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  1. #1
    Active Member Two Rings Alchemy's Avatar
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    Jan 14 2018
    AZ Member #
    412462
    Location
    North Carolina

    Mild hesitation under WOT before full boost.

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    Hey everyone,

    I just recently purchased my first B5 S4, & it's a properly done stage 3 at that ( well mostly).

    I'm having this slight hesitation when hammering the throttle. Anytime I apply a sharp transient in peddle pressure (read: step on it)
    the car hesitates before building boost but only for the first split second, after that it pulls righteously.

    This only happens when I initially go WOT, between gears it holds boost/power fine and nothing feels out of place.

    This really irks me because it makes the throttle feel disconnected. I know this is a DBW car, so my first inclinations where to clean the MAF & TB connections. Perhaps there is ever so slightly a boost leak?

    I have a basic enough knowledge to pull up parameters via VAGcom and monitor them if there are some leads I can chase down there.

    I guess this may also be in the tune (a custom tune which the car has been on for years).

    I'm not new to the b5 platform but I am to the 2.7t and boosted application for that matter so please bare with my ignorance

    Among other things I'm looking forward to straightening this issue out so that I can make the car feel 100%.

    -Josh
    2000 B5 S4 K04 Stg III - "Medusa"
    2004 V8 Touareg - "Kaiju"

  2. #2
    Registered Member One Ring
    Join Date
    Aug 27 2016
    AZ Member #
    379475
    Location
    Austin

    Similar symptom happened to me on various occasions.
    Check your hoses and clamps on your IC's. Could have developed a leak and under full boost the leak is showing up.
    My clamps where not sufficient and eventually replaced.
    Check to see if there is oil impeding airflow at the bottom of your IC's. Sometimes oil can pool right before the hose and under load could cause airflow issues.
    Worse case is a turbo is on its way out. Listen for a screaming or whistling sound when you feel the hesitation.
    Best of luck.

  3. #3
    Veteran Member Four Rings GOODBYNAAIR's Avatar
    Join Date
    Nov 17 2011
    AZ Member #
    84082
    My Garage
    1973 MG Midget, 2001.5 1.8T black.
    Location
    Fredneck Maryland

    Sounds like turbo lag?!
    My A4 Its For sale ---> GT2860 Project
    Tuning from Motoza
    B5 stuff FS
    PCV Dumped on my Driveway

  4. #4
    Veteran Member Four Rings
    Join Date
    Nov 04 2013
    AZ Member #
    128426
    My Garage
    stg 3 widebody, 1990 miata, '05 gsxr 1000
    Location
    Palo Alto, CA

    turbo lag doesn't exist, see dyno sheets. #alternativefacts

  5. #5
    Active Member Two Rings Alchemy's Avatar
    Join Date
    Jan 14 2018
    AZ Member #
    412462
    Location
    North Carolina

    Quote Originally Posted by GOODBYNAAIR View Post
    Sounds like turbo lag?!
    The more I analyze the way the carsdrives the more I think this is simply the case, the PO kind of planted the "hesitation" as an apparent issue so
    I may just be a total noob. I went for a 30 minute drive strictly to feel the car out and I'm leaning towards that fact that it simply takes a second for boost to build.

    I may still re tighten all my clamps just cause but according to the boost gauge I have strong vacuum and the boost builds linearly up till a 22psi spike holding at 20 till redline.


    Again, please excuse my ignorance, I am still getting a feel for running a boosted vehicle.
    I may also need to build a post count so I can post in the tech sub-forums ;)

    -Josh

    I'm used to torquey N/A set ups with snappy power so that's a factor.
    2000 B5 S4 K04 Stg III - "Medusa"
    2004 V8 Touareg - "Kaiju"

  6. #6
    Active Member Two Rings Alchemy's Avatar
    Join Date
    Jan 14 2018
    AZ Member #
    412462
    Location
    North Carolina

    Quote Originally Posted by 1st Trax View Post
    Similar symptom happened to me on various occasions.
    Check your hoses and clamps on your IC's. Could have developed a leak and under full boost the leak is showing up.
    My clamps where not sufficient and eventually replaced.
    Check to see if there is oil impeding airflow at the bottom of your IC's. Sometimes oil can pool right before the hose and under load could cause airflow issues.
    Worse case is a turbo is on its way out. Listen for a screaming or whistling sound when you feel the hesitation.
    Best of luck.

    I believe as what stated here, that I am simply not fully cognizant of what turbo lag feels like, the car is completely outfitted with a samco hose kit and the nice hardware, I've tested the hoses I can reach from the top without pulling the front clip and everything was snug.

    I'm confident the turbos are fine, in fact besides the LCD cluster and a bum rear view mirror this car is rock solid, for now.... lol


    -Josh
    2000 B5 S4 K04 Stg III - "Medusa"
    2004 V8 Touareg - "Kaiju"

  7. #7
    Established Member Two Rings Isaac313's Avatar
    Join Date
    Aug 15 2017
    AZ Member #
    405034
    My Garage
    2008 Ford F350 Diesel - 2000 Audi S4 - 1994 Ford F150 Lightning
    Location
    Michigan

    Quote Originally Posted by Alchemy View Post
    I believe as what stated here, that I am simply not fully cognizant of what turbo lag feels like, the car is completely outfitted with a samco hose kit and the nice hardware, I've tested the hoses I can reach from the top without pulling the front clip and everything was snug.

    I'm confident the turbos are fine, in fact besides the LCD cluster and a bum rear view mirror this car is rock solid, for now.... lol


    -Josh
    Depending on who tuned it, it might be that it's fueling a little too hard or not quite enough right as you get into it before boost comes on. Pre-boost fueling can be a little tricky. My buddies subaru (rip, long gone fortunately, was a pos), it would fuel so hard before boost came on that if you tried hard enough, it would smoke like a diesel almost. but then the GT28 came on hard.

    Seems like you're more used to NA, but maybe your tune isn't quite the way you like it, wouldn't be too expensive to try another option and see how that is. A little tuning goes a long way.

  8. #8
    Active Member Two Rings
    Join Date
    Jan 29 2014
    AZ Member #
    141500
    My Garage
    b5 s4 avant stg 3 f21 e85
    Location
    Broomfield

    Turn your esp off. See if that helps

  9. #9
    Active Member Two Rings Alchemy's Avatar
    Join Date
    Jan 14 2018
    AZ Member #
    412462
    Location
    North Carolina

    Quote Originally Posted by Isaac313 View Post
    Depending on who tuned it, it might be that it's fueling a little too hard or not quite enough right as you get into it before boost comes on. Pre-boost fueling can be a little tricky. My buddies subaru (rip, long gone fortunately, was a pos), it would fuel so hard before boost came on that if you tried hard enough, it would smoke like a diesel almost. but then the GT28 came on hard.

    Seems like you're more used to NA, but maybe your tune isn't quite the way you like it, wouldn't be too expensive to try another option and see how that is. A little tuning goes a long way.

    I think you have the right idea, I'm probably going to have the car tuned again once I'm back home this summer. I have a dyno from a few years back showing a table like tq cruve coming on strong at 3k but when I'm hitting it at 3k the love isn't there like I'm wanting.

    The next question, what are my options for reputable tuning in the southeast? I'm local to Wilmington, NC.


    Quote Originally Posted by Hulksmash View Post
    Turn your esp off. See if that helps
    There is no ESP button on this b5. Is this something I need to access in the ECU?

    -Josh
    2000 B5 S4 K04 Stg III - "Medusa"
    2004 V8 Touareg - "Kaiju"

  10. #10
    Registered Member One Ring
    Join Date
    Aug 27 2016
    AZ Member #
    379475
    Location
    Austin

    There are 3 buttons to the left of you hazard button. front driving, rear driving and ESP disable. You will habitually turn it off eventually. It could definitely cause a retardation of boost under heavy throttle.

  11. #11
    Established Member Two Rings Isaac313's Avatar
    Join Date
    Aug 15 2017
    AZ Member #
    405034
    My Garage
    2008 Ford F350 Diesel - 2000 Audi S4 - 1994 Ford F150 Lightning
    Location
    Michigan

    Quote Originally Posted by Alchemy View Post
    I think you have the right idea, I'm probably going to have the car tuned again once I'm back home this summer. I have a dyno from a few years back showing a table like tq cruve coming on strong at 3k but when I'm hitting it at 3k the love isn't there like I'm wanting.

    The next question, what are my options for reputable tuning in the southeast? I'm local to Wilmington, NC.




    There is no ESP button on this b5. Is this something I need to access in the ECU?

    -Josh
    Your car is a 2000 and doens't come with ESP. ESP is just Electronic Stability Program. Basically a traction control of sorts. I like it ok when I'm not driving aggressively or anything but it's usually turned off. My personal car is also a 2000 and doesn't have ESP and i don't really miss it. It's fine.

    I doubt even if you had ESP, it would cause your issue, I'd probably look into tuning.

    There are a few members on here that have good tuning reputations. My car was tuned by Blake at ETSpec. I'm assuming he'll do big turbo stuff too, mines just KO3's though.



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