Dan, yes you can update your tranny to the vacuum modulated control. I'm not sure how involved it is, but it will save your clutches.

 

This is why I had Ed Wright set my line pressure to vary directly with my TPS. Patrick was the first one to bring this up, and I picked his brain a few times before getting the tuning done. <img src="gr_stretch.gif" border="0"> With the ported MAF ends, wouldn't the problem show up immediately if there is too little line pressure? I honestly don't know; that's why I ask.

 

Thanks Patric, I was looking at doing that when I bought the tranny, but didn't know what was involved. So I guess you need a tranny tricker for that setup as well? How do you controll shift points? Sorry for all the questions..

 

Patrick G - would it be better to run the Pace 85 mm screened LS6 calibrated MAF over the stock ported MAF to prevent the line pressure issue or is it going to create the same problem? TIA.

 

[quote]Originally posted by Kristi:
<strong>Funny, Trevor's car (same yr model) is MORE modded than mine and he's had ZERO codes or problems with his Vigilante 3200.

</strong><hr></blockquote>


thats just TOOOOOOOOOO funny.


I (heart) my Vigilante 3200.

 

Trevor, with ported MAF ends, the problems won't necessarily show up right away. The lower line pressure will take its toll on clutch linings over time, making the problems appear worse as the linings wear-in...or wear out.

Dan, if you upgrade to the vacuum controlled module, you won't need a tranny tricker as your pcm will still control shift points...just not line pressure.

TXCAMSS, a calibrated 85mm MAF should read the same load as a stock unported MAF, so this would help eliminate the line pressure issues. However, I found no hp gains (purely from an airflow standpoint) by swapping from a stock unported MAF to a calibrated screenless 85mm MAF in my 408 rwhp heads/cam LS1. Just food for thought.

 

Patrick,

I have an ST-3500 with ported MAF ends. For what I've done to the car, it runs like a beast. Under full throttle I get 28 degrees of timing with ported ends. With stock ends I usually get 2-3 degrees less timing. I do have a MAFT. I saw in another thread that you suggest tuning the fuel with the MAFT. Will this bump the timing back up? By tuning the MAFT to do basically the same thing that the ported ends do, won't it be just as hard on the tranny?

 

OK, basically unless my car is bone stock, down to the tires, I can't prove that the converter itself has a problem. He said it could be my MAF ends, if not them, then the shift kit, if not that, then my non-stock tires, if not those, then the cat-back exhaust, if not that, then the trans fluid... etc.

He said that one or all of these are causing my computer to get a torque reading that it sees as "incorrect" and it is therefore cutting the line pressure to the transmission. He says this is unique to the 2001 and 2002 model cars. According to him, my mods would be causing the car to do this even if I didn't have the converter, I just wouldn't feel it because it would be out of the stall range with a stock converter. In fact, he suggested that it's a GOOD thing I feel this because I'm not only buning my converter clutch up, I'm also destroying my transmission and at least now I know it! Who knew that gears, MAF ends, and a cat-back would destroy your transmission!?

When asked why I had 6 months and 6000 miles problem-free with the converter and am just NOW having trouble with NOTHING changed on the car, he said that the clutch is has just now "seated" and worn off the high spots and now that it's smoother, it's allowing the slippage. Hmmm...

I sure do hope the stock MAF ends fix it because other than that, unless I can set the car back to totally bone stock, I can't prove the converter itself is the problem and I'm just stuck with it.

On the tire size, I'm running the same size tires as an SS or WS6 so this implies that the SS and WS6 have different computer programming than a Z28 or V8 Firebird and I'm not sure, but I don't think that's quite right.

Funny, Trevor's car (same yr model) is MORE modded than mine and he's had ZERO codes or problems with his Vigilante 3200.

I'll try the MAF ends when I get home and report back.

 

Let us know how it goes. I'm sure glad that you didn't get the run-around. <img src="images/icons/rolleyes.gif" border="0"> I've been told more than once that it's the clutch material that's causing the shuttering, but I guess not. It's the 275/40/17's. <img src="graemlins/gr_bs.gif" border="0" alt="[bullshit]" /> My Vig 3200 has been perfect from day one, and you don't have to keep your car bone-stock to have one. <img src="gr_tounge.gif" border="0">

[ January 30, 2002: Message edited by: Trevor D ]</p>

 

I'm getting the same problems. I get shuddering on the highway when I'm accelerating. Never had this problem until last week.
I'm gonna wait till I change to my stock maf and replace the tranny filter and fluid. If that doesnt fix it, I'm giving Mike a call.

 

LOL, if that doesn't fix it, it's your headers... if not that, your pulleys. If not those, it's the CD you have in the CD player <img src="gr_images/icons/wink.gif" border="0">

Just kidding

 

[quote]Originally posted by mmiller:
<strong>By tuning the MAFT to do basically the same thing that the ported ends do, won't it be just as hard on the tranny?</strong><hr></blockquote>

I don't think so. As Patrick said, the ported ends make the computer think that there is less air, therefore less load, therefore reduced line pressure. With a MAFT you are adjusting how much fuel the computer is adding or subtracting, while the stock MAF ends are still reading the true amount of air coming through. So the computer will adjust load as you mess with your MAFT and line pressure shouldn't be effected.

Did I get that right Patrick? <img src="gr_stretch.gif" border="0">

later,
Steve

 

Here's some quick and dirty pics (sorry about the quality) of my vacuum modulator install I took.

You do have to drill one simple hole in the case,
and grind a little (its even in the instructions to do it) on the 1-2 accumulator housing. Anybody who can install a shift kit will have no problem.

Vacuum Modulator Install
Picture of vacuum modulator kit

Works great too.

<img src="graemlins/gr_cheers.gif" border="0" alt="[cheers]" />

 

"I don't think so. As Patrick said, the ported ends make the computer think that there is less air, therefore less load"

Yes, and that's the same thing you're doing with the MAFT which is why you get the same timing advance gains by leaning the mixture with a MAFT as you get by porting the MAF sensor.

[ January 31, 2002: Message edited by: Colonel ]</p>

 

Two things I've concluded after reading this thread:

1. Glad I went with the Vig3200 after wanting an ST3500 for 6 months.

2. Feel even better about removing my Maf ends and MAFT. Which didn't give me any more timing or rwhp... <img src="images/icons/confused.gif" border="0">

Good luck Kristy.

 

Well, the stock MAF ends are on and the PCM has been reset. My friend who works at a Chevy dealership drove it to work today and he said if anything, the problem is worse. This morning, their transmission guy (who's bar-none the most knowledgeable f-body mechanic in THIS neck of the woods) is changing the fluid/filter, then they're going to drive her around with TECH 2 and a line pressure gauge on her to see what's going on. If the line pressure is not dropping when the shudder/noise happens, it almost has to be an internal problem with the converter, I think.
I'll report back when I hear from them.

[ January 31, 2002: Message edited by: Kristi ]</p>

 

Rob, thanks for posting the Pic's. I think I'm going this route regardless which MAF ends I run.
Looks to be pretty simple to install to.

 

BTW, where did you get it?

 

Dan, re: vacuum modulator

Officially known as Transgo 46-MOD Vacuum Pressure Control System. Anybody who sells internal tranny hard and soft parts can get you one, although I got mine from Dana at www.pro-built.net as part of a complete rebuild kit.
<img src="graemlins/gr_cheers.gif" border="0" alt="[cheers]" /> <img src="graemlins/burnout.gif" border="0" alt="[Burnout]" />

 

Kristi & Loco, I have the same problem!!! I posted something a while back on the LS1.com board..with no response. I thought I was the only one that was experiencing this. I haven't posted it since because of fear I was gonna get bashed. Ya know the the high & mighty "YANK" converter. I called Mike and he told me the same thing to change the MAF end back to stock..I did and nothing! Same ****..still the same shudder as soon as it locks up after 45 mph and continues off & on up to 90..

So basically we should have our PCM's reprogrammed, change our ported MAF back to stock, perform other mods to fix this problem??? N-O! Alot of other people have converters and aren't having problems with them..I have 2 emails from other members off the LS1.com board that state they have the same problem..we need to talk to Mike as a GROUP & let him know there is something wrong with the ST3500's. I still have the e-mails and can send them to Mike.

PLEASE E-MAIL ME LETS GET SOMETHING ORGANIZED

[ January 31, 2002: Message edited by: SidewayZ-28 ]

[ January 31, 2002: Message edited by: SidewayZ-28 ]

[ January 31, 2002: Message edited by: SidewayZ-28 ]</p>