Chern889 Posted April 8, 2015 Share Posted April 8, 2015 Been trying to diagnose and fix a high AF correction at idle and slow cruising. Everything I've read says its a pre-turbo air leak, I've gone through every hose and connection, fixing a few things. Air tight now via boost leak test(no smoke test though). At warm idle I will see as high as 9%. Seems to vary a lot with outside temperature, with cold being more stable, hot is all over the place. Also seeing occasional FBKC sometimes as high as -8.0 at random times. I always run 94oct fuel from the same station. Anyone have any input? Recent work includes: Brand new genuine MAF sensor and front O2 sensor. Replaced intake o-rings and gaskets Removed, cleaned and inspected turbo inlet Checked/zip Ty every hose while intake was off Cleaned PCV system/replaced PCV valve Replaced EVAP valve under intake Re-wired fuel pump with 12ga wire Replaced/re routed a pinched fuel line on intake Sea foamed engine through bpv hose Verified correct fuel pressure Modifications to car include: Accessport V3 running Cobb OTS stg 2 91oct map Catless UP Catless DP AVO TMIC Perrin AFTA-MAF Airbox lower air-horn removed(previous owner, don't have it) Had a Perrin panel filter, switched to an AVO panel but made the correction skyrocket to +25%, so went to a wix paper filter, just waiting on dealer to get more factory filters in stock and going to try that next. Sorry for the novel. Working on an e-tune with a reputable vendor but cannot continue until I get this nailed down. Totally out of ideas. Edit: Forgot to mention the car is an 05 LGT with the 5EAT, currently at 188,000km http://i124.photobucket.com/albums/p38/chern_889/Mobile%20Uploads/image_zpsviqdbnrg.jpg Link to comment Share on other sites More sharing options...
spec.B Dream Posted April 8, 2015 Share Posted April 8, 2015 Stock injectors? Link to comment Share on other sites More sharing options...
Chern889 Posted April 8, 2015 Author Share Posted April 8, 2015 Yes stock injectors Link to comment Share on other sites More sharing options...
spec.B Dream Posted April 8, 2015 Share Posted April 8, 2015 So, stock intake (essentially), stock injectors, and running lean at idle requiring additional fuel correction. No correction at higher loads/rpm? Are you absolutely sure there are no leaks? There are a ton of vac/boost lines on these engines that are easy to lose track of. Since your concern is low load/idle and you don't have a ton of mods, have you tried flashing back to stock and seeing if the correction problems are still there? There could be a problem with your current tune. Other mechanical causes: Air leak (intake or exhaust pre- front O2 sensor) Dirty/broken injector Dying fuel pump (but pressure is OK) ??? Link to comment Share on other sites More sharing options...
Chern889 Posted April 8, 2015 Author Share Posted April 8, 2015 Could a pre sensor exhaust leak cause that much trouble? I do have a leak somewhere pre turbo that I noticed while sea foaming(smokin like a bitch up the engine compartment) Link to comment Share on other sites More sharing options...
Scubaru03 Posted April 9, 2015 Share Posted April 9, 2015 Yes it can your up stream O2 is not able to monitor the gas properly so it thinks your lean. I would start with fixing those leaks. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
pseank Posted April 9, 2015 Share Posted April 9, 2015 I second that. Fix exhaust leak. Front o2 is really an air/ fuel lambda sensor and is CRITICAL. Link to comment Share on other sites More sharing options...
Chern889 Posted April 13, 2015 Author Share Posted April 13, 2015 I did some poking around today and found my leak at the crosspipe on the pass side. The previous owner installed the up pipe right before I bought the car, looks like he reused the original gaskets. Will have to order up a set of Grimmspeed gaskets and redo everything. Hopefully it fixes my issue, it doesn't seems like it's leaking very much, but maybe it's enough? Link to comment Share on other sites More sharing options...
compsurge Posted April 13, 2015 Share Posted April 13, 2015 AF #1 could be as very small. If you look at the metered air amount, you'll see how little of a hole it takes. Link to comment Share on other sites More sharing options...
joeleodee Posted April 13, 2015 Share Posted April 13, 2015 Stock gaskets from your local dealer work fine. Link to comment Share on other sites More sharing options...
pseank Posted April 14, 2015 Share Posted April 14, 2015 I used stock and they were fine as well! Link to comment Share on other sites More sharing options...
oncesir Posted April 25, 2015 Share Posted April 25, 2015 Interested to know if this fixed your issues as I have a similar reading and have also smoke tested etc. Link to comment Share on other sites More sharing options...
Chern889 Posted April 25, 2015 Author Share Posted April 25, 2015 I haven't replaced any exhaust gaskets, but in the last 2 weeks the "AF Learning 1" hasn't gone over 1.90%, so now I don't know what to think, it seems very temperamental? Link to comment Share on other sites More sharing options...
oncesir Posted April 25, 2015 Share Posted April 25, 2015 I haven't replaced any exhaust gaskets, but in the last 2 weeks the "AF Learning 1" hasn't gone over 1.90%, so now I don't know what to think, it seems very temperamental? Mine is the same way. It went down to 4% last week and now it's up to 11% today. Good luck finding your issue. I'm concerned it's the Cobb ots tune. Link to comment Share on other sites More sharing options...
oncesir Posted April 28, 2015 Share Posted April 28, 2015 Well hopefully this helps someone else including the OP. I smoke tested my exhaust today and found a questionable crossover pipe gasket. It doesn't even look like a gasket. It looks like a piece of metal cut to fit. I bought the car with the catless up pipe installed so this is my next replacement item. Wish me luck. Link to comment Share on other sites More sharing options...
oncesir Posted May 6, 2015 Share Posted May 6, 2015 I replaced all the gaskets in question and still have the same issue. I'll be building an intake pressure tester next. Dammit this is pissing me off. Link to comment Share on other sites More sharing options...
vr4gt_2_Legacy Posted August 4, 2016 Share Posted August 4, 2016 Did you ever resolve this shit? Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.