon how fast you typically drive on the highway. If you always cruise at 80 or less 3100 should be fine...


you can set it to 0, there are other things that make it go into PE like the TPS position. Setting the RPM to 0 makes the engine go into PE as soon as the TPS setting is satisified, so as long as you have that up high enough, the engine won't be in PE unless you step on it.








Re: Time to get banned, VSS mod and fuel system
Tuesday, November 14, 2006 11:06 AM
why not swap to the 02 pcm, thats what im donig



2007 GM Tuner Bash...HELL YEA
PA,MD,NJ,DE,NY and all states north caravan
Re: Time to get banned, VSS mod and fuel system
Saturday, November 18, 2006 7:52 PM
JimmyZ. Thnak you for posting that thread. I searched because I vaguely remember seeing this topic a long time ago, and being as I wasn't considering going forced induction at the time, I didn't pay much attention. You have helped me more than you know. Thanks.




Currently #4 in Ecotec Forced Induction horsepower ratings. 505.8 WHP 414WTQ!!!
Currently 3rd quickest Ecotec on the .org - 10.949 @ 131.50 MPH!!!

Re: Time to get banned, VSS mod and fuel system
Sunday, November 19, 2006 2:09 AM
You're welcome Roofy. Keep in mind that when I originally posted that, HP Tuners was not available. Picking off the VSS is a band-aid solution. It "may" solve your problem, but the RIGHT way to do it is through the ECM. Get it reprogrammed and make it completely understand what you're throwing at it and you'll be in much better shape in the long run.






09:f9:11:02:9d:74:e3:5b:d8:41:56:c5:63

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