Jump to content

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)
cburke996

Boost isn't very smooth, occational overboost

Recommended Posts

Hey guys, I'm trying to figure out an issue in my TT. Boost delivery isn't as smooth as it used to be. Under constant throttle application (lets say half throttle) boost will hold at .4bar for a number of seconds when it should really be building up, and then all of a sudden it jumps up to 1.2bar and takes off. Occationally it will jump up to 1.5 bar and hold until I let off (I don't hold it for long, and I try to avoid this). I've got an EPL K16 flash set for 1.2 bar, so 1.5 is overboosting. And then, sometimes I just can't get up to the 1.2 bar...it will max out at .8-.9 occationally.

So far I checked the hoses at the N75 valve, they look ok. I found a big crack in the Y-hose, that plugs into the bottom of the DV's. I replaced that hose, and still have unsmooth boost delivery. What else might be the culprit here? Maybe the N75 valve is on its way out? Sticky wastegate actuators? I haven't gone underneath to investigate them. Any help is appreciated.

Thanks,

Connor

Share this post


Link to post
Share on other sites

There are several things that can cause weird boost profiles, including those you already mentioned. I may also be related to your re flash software as well. I'm afraid there probably is not a quick answer for this one, it is going to take some diagnostics time to check out all the components one at a time to see where the problems lies.

Share this post


Link to post
Share on other sites

As I posted elsewhere, my guess would be a leak somewhere in your system. Do a pressure check. It could be DVs themselves or waste gates. I doubt it's the flash, but the flash does mean you are putting more stress on the system perhaps.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Similar Content

    • By OscarAH1W
      Transitioning from previous thread to new one--  Replaced the water pump and performed the 60,000 mile service in my 04 Turbo Cab.  Car runs great except now I am getting overboost to 1.0-1.3 bar.  I don't hold it there to be sure.  That said, I realize it is likely a vacuum issue but the only lines I touched during the repair are the one from the Y-Pipe to the switch and the one from the switch to the plastic line that goes to the driver side of the engine.  Flashlight and inspection mirror show the 3rd line on the underside of the switch to be connected.  Any thoughts on where else to look?
       
      Thanks
       
      Owen
    • By lewisweller
      Err well here it is the first code to pop on the problematic ctt P0234 overboost. Was driving to today and booted it a bit and felt flat to redline Wtf, almost like the variocam didn't switch to high lift because the boost gauge said +0.8 bar still as per spec. So I whipped out the trusty v-checker which is always in the temperamental Pig in case, and it shows the P0234 code. 
      I know the possible causes and have read a lot of posts of this code but not found any with fixes except loose piping broken piping which at the moment I'm thinking I don't have any (all bloody new). N75 valve is new, MAP sensor is original but I've cleaned it today and before it didn't make any difference then or now. Turbo problem possible but unlikely I think. So what does that leave?  
       
      If I clear codes it won't return in short run but did after many Km today return and cleared again. 
       
      No here is the only interesting thing about it, when the code is active it goes into a limp mode flat performance and the stutter hesitation I suffer with since I got the car goes away and it drive smooth but slower of course. I clear the code and get boost back but also the kangaroo stutter stammer acceleration. 
       
      If I disconnect the map sensor exactly same result but a difference code like P???? Underboost which makes sense. 
       
      So guys what makes a turbo engine do this? 

    • By GSpence2
      Just for fun. Recently had my 120k mile service completed for my 04 CTT. Clean bill of health and ran good sounded better felt great. Soon there after I happened across a gent in a Viper truck, coming up behind me fast flashing his lights blowing his horn and then pulls along side window down and thumbs up. I think to myself, " ...man I too old for this sh*t...", but give him a go anyway. PSM off, suspension lowered and to sport, 3 horn blasts and floor it! After a huge breath and accompanying roar and turbo lag, it's 1st gear and off we go! Needless to say it was fun. More to say after he caught up; "...that's not stock!" No it isn't I reply. So as I let him speed of I continue my leisurely sub 60mph drive home. Along the way I get PSM failure visit workshop. Okay...next up check engine light. Hmm...next up tranny lights up like it's in safe mode but is audibly and physically shifting fine. Temp is a little higher than normal and hmm...no more than .3 bar boost at WOT? Okay what did I break now? SO, at home codes pulled: 2187, 2198, 2281, 0299.
      Okay smoke 'em! Turn out I've manage to "break?" the old worn out breather hoses and the intake distributor is leaking! Gee Bevis...anywho fun weekend for me! So, while I'm in there I think I'll swap out the diverter valves and control lines as well. Just wanted to share.








    • By bennyx
      Hi.
      Please watch the video and see if the boost is doing what it should. Video is taken from standstill in 1st gear, full throttle, up to third gear.trim.Dq9a7e.MOV
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.