black318i Posted September 4, 2009 Share Posted September 4, 2009 Sometimes during WOT runs in 3rd or higher boost will suddenly drop from about 18 psi to about 12 and come right back up. It pretty much feels like hitting the rev limit except it's only one quick dip then back to normal. Usually it's at about 3k - 4k rpm and it happened at 5k once. I did a 20# pressure test and everything seems fine and it happens with my stock bypass and GFB BOV. I'm leaning toward tuning, but haven't been able to find anything wrong with my tune. What else should I check and what should I log. RPM, load, Manifold absolute pressure, WGDC, afr?? I will post some logs hopefully tomorrow. My setup is: Perrin crank pulley Perrin TMIC GFB BOV AVO DP 1mm pill OEM catless UP Here is my ROM http://www.box.net/shared/4eenfgfckk Link to comment Share on other sites More sharing options...
ShadowImg Posted September 4, 2009 Share Posted September 4, 2009 Sounds like what would happen if knock is detected. Link to comment Share on other sites More sharing options...
black318i Posted September 4, 2009 Author Share Posted September 4, 2009 Good call. I had a log with the issue, but unfortunately I can't find it. There is a knock event, but IIRC it looks to be from the sudden boost drop (Abrupt deceleration). I will definitely log knock sum though. Link to comment Share on other sites More sharing options...
ShadowImg Posted September 4, 2009 Share Posted September 4, 2009 Probably want to watch the ignition advance too -- if you suddenly see the dynamic drop, probably another good indicator. Link to comment Share on other sites More sharing options...
black318i Posted September 4, 2009 Author Share Posted September 4, 2009 Ok so RPM Load Manifold absolute pressure WGDC AFR Knock Sum & Ignition timing advance? What about Ignition total timing, would that be useful? Link to comment Share on other sites More sharing options...
black318i Posted September 5, 2009 Author Share Posted September 5, 2009 After several attempts I could not duplicate the problem which is unusual considering how many WOT runs I did. I guess I'll try again tomorrow. Link to comment Share on other sites More sharing options...
black318i Posted September 5, 2009 Author Share Posted September 5, 2009 Happened twice today. Here are the logs.romraiderlog_20090905_120127.csvromraiderlog_20090905_120039.csv Link to comment Share on other sites More sharing options...
05pearl Posted September 5, 2009 Share Posted September 5, 2009 I am thinking it's due to your tune (or maybe your bcs?), but I don't know enough to tell you. You may want to get this thread moved to the tuning forum. Link to comment Share on other sites More sharing options...
ShadowImg Posted September 5, 2009 Share Posted September 5, 2009 Agreed, looks like knock to my novice eyes -- you probably need a tune. You also probably want to stop doing that until you get one. Might want to send a PM to Infamous1, mickeyd, testes1010, etc and see if they can lend a hand. Link to comment Share on other sites More sharing options...
05pearl Posted September 5, 2009 Share Posted September 5, 2009 I did not see any knock. Knock sum stayed at 6 the entire wot throttle run. I am thinking it's either the boost in the tune or boost control solenoid. Link to comment Share on other sites More sharing options...
ShadowImg Posted September 5, 2009 Share Posted September 5, 2009 Look at feedback knock correction on the second log, right where boost drops out it goes from 0 to -3.87, and knock sum goes from 4 to 6. I'm guessing in the first log, which is actually the second log chronologically, the ECU had already learned and adjusted from the first. Link to comment Share on other sites More sharing options...
05pearl Posted September 5, 2009 Share Posted September 5, 2009 ^^ your right, i only looked at the first log. Link to comment Share on other sites More sharing options...
black318i Posted September 6, 2009 Author Share Posted September 6, 2009 Funny thing is nothing ever happened with fine learning and IAM never dropped. I know AF learning is off in this LV, but it was due to a leak which was fixed prior to these two runs. I forgot to reset the ecu after the repair. Normally it is only off by < 2. Also I will try to get this moved to the tuning section. Thanks for the input. Link to comment Share on other sites More sharing options...
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