Bostonian1976 Posted September 3, 2015 Share Posted September 3, 2015 Hey all, I'm becoming obsessed with my fuel trims. My LTFT at idle is 10.2, and usually around 11 at cruising speed. This, to me, tells me I don't have a vacuum leak. So far I've: - cleaned the MAF - replaced front 02 sensor - replaced my PCV (what a job that was!) - had my dealer do a smoke test for intake leaks - none, according to them - checked my airbox - it's sealed - replaced my MAF O ring What next? one big question I have - when I removed the intercooler, there were no O rings between the turbo and intercooler, nor between the other thing (blow-off valve?) on the other side of the intercooler. Should there be O rings here? Could that cause my issue? My hose from throttle body to intercooler also has a small crack ABOVE the clamp. No cracks that I can see within the area that air actually flows that I coul see. The donut on the inside looked strange to me though. I'm going to run a bottle of Royal Purple fuel system cleaner through to hopefully help any fuel delivery issues. My 'fuel rail pressure' through DashCommand OBD is between 4-6. Not sure if that's accurate? the car MOVES when I floor it, so I can't imagine I have a big fuel delivery issue. Anyway - help. I've spent a ton of hours on this, my hands are cut up from the PCV job, and I'm getting frustrated Link to comment Share on other sites More sharing options...
Max Capacity Posted September 3, 2015 Share Posted September 3, 2015 Yes there should be o-ring seals. Fix that. A chevy thermostat gasket will work at the inlet to the tmic. Donut... what's that. Is that the rubber boot we all remove ? 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Bostonian1976 Posted September 3, 2015 Author Share Posted September 3, 2015 Yes there should be o-ring seals. Fix that. A chevy thermostat gasket will work at the inlet to the tmic. Donut... what's that. Is that the rubber boot we all remove ? Thanks! Maybe...it's the slimy silicone thing that folds inward. Could those O-rings be causing my whole issue? Also, which thermostat gasket? There seem to be many available Link to comment Share on other sites More sharing options...
Max Capacity Posted September 3, 2015 Share Posted September 3, 2015 http://legacygt.com/forums/showthread.php/rootbeers-cheapo-slow-poke-build-thread-228748p12.html see post #471 the BOV o ring may come from an auto parts store or the dealer. You don't want any leaks in that system, I'm no expert about what he effects are from those leaks. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Bostonian1976 Posted September 4, 2015 Author Share Posted September 4, 2015 thank you for the help here. How can i determine if the MAF is bad? I tried the 'unplug it while running' trick, and the car immediately died. Does that mean my MAF is good, or could it still be causing the lean issue? Lean is consistent across all revs. Cruising speed, idle, etc. 10.2-11.2 LTFT Link to comment Share on other sites More sharing options...
MAP Posted September 4, 2015 Share Posted September 4, 2015 Are you getting a lean trouble code? Link to comment Share on other sites More sharing options...
Bostonian1976 Posted September 4, 2015 Author Share Posted September 4, 2015 No, no code - but I think that takes something like +25 to throw a code right? I'm at 10.2-11, sometimes 12. That's no good for an XT, right? Link to comment Share on other sites More sharing options...
MAP Posted September 4, 2015 Share Posted September 4, 2015 Could you take a picture of the intercooler inlet? How could you get any boost without an o ring there? Link to comment Share on other sites More sharing options...
Underdog Posted September 4, 2015 Share Posted September 4, 2015 Anything within +/-15 is within the ECUs ability to compensate and doesn't represent a problem in itself. The fact that you are +11-12 in all four ranges could suggest a fuel pressure problem, dirty injectors, post-MAF leak, bad MAF, etc., but the ECU is able to operate the engine normally due to the leve of correction required. A leak at the turbo/TMIC flange or BPV flange could certainly cause the ECU to add fuel, and may not show up in a manifold smoke test, depending on how it is performed. The Crimson Dynamo Link to comment Share on other sites More sharing options...
Bostonian1976 Posted September 4, 2015 Author Share Posted September 4, 2015 Could you take a picture of the intercooler inlet? How could you get any boost without an o ring there? sorry - should have adjusted this. put a new gasket in last night, and found the O ring WAS in there - just was stuck. So, that wasn't the issue. But I have a shiny new gasket Good to know that the engine can run as normal with these fuel trims - I didn't know that Link to comment Share on other sites More sharing options...
xt2005bonbon Posted September 4, 2015 Share Posted September 4, 2015 Do you have a friend that would let you borrow his working MAF? If yes, you could put that in and see how the car behaves with a different MAF. Link to comment Share on other sites More sharing options...
Bostonian1976 Posted September 4, 2015 Author Share Posted September 4, 2015 Do you have a friend that would let you borrow his working MAF? If yes, you could put that in and see how the car behaves with a different MAF. unfortunately no Could this be the cause? would a bad MAF mean consistently high LTFT across all RPM range and speed (except deceleration - I don't have it at deceleration) Link to comment Share on other sites More sharing options...
xt2005bonbon Posted September 4, 2015 Share Posted September 4, 2015 I am not sure. I just feel that a bad MAF can cause all kinds of issues. So I would rule that out first. Link to comment Share on other sites More sharing options...
Underdog Posted September 4, 2015 Share Posted September 4, 2015 Bad MAF could definitely cause these issues, cleaning may not help, and MAFs are generally "consumable" on these cars. Even troubleshooting via the diagnostic process will not condemn a bad MAF sometimes. Recommend swapping with a known good one first, and replacing only if trims come back closer to zero. Again, as long as you aren't pegged + or -15 then the ECU is doing its job to work around whatever problem may or may not exist. Still good to make sure everything is running right though. The Crimson Dynamo Link to comment Share on other sites More sharing options...
Bostonian1976 Posted September 4, 2015 Author Share Posted September 4, 2015 ok thanks. I may just bite the bullet and buy a new MAF. Is that a mistake? Link to comment Share on other sites More sharing options...
Underdog Posted September 4, 2015 Share Posted September 4, 2015 Only if you don't mind "throwing $$$ away" if it turns out not to be the culprit. The MAF isn't cheap. The Crimson Dynamo Link to comment Share on other sites More sharing options...
MAP Posted September 4, 2015 Share Posted September 4, 2015 If the engine has no other symptoms other than higher LTFT the fuel injectors might be a little dirty. I had good results with a Redline fuel injector cleaning product early this year when I had a lean condition that set a code. I first ran some techron cleaner at 1.5x the recommended concentration and it provided a significant difference within a quarter tank. After another tank of regular gas the code returned. I then tried the Redline stuff and the problem hasnt come back since. Try the techron stuff first. If you notice a decrease in trim then you know its just the injectors that need cleaning. This is the first car I've ever had that had a lean code due to dirty injectors. Link to comment Share on other sites More sharing options...
Bostonian1976 Posted September 4, 2015 Author Share Posted September 4, 2015 If the engine has no other symptoms other than higher LTFT the fuel injectors might be a little dirty. I had good results with a Redline fuel injector cleaning product early this year when I had a lean condition that set a code. I first ran some techron cleaner at 1.5x the recommended concentration and it provided a significant difference within a quarter tank. After another tank of regular gas the code returned. I then tried the Redline stuff and the problem hasnt come back since. Try the techron stuff first. If you notice a decrease in trim then you know its just the injectors that need cleaning. This is the first car I've ever had that had a lean code due to dirty injectors. ok thanks. I actually have a bottle of Royal Purple fuel system cleaner waiting to be used - just waiting til the tank is near empty! Link to comment Share on other sites More sharing options...
baconbits Posted September 4, 2015 Share Posted September 4, 2015 Hey all, I'm becoming obsessed with my fuel trims. My LTFT at idle is 10.2, and usually around 11 at cruising speed. This, to me, tells me I don't have a vacuum leak. So far I've: - cleaned the MAF - replaced front 02 sensor - replaced my PCV (what a job that was!) - had my dealer do a smoke test for intake leaks - none, according to them - checked my airbox - it's sealed - replaced my MAF O ring What next? one big question I have - when I removed the intercooler, there were no O rings between the turbo and intercooler, nor between the other thing (blow-off valve?) on the other side of the intercooler. Should there be O rings here? Could that cause my issue? How does a smoke test not find this? Those are definite post-MAF air leaks both in boost and vacuum (to an extent). I'd get those fixed before trying anything else. Link to comment Share on other sites More sharing options...
Bostonian1976 Posted September 4, 2015 Author Share Posted September 4, 2015 How does a smoke test not find this? Those are definite post-MAF air leaks both in boost and vacuum (to an extent). I'd get those fixed before trying anything else. Sorry I updated that I did find an o ring on the turbo side. The BOV Side I haven't taken off yet, but unless it's a small gasket, I didn't see one. I replaced the turbo side one with the reusable gasket that someone posted earlier while I was in there To say that my dealer didn't inspire confidence is the understatement of the year, so I don't have a ton of faith in their 150 dollar smoke test Link to comment Share on other sites More sharing options...
Max Capacity Posted September 4, 2015 Share Posted September 4, 2015 There is a o ring on the BOV side. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Plain om Posted September 4, 2015 Share Posted September 4, 2015 Subscribing to this thread. My 07 is a 2.5 non-turbo, but I've been struggling with trying to explain low IAM and somewhat high fuel correction at anything above idle, manifested in high, but not high enough to trigger a code, A/F Learning values. I have a thread in subaruoutback.org http://www.subaruoutback.org/forums/66-problems-maintenance/254522-logging-ecu-data-2-5-non-turbo-what-about-iam-what-value-do-you-have.html Link to comment Share on other sites More sharing options...
silver05xt Posted September 5, 2015 Share Posted September 5, 2015 ok I'm adding a few data files. Just drove to Rhode Island and LTFT was between 14.1-14.8 most of the time. Help!! do you guys see anything in the files that would cause this? thank you! yes this is the OP under a different username I must have created File 1.csv Link to comment Share on other sites More sharing options...
Bostonian1976 Posted September 6, 2015 Author Share Posted September 6, 2015 I'd greatly appreciate the help here Link to comment Share on other sites More sharing options...
JmP6889928 Posted September 7, 2015 Share Posted September 7, 2015 Mr. Gasket 738G Link to comment Share on other sites More sharing options...
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