VMP Twin 72mm Throttle Body Issues

RRRR03Cobra

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Last month, I installed the new VMP Gen 2 Supercharger and a 2.4 upper,a L&M Twin 72mm tb, Steeda 130mm CAI, 2014 Shelby Injectors and a high flow H pipe. I took and had the car tuned a couple of weeks ago. All of the numbers were where I expected them. On the way home from the dyno, I noticed the car seemed to surge at low throttle and the drivability was terrible. I asked my tuner about it and he stated that it was probably the L&M. So I changed it out with a FRSCJ Twin 65mm throttle body. The car ran great with this throttle body but I know it doesn't flow no where near the twin 72. So when VMP released the twin 72mm, I couldn't wait to get it. I installed it a couple of days ago and drove to work yesterday. Man was I disappointed! All of the symptoms returned. The surging at low throttle, the idle sticking above normal etc...
My tuner sent me 2 tunes to try and correct the problem with no avail. I don't understand it! Has anyone had these symptoms? How did you correct it? I would really like to keep the VMP TB due to the size and maximum airflow, but driving the car just sucks! Thanks SVTP family!
 

Willie

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Surging at low rpm's is a result of reversion when the TB is too large. It CAN be tuned out, but not always. The problem is there are almost an infinite number of parameters that can affect this and tuners will not spend the time "guessing", for obvious reasons.

I tune myself and have the 72mm L&M. I was able to tune most of the surging out (not all) but it took many, many iterations to get it to where I can't complain.
 

Willie

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Our cars are supposed to be identical, but the simple truth is, no two cars are. I own a pair of 2008 GT500's, so I would think tuning both would be like tuning one but it is not. The 72mm L&M I'm referring to above is on one of my two cars. I recently removed it because I am selling that car (#1). Then for giggles, I installed it on #2. What a surprise.... It ran great and required no other changes.... So I kept it and sold the 65mm CJ I had on it.
 

RRRR03Cobra

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Thanks for info guys. I talked to my tuner again and he sent me another tune this afternoon . I downloaded into the car and presto !! She runs perfect ! I will have to say the VMP pulls alot harder than the Cobra Jet did! It breaks loose in upper 3rd gear now! Love it!!
 

Willie

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Can you do me a favor? Ask your tuner which of these parameters he changed. I'm very curious...
or if it was something else....
Dashpot Advantage.jpg
 

DaFreak

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Willie,

Wondering, I know these "tunes" are just config files for our cars. Do you have a tool or know of a way to diff 2 tune files to see what changed?

Curious,
DF
 

Willie

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I use SCT's software. It's called Advantage III or "Mako". Within it, you can load multiple tune files concurrently, then run a "compare" feature. Not only does it list the parameter that's different, but all the values too.

But please keep in mind that the files must be in .mtf format. These files can be loaded into Mako. If you receive tune files via e-mail, the tuner will send it to you in .cef format, which is unreadable by Mako, or anything else for that matter. And to be brutally honest, tuners who make a living doing this will NEVER share .mtf files because it will reveal all their "secrets".
 

Catmonkey

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Unless you've gone through SCT training, SCT does not make some of the DBW and throttle body maps accessible to PRP users.
 

Willie

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Unless you've gone through SCT training, SCT does not make some of the DBW and throttle body maps accessible to PRP users.

That was my impression too but I found out that this is not true. I contacted SCT and was given "calibrator" level, which is the highest level and allows me to view and change everything. At the time of my request, I was "warned" about some of the dangers involved. I do not have SCT training but I have years of hands-on experience and I haven't killed myself yet.. LOL.. I'm speculating here but I have had the software for over eight years. Maybe there is a minimum before they allow full access.....
 

rotor_powerd

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Full control over throttle/drive by wire parameters are obviously the most dangerous parts of the calibration, as far as SCT and lawsuits are concerned. I'm surprised they would unlock that for an end user without first going through their classes.
 

tones_RS3

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Glad you got the issue resolved and can enjoy your car fully again.
VMP Performance makes and have some killer products/tunes.
 

Willie

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Full control over throttle/drive by wire parameters are obviously the most dangerous parts of the calibration, as far as SCT and lawsuits are concerned. I'm surprised they would unlock that for an end user without first going through their classes.

Agreed. Even before given full access, my practice has and always will be, to never change any parameters I am unfamiliar with unless I talk to a full-time tuner. I may not be the smartest guy here, but I'm certainly not the dumbest..!
 

VNMOUS1

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My Twin Jet 72mm failsafed like a mofo with a normal 65mm file on board. Took a little tweaking and bam!

So, it's a calibration issue. You can have your tuner call us. Vmpperformance.com

Sent from my SM-G935V using Tapatalk
 

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