All_talk Posted January 21, 2005 Share Posted January 21, 2005 Nice point Gary! If our fuel system is optimum though, why did my air/fuel ratio change from an optimum 12.0:1 air/fuel ratio to a 13.0:1 between dyno runs? It even went up to 14.0:1 and all I had done was a pulley install. Perhaps playing with the maf sensor screw could've 'Garnered' better results. It might have (though it may only affect idle mix as Russ said), and I am a firm believer in tuning the system to peak performance WITHIN its intended scope. It’s a production automobile and the factory can’t afford to take the time to tweak each car so there is undoubtedly some room for improvement… but I doubt that a fix for running lean at 14 pounds of boost falls into the intended scope. I’m not sure I would describe the stock system as “optimum” but it is well engineered and before we start second guessing the thousands of hours in its design we need to be sure we full understand it. At this point our homework seems incomplete and I doubt we will ever gain access to the information needed. But truthfully what would be the point? If I’m going to spend the time to become a fuel management system programming expert I might as well learn about a modern system with full adjustability. As to your mixture issue on your last dyno run, that’s a puzzler, I suspect a instrumentation problem could be the source, but if not something strange is afoot, because a pulley change shouldn’t have caused a shift in A/F. BTW, great work on the dyno runs, it adds some much needed data to these discussions. Gary Quote Link to comment Share on other sites More sharing options...
4WDFrenzy Posted January 22, 2005 Share Posted January 22, 2005 I have no problems with the running lean with higher boost, but only to a certain extent. After installing my RRFPR, it helped out 10 fold. It runs much richer while in boost than it did with stock fuel pressure regulator. Right now the pressure is adjusted to the same as stock, but I plan on upping the fuel pressure to either 38 or 40psi, but only after I am able to get rid of the stupid fuel cut. And yes I am going to try to do it without the help of MS. I know most of you probably would't advise it, but I am going to try. Besides, I don't plan on running more than 14psi of boost anyway. Quote Link to comment Share on other sites More sharing options...
Mr. Carb Posted January 23, 2005 Share Posted January 23, 2005 Hmmm, I need to lean out my ea81 turbo, I don't know if it's MAF has an adjustment screw on it or not, Will have to look. Everything else has been replaced at this point except the MAF and the throttle position sensor. Passes Idle. But it's a little to rich when it's dynoed at 25mph running around 1800 rpms. I haven't been able to find any service manuals that even talk about the ea81 mpfi turbos..... Quote Link to comment Share on other sites More sharing options...
naru Posted January 24, 2005 Share Posted January 24, 2005 Hmmm, I need to lean out my ea81 turbo, I don't know if it's MAF has an adjustment screw on it or not, Will have to look. Everything else has been replaced at this point except the MAF and the throttle position sensor. Passes Idle. But it's a little to rich when it's dynoed at 25mph running around 1800 rpms. I haven't been able to find any service manuals that even talk about the ea81 mpfi turbos..... Mr.Carb-You`ll be sorry if you mess w/that.Mixture is feedback controlled during cruise anyway.Check the airflow meter potentiometer for smooth resistance change thru the range of movement of the flapper door instead. Are you still trying to pass emissions without a catlyst? That could be problematic. The 84 FSM has ea-81t info.Here is the troubleshooting chart for an ea-81t w/high HC or CO: http://www.ultimatesubaru.org/photos/showphoto.php?photo=3971 Quote Link to comment Share on other sites More sharing options...
Mr. Carb Posted January 24, 2005 Share Posted January 24, 2005 Mr.Carb-You`ll be sorry if you mess w/that.Mixture is feedback controlled during cruise anyway.Check the airflow meter potentiometer for smooth resistance change thru the range of movement of the flapper door instead. Are you still trying to pass emissions without a catlyst? That could be problematic. The 84 FSM has ea-81t info.Here is the troubleshooting chart for an ea-81t w/high HC or CO: http://www.ultimatesubaru.org/photos/showphoto.php?photo=3971 theres no adjustment screw on an ea81t maf anyway. Uhh, it's passing idle, it's failing in the CO(%) at cruise, everything else passes now. the catlyst takes care of HC's from my understanding. And it appears to have one. I posted a seperate thread to talk more about this particular topic with emissions. Thanks for the help. Quote Link to comment Share on other sites More sharing options...
rallyruss Posted January 24, 2005 Share Posted January 24, 2005 mmm nope CO is a product of a rich mixture (or failed cat) HC is unburned fuel (Misfire) cats reduce both HC and CO but ony to a point. Quote Link to comment Share on other sites More sharing options...
4WDFrenzy Posted January 25, 2005 Share Posted January 25, 2005 Now this is purely hypothetical, but I took a look at a turbocharged Saab MAF in this junkyard right outside of the base, and the plugs on the MAFs(both the EA82Ts and the Saabs) and they are identical, with the exception of a wire that comes out of the bundle and goes to the slot that is empty on the Subaru's plug. Now if I'm thinking correctly, that wire has something to do with the fuel enrichment screw sending a signal to the ecu. I'm just wondering if there is a way to activate this function by running a wire from that slot to the empty slot on the plug to the ecu, and if so would it be of any real use? Quote Link to comment Share on other sites More sharing options...
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