MTBwrench Posted June 9, 2017 Share Posted June 9, 2017 Yikes do no boost! you have a big leak. What did you do? Plug the intake, and blow into the BPV return hose and close with ur finger and you'll hear the leak, although this sounds like a big leak so it may not even pressurize. If anything, a boost leak would make it run rich... not lean. OK, do you have a way of checking your fuel trims? That could be helpful. Also, how old are the MAF and frtont O2? Sent from my SM-G950U using Tapatalk MTBwrench's Stage 3 5EAT #racewagon 266awhp/255awtq @17.5psi, Tuned By Graham of Boosted Performance Everyone knows what I taste like. Link to comment Share on other sites More sharing options...
Baggedlgt Posted June 9, 2017 Share Posted June 9, 2017 If anything, a boost leak would make it run rich... not lean. OK, do you have a way of checking your fuel trims? That could be helpful. Also, how old are the MAF and frtont O2? Sent from my SM-G950U using Tapatalk Maf replaced and o2 is only about 7 months old. About to replace my fuel pump tho and see if that helps. How would a boost leak make it run rich? It would make it run lean Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Th3Franz Posted June 12, 2017 Share Posted June 12, 2017 Maf replaced and o2 is only about 7 months old. About to replace my fuel pump tho and see if that helps. How would a boost leak make it run rich? It would make it run lean Sent from my iPhone using Tapatalk Stock intake? Check for pre turbo leaks or torn turbo inlet -Franz The end of a Legacy http://www.youtube.com/th3franz Link to comment Share on other sites More sharing options...
Baggedlgt Posted June 13, 2017 Share Posted June 13, 2017 Was in k&n typhoon but thought that was the reason so put stock back on still same issue Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
08Legacy-GT Posted June 13, 2017 Share Posted June 13, 2017 If anything, a boost leak would make it run rich... not lean. OK, do you have a way of checking your fuel trims? That could be helpful. Also, how old are the MAF and frtont O2? Sent from my SM-G950U using Tapatalk Depending on where it is.. it can go both ways 2017 Subaru STI 2008 Subaru Legacy 2.5i limited Link to comment Share on other sites More sharing options...
MTBwrench Posted June 13, 2017 Share Posted June 13, 2017 Maf replaced and o2 is only about 7 months old. About to replace my fuel pump tho and see if that helps. How would a boost leak make it run rich? It would make it run lean Sent from my iPhone using Tapatalk Depending on where it is.. it can go both ways Perhaps I'm wrong on this... but a boost leak means less pressure (aka- volume) of air making it into the engine. I always assumed with the way everything works in open loop operation that this would simply cause a rich situation due to the excess fuel being fed to the engine. Or does it still read MAP and calculate IDC from that? Sent from my SM-G950U using Tapatalk MTBwrench's Stage 3 5EAT #racewagon 266awhp/255awtq @17.5psi, Tuned By Graham of Boosted Performance Everyone knows what I taste like. Link to comment Share on other sites More sharing options...
08Legacy-GT Posted June 13, 2017 Share Posted June 13, 2017 What happens when there's a leak and there's more pressure? i.g. more air getting in between maf sensor and turbo? 2017 Subaru STI 2008 Subaru Legacy 2.5i limited Link to comment Share on other sites More sharing options...
Baggedlgt Posted June 13, 2017 Share Posted June 13, 2017 I've been looking this thing over like crazy. Even put my stock bov back on and still issues only on cobb maps. I honestly think it's a bad tune. They claim it's cuz I'm running catless and the tune is for high flow but I've ran this pretty much same catless exhaust setup on my 04wrx and friends too. Never had a problem especially running this lean on their maps The only thing that I'm wondering is the car sat for a whole year and recently was started up but I've been through probably 2 tanks of 93 Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
covertrussian Posted June 17, 2017 Share Posted June 17, 2017 Just wanted to say thanks to Th3Franz and MTBwrench. Between last year and this year I noticed that I was getting leaner and leaner. I compensated by adding fuel in the fuel map at full throttle, but noticed that my ABC learning was at almost +10. I would go into open loop and car would lean out, similar to closed loop delay (which is fully disabled). I had to add 11% to MAF table to get that ABC learning back down to be in in sub 5% (though negative this time). Anyway, pulled my fuel filter bypass fuel pump assembly. I've suspected a line having a slow leak, but since fuel pressure didn't drop when car was turned off I didn't think about it. Well installed stock fuel pump assembly and it's on the same tune now it's about 0.5 AFR's too rich. So thank you guys for helping me find the real culprit instead of using the tune to hide the issue. 05 LGT 16G 14psi 290whp/30mpg (SOLD) 12 OBP Stock 130whp/27mpg@87 Oct 00 G20t GT28r 10psi 250whp/36mpg 22 Ascent STOCK Link to comment Share on other sites More sharing options...
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