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Discussion Starter · #1 ·
I have tried sooo many combinations and none of them work. mbc before N75F/J, mbc after N75f/j ( I just get big spikes (15psi) then it settles back to 10psi.
Running the mbc alone set to 13psi works great for a little while then I get soft limp mode on and off. It does this even if I set the mbc to 11psi.
Unplugging the N75 seems to cause immediate limp too. Seems to me that a mbc isn't going to cooperate with the 2003 AWP engine.. Unless perhaps I clamp the MAP signal? Not too sure I want to do that yet....
Any info here would be appreciated!



Modified by SnowGTI2003 at 4:20 AM 1-8-2004
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (SnowGTI2003)

Funny you should ask!
I just installed a "BoostValve" Tonight!
I installed it in the "N75 ByPass Mode".
At 1st, I guess I didn't have it cranked-down enough, cause it would go-upto 1.5bar,
settle-down to 1bar for a few seconds, then suddenly plummit to .5bar!
Then I cranked on it some-more, took it for another drive, and this time it seems to be holding at around 1-1.5bar,
and accelerating faster than it has in a while!
And all my surging seems to have disapeared!!
Please take this with a grain of salt, because this is extremely preliminary!
P.S. Go Coyotes!! http://****************.com/smile/emthup.gif



Modified by exS4 at 4:34 AM 1-8-2004
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (exS4)

I'm just using the stock programming and trying to get a few more psi. I know it will be safe as long as I stay below 1 bar... But the ECU seems to get smart and realize the N75 is gone after 15 - 20 mins of driving.
oh... and I've using the boostvalve mbc too.
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (SnowGTI2003)

I don't claim to be an expert, but I think you are right in that, if you try to boost above the
ECU's requested boost for more than a few seconds, as I undestand it, you WILL go into Limp mode. In MY case, as I'm sure you have already realized, I have an aftermarket TurboKit, which includes performance-oriented programming. So perhaps I have more lee-way to play than if I still was running the stock ecu. I believe stock boost is supposed to max-out at something like 11lbs. Therefore it makes sense that since you have been setting your boostvalve to higher than that, you are oftentimes getting into Limpmode unfortunately.
In which case, the only way around that other than a chip or standalone is a diode...


Modified by exS4 at 4:56 AM 1-8-2004
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (SnowGTI2003)

"But the ECU seems to get smart and realize the N75 is gone after 15 - 20 mins of driving."
Are you keeping your N75 electrically connected?
If You disconnect the harness you WILL get codes etc.
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (exS4)

Yeah I'm keeping the N75 electrically connected.
It seems that it takes about 15 minutes of driving to start to upset the ECU. Before that everything runs just great with the mbc, but after that I just hit limp mode continuously.
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (SnowGTI2003)

Running a mbc on stock programming doesn't seem to work well. Stock programming simply doesn't play nice with increased boost. Plus, increasing boost on stock programming is a potentially dangerous experiment.
A MBC mixed with chipped programming can be great though. I myself use APR DPP 93, an N75 'J' valve, and a MBC running in parallel to the 'J' valve to clip off the initial tall boost spike. I have tried all the N75 valves and all kidns of different combinations, and for me this works great. Some very noticable extra kick over just the chip, and a very smooth feel.
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (LeChefJosh)

Quote, originally posted by LeChefJosh »
Running a mbc on stock programming doesn't seem to work well.

Works fine for me and AERacing. Some cars are picky.
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (SnowGTI2003)

"Yeah I'm keeping the N75 electrically connected.
It seems that it takes about 15 minutes of driving to start to upset the ECU. Before that everything runs just great with the mbc, but after that I just hit limp mode continuously"
Maybe your boostgauge(assuming you have one) is off by a few lbs.
So when the gauge says you are at 11 lbs. maybe you are really at 12-14 lbs.
which could possible throw you into Limp mode.(Just guessing!)



Modified by exS4 at 2:49 PM 1-8-2004
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (AERacing)

we have this set up on my girls car and havnt have a problem spikes to 18-19 psi and 10-11 by red line. http://****************.com/smile/emthup.gif
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (AERacing)

Hey I'm Silverstone grey too!
My boost gauge seems to be calibrated correctly... With the stock N75 F valve I get 12 psi spikes and hold 10psi. Now that I've been thinking about this (and reading the 'Anatomy of limp mode) post I think it may have to do with the fact that it's -12 C outside right now... and the cars have a tendency to limp easier in cold weather. Shoot me down if this makes no sense!
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (VDUBNDizzy)

Quote, originally posted by VDUBNDizzy »

Works fine for me and AERacing. Some cars are picky.

I guess I should clairify my statement. You can pretty easily get a MBC to work with the car as a replacement or supplement for the N75 valve, but it seems most people have poor luck using an MBC to gain more power out of the car (ie: upping the boost past stock levels).
So if you're trying to cure surging, a MBC might be the thing for you. If you're looking to crank up the boost on stock programming, you might end up with some problems.
And all problems are not noticable by simply driving the car
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (SnowGTI2003)

i haven't read all the other posts, but heres my experience: at first my MBC was great. now i hit limp all the time. its never at WOT either, its just daily driving that gets me...i looked at vag stuff while changing from 1st to second and going to about half throttle and saw the car request some low boost around 7 but the k03 spools and the MBC lets it make full boost, so it threw an overboost code...makes me think that a clamp would have to be set low...
edit: i started hitting the limps with this cold snap...


Modified by gelatin at 8:33 AM 1-8-2004
 

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Re: WHo is actually successfully running a mbc on a 2003 AWP? (SnowGTI2003)

"Now that I've been thinking about this (and reading the 'Anatomy of limp mode) post I think it may have to do with the fact that it's -12 C outside right now... and the cars have a tendency to limp easier in cold weather. Shoot me down if this makes no sense!"
That sounds like a reasonable conclusion to me...
 
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