rob-2 Posted February 26, 2014 Share Posted February 26, 2014 Low compression = leak somewhere = air and fuel mixture escaping during the compression stroke & inconsistent combustion rates between cylinders = Less efficient per cycle http://www.youfixcars.com/engine-compression-test.html I'm telling you this after running 80psi on two cyls. It cruised just fine on the freeway and I got 24-25mpg no problem Link to comment Share on other sites More sharing options...
WaspGT Posted February 26, 2014 Share Posted February 26, 2014 I built my motor, and I have a large 20G turbo. 20-22mpg in the city. Before I built the motor, 11-12mpg. Link to comment Share on other sites More sharing options...
Xplosivo1 Posted February 26, 2014 Share Posted February 26, 2014 I built my motor, and I have a large 20G turbo. 20-22mpg in the city. Before I built the motor, 11-12mpg. What was the cause of the low mpgs? Link to comment Share on other sites More sharing options...
covertrussian Posted February 26, 2014 Share Posted February 26, 2014 I'm telling you this after running 80psi on two cyls. It cruised just fine on the freeway and I got 24-25mpg no problem Fair enough, that is fairly low comp. What was your usual freeway MPG before issues? 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...
rob-2 Posted February 26, 2014 Share Posted February 26, 2014 Fair enough, that is fairly low comp. What was your usual freeway MPG before issues? About that. The best I'd ever seen was 25-26. Keep in mind I'm in the mountains so it's a bit different. It takes all of 40-50hp to cruise at 75mph. Even with a 50% reduction in 2 cyls the motor is plenty strong. My theory is to maintain 14.7:1 A/F for EPA the motor gets more fuel then it actually needs to cruise at those speeds. Link to comment Share on other sites More sharing options...
WaspGT Posted February 26, 2014 Share Posted February 26, 2014 What was the cause of the low mpgs? Honestly, I'm only speculating here, but I'm assuming the previous owners I purchased the vehicle from never took care of any routine maintenance. I take care of my vehicles meticulously. Sometimes poor fuel mileage might be because of plugs, filters, cheap fluids, or far worse. It's tough to tell, but these are my numbers now. Everything is new, better fuel mileage, etc. Maybe sometimes you just have to go big or go home? I dunno. Link to comment Share on other sites More sharing options...
covertrussian Posted February 26, 2014 Share Posted February 26, 2014 About that. The best I'd ever seen was 25-26. Keep in mind I'm in the mountains so it's a bit different. It takes all of 40-50hp to cruise at 75mph. Even with a 50% reduction in 2 cyls the motor is plenty strong. My theory is to maintain 14.7:1 A/F for EPA the motor gets more fuel then it actually needs to cruise at those speeds. I live in the mountains too, 1300 feet, my daily commute is 100% city (30mph avg) thus I get 15-16mpg. Highway I got 24-25mpg @70mph stock. Now I'm tinkering with the tune and my MPG is starting to go up to 26-28. Also I've only owned the car during winter months (winter gas), will see how summer gas does. As for 14.7:1, that all depends on the engine. I've had engines that got much better MPG at 14.7 then 14.9, or 15.5. I've seen some guys mention that running even richer improved their MPG's because of additional torque, thus less throttle is needed. Once I go on another 1k mile trip I'll play around with AFR's more to get the engine into it's happy range. 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...
rob-2 Posted February 26, 2014 Share Posted February 26, 2014 I live in the mountains too, 1300 feet, my daily commute is 100% city (30mph avg) thus I get 15-16mpg. Highway I got 24-25mpg @70mph stock. Now I'm tinkering with the tune and my MPG is starting to go up to 26-28. Also I've only owned the car during winter months (winter gas), will see how summer gas does. As for 14.7:1, that all depends on the engine. I've had engines that got much better MPG at 14.7 then 14.9, or 15.5. I've seen some guys mention that running even richer improved their MPG's because of additional torque, thus less throttle is needed. Once I go on another 1k mile trip I'll play around with AFR's more to get the engine into it's happy range. I'm at 4500 feet and can get to 8K. In a few weeks I'll do about 25K vertical in a weekend. Winter gas has near zero effect on MPG. What does is the heat up cycle on the motor causing it to run rich. Running rich alone will not improve MPG unless, with the additional tq, you also can lower RPMs. Since we're revving around 3K at freeway speed the less fuel you can put in the better. Also it's hotter, burns better and cleaner when it's lean. It's really for NOx reasons we aren't pushing 15-15.5 stateside. That all said if you're going to play with going leaner/richer get an EGT sensor going to avoid melting your motor. Keep in mind the difference in MPG from 14.x to 15.x will be very small. Link to comment Share on other sites More sharing options...
covertrussian Posted February 27, 2014 Share Posted February 27, 2014 Winter gas has near zero effect on MPG. What does is the heat up cycle on the motor causing it to run rich. Might be based on location, different states have different mandates. Read up about winter fuel, it has less energy then summer fuel. Thus like ethanol it is less efficient. I keep a spreadsheet with my gas millage for all of my cars, I saw an instant -2mpg city on my Forester when I fueled up on 11-01-2013. We had a very warm November in VA. If I'm lucky gas stations will be switching to summer blend on March 1st. It really amazed me, I thought something went wrong with the car and started replacing parts like switching to catles up pipe, timing belt etc. Then I looked at my spreadsheet and exactly on November first fillup my MPG was down to 16 from 18, and has been sitting at under 16 all winter, cold or not (we had weeks at 60*F in December). Running rich alone will not improve MPG unless, with the additional tq, you also can lower RPMs. Since we're revving around 3K at freeway speed the less fuel you can put in the better. Also it's hotter, burns better and cleaner when it's lean. It's really for NOx reasons we aren't pushing 15-15.5 stateside. You have to find the sweetspot for every car. Making more torque at lower throttles means less throttle is needed to keep the car going. This is why it's so hard to find any definite answers on what helps improve gas mileage. Every manufacturer, has different technologies that need different ways of tuning it. I did a test on Tuesday, I zeroed out my WG duty table and set target boost to -14.7 for all but last column. The car would be running wastegate pressures and not building any boost at highway speeds. To no surprise, car felt slower, to my surprise my MPG dropped too, cruise control had to press on the throttle longer to keep me up to speed. Btw I used to be pro lean too, until I saw my MPG drop being lean (on my other cars) That all said if you're going to play with going leaner/richer get an EGT sensor going to avoid melting your motor. Keep in mind the difference in MPG from 14.x to 15.x will be very small. Lean is mean, definitely have to be careful, low load though is not a big issue. It's being lean in medium to high load is bad (like Closed Loop Delay does on all USDM turbo Subaru's!!!!) It's good talking to you, I do think we should have this in a separate thread (MPG theory) since it's not related to this guy's 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...
JmP6889928 Posted February 27, 2014 Share Posted February 27, 2014 Lean=HOT. HOT=MELT. MELT=RINGLAND ! ! ! Link to comment Share on other sites More sharing options...
adj789 Posted February 27, 2014 Author Share Posted February 27, 2014 My car feels slower now! Is there some part of replace a coil that would reset my tune settings? Something else I'm starting to notice is the engine feels like it's bogging, I give it throttle and it just doesn't respond but this doesn't happen very often usually the first few minutes of driving, something is definitely wrong though My mechanic tells me to wait for something to fail I know someone that owns a shop, I'm getting a second opinion Link to comment Share on other sites More sharing options...
Max Capacity Posted February 27, 2014 Share Posted February 27, 2014 You need to plug into the OBD2 port and data log. Hopefully the new guy can do that. Its hard to see what's wrong from our PC's. 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...
adj789 Posted March 4, 2014 Author Share Posted March 4, 2014 Took it to my buddies shop and Cyl 2 misfire again! He thinks I should replace the plugs. I'm not throwing a CEL. Something else that's strange my MPG readout is saying 18MPG. I'm taking back to my usual shop tomorrow. Hopefully they can pin down what's going on. Link to comment Share on other sites More sharing options...
USMC6217 Posted March 4, 2014 Share Posted March 4, 2014 [ame=http://www.amazon.com/OBD2-Diagnostic-Cable-KKL409-1-VAG-COM/dp/B002WIN8VQ/ref=pd_sxp_f_pt"]http://www.amazon.com/OBD2-Diagnostic-Cable-KKL409-1-VAG-COM/dp/B002WIN8VQ/ref=pd_sxp_f_pt[/ame] 10 bucks man and the laptop you already have. You can find the v2 AP cheaper now, I picked one up brand new for 350. Countless people have told you that you NEED to put up the logs. I have recieved a lot of knowledge from other members and by reading the countless tech articles on romraider about the values are, how they work together and how to spot a problem if a value is off. If you changed the plugs and did not do a compression test that was diagnostic time not well spent, you were already there. If you are using a tuner have him pull a learning view and I would really only use the guys who come recommended here. Max capacity already suggest Tuning Alliance and there is Cryo Tuning who comes highly recommended also. Something as small as a vaccum leak can cause a misfire and your a/f learning to spike which correlates to your a/f correction, its a closed loop system. This could all be ruled out by a datalog. The purpose of the forum community is to help each other out, when the advice is given and not heeded people tend to be more hesitant to help. I really hope this doesnt come off the wrong way, im just trying to help you. The information is out there, research and research more. The more you know the less money you will have to spend at various auto shops. Link to comment Share on other sites More sharing options...
adj789 Posted March 4, 2014 Author Share Posted March 4, 2014 No I understand and I plan on doing it, I have the software ECU Explorer and Romraider. I was hesitant to get the cable because of this thread regarding the chipset as I didn't want to get the wrong one but it looks like the Amazon one will be ok for logging. I certainly appreciate the helpful advice here. Link to comment Share on other sites More sharing options...
USMC6217 Posted March 4, 2014 Share Posted March 4, 2014 Im new to the Subaru world also my friend but research is going to be your best friend Sent from my SPH-L720 using Tapatalk Link to comment Share on other sites More sharing options...
adj789 Posted March 4, 2014 Author Share Posted March 4, 2014 Indeed I've been reading up on a lot of stuff and bookmarking parts I want later on down the road. I'm new to the Legacy not Subaru, I had a '98 Impreza RS for about 5 years that I fell in love with, once I saw the 05 Legacys I knew I had to get one. Link to comment Share on other sites More sharing options...
Max Capacity Posted March 4, 2014 Share Posted March 4, 2014 One question, how long do you let the car warm up in the morning ? If it's a long time, that could be where the mpg is going. 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...
adj789 Posted March 4, 2014 Author Share Posted March 4, 2014 Not long, I'll start it and slowly pull out of my neighborhood and there's a small hill I go up and that's when I notice the bogging, I'll give it about 40% throttle and it takes about 3 to 4 seconds to respond and start going faster. However if I just smash the pedal in (say 80% throttle) it will rocket up the hill, but I dont like doing that because theres an intersection after the crest of the hill. Usually the shaking will go away after about 10-15 minutes of driving. I dropped it off at the shop to investigate the misfire. I have the cable on the way, should be here Friday. Should I post the info here or make a seperate thread on the tuning subforum? Link to comment Share on other sites More sharing options...
Max Capacity Posted March 4, 2014 Share Posted March 4, 2014 May be start a new thread here and reference this thread. There are few guy's that hang out here that are great reading log's...I'm not one of them. Good to hear you don't let it warm it. I have a long hill about 2/3's of a mile from the house, there is a short flat straight that I can get the speed and rev's up to 2500 in 4th and the cars climbs the hill no problem, today is was -4F, the car runs smooth. My tuner is www.tuningalliance.com you can send him a copy of your log's and see if he can help. When it comes time for a tune, make sure you use him. My wagon gets great mpg and has lots of power. 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...
stealitall Posted March 6, 2014 Share Posted March 6, 2014 I hope you got he FT232BL chip set or it wont work they way you want... The FT232RL are the newer chip set but will not log for what I heard.. Not long, I'll start it and slowly pull out of my neighborhood and there's a small hill I go up and that's when I notice the bogging, I'll give it about 40% throttle and it takes about 3 to 4 seconds to respond and start going faster. However if I just smash the pedal in (say 80% throttle) it will rocket up the hill, but I dont like doing that because theres an intersection after the crest of the hill. Usually the shaking will go away after about 10-15 minutes of driving. I dropped it off at the shop to investigate the misfire. I have the cable on the way, should be here Friday. Should I post the info here or make a seperate thread on the tuning subforum? Link to comment Share on other sites More sharing options...
USMC6217 Posted March 6, 2014 Share Posted March 6, 2014 here is a crazy question, no where in this entire thread did you mention what fuel you are using. What octance is the tune made for and what octane do you fill up with? Link to comment Share on other sites More sharing options...
adj789 Posted March 6, 2014 Author Share Posted March 6, 2014 I only use premium as it says so I assume the tune was for premium Link to comment Share on other sites More sharing options...
USMC6217 Posted March 6, 2014 Share Posted March 6, 2014 By premium you mean 93 right? Sent from my SPH-L720 using Tapatalk Link to comment Share on other sites More sharing options...
USMC6217 Posted March 6, 2014 Share Posted March 6, 2014 Or 91 whichever is available in your area. Did you get the cable? Sent from my SPH-L720 using Tapatalk Link to comment Share on other sites More sharing options...
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