Well in my case I'm using the AccessPort and AccessTuner to have the car tuned... that program is able to set the boost targets and cut limit on the stock ECU within the software itself, so that's not my issue. Not to mention I have my cut problem at 13-14 psi maybe even less, depending on the circumstances.
How is my 14.9 a bad number? I don't see it constantly, the Dashhawk readings just fluctuate because they update constantly, and like I said I see from 14.5-14.9 hovering around 14.7 mostly, which would be the "perfect" mixture, I've even read that it's actually a tad rich at 14.7 so I'm not too worried about my 14.9.
What are your thoughts/what's your reasoning? Remember these are A/F ratio's.
Reading through this thread has been very helpful. Thanks to all for the great discussion and exchange of information. I am trying to help a friend (with a Speed3) with his tune and I think he is running into the same problems you all are discussing. He recently purchased an AP and loaded the Stage 2+FMIC 93 map. His mods are Cobb SRI, PG Turbo Inlet, PG FMIC, CorkSport Test Pipe, HKS SSQ BPV, HKS Hi-Power Catback Exhaust, and he just installed ITV 22's (he checked the gap before install). He has had all these mods and no tune for at least 6 months, so he got use to his car doing strange things under a variety of load conditions. After loading the Cobb and flashing the map he said that the car was running better, but there was still significant KR. I took it for a ride last night and my impressions were;
1. Much smoother than last time I drove it (5-6 months ago)
2. Pulls hard (to the right if you are not paying attention, torque steer almost caught me sleeping the first time I jumped on it) It was a little bit of a wild ride until I got use to being in a FWD monster again
3. Loosing power WOT around 4.5K, should pull MUCH harder to 6K My current thinking is that he is hitting fuel cut when his car builds 19+ lbs of boost. I think he agrees and said as much last night, but we weren't sure if it was boost cut or fuel cut. After reading a bunch I am leaning (pun intended) toward fuel cut. The big question is, what is causing it. I think it may well be a combination of needing new fuel pump internals, and something in the tune needs to be adjusted, but what?
4. Also loosing power/knocking under less than WOT conditions. Less predictable/repeatable. Not really sure of the cause of this, but I suspect this is also a problem with the relationship between his tune and his mods. Since it is happening under less than WOT conditions I am not as concerned with this since the engine should have no problem protecting itself.
Possible solutions:
1. Tuning out the problem I think this is going to be the best way to go. Fix the tune rather than put a Band-Aid on it.
2. Fuel Pump internals Another friend's idea, and I am thinking he is onto at least some of the problem after doing a bunch of reading, some of it right here in this thread.
3. Using a different map (currently on Stage 2+ FMIC IIRC) Stage 1 maps would drop the boost target and that might fix the problem, although I think it would only be masking it.
4. Some sort of electrical/mechanical fix (EBC, MBC, Boost Cut Defender, Fuel Cut Defender, etc....) Band-Aid, not a good final solution, but could be added for another layer of safety
5. May be temp related. I live in Chicago and he has only had the AP for a few days so it has been cold the whole time. However, I am not haveing the same problems with my wifes MS6 running a Cobb Stage 2+TIHSF tune in the same weather.
Here are a few logs. I tried to name them in a way that makes it easy to tell what you are looking at. It was pretty cold (like 12 deg) when we made these logs. Questions, comments????
I think I answered your thread on the COBB Forums. This car has a failing fuel pump. It is 100% the reason why this car is not running properly. Before you can diagnose any other issues, the fuel pump must be replaced. Let us know if you guys have any other questions.
14.9-14.7:1 should only be seen at cruise and very light load. If you are seeing 14:1 AFR on boost, you are running WAY to lean and you might even see a lean misfire at this AFR (maybe). 14.7:1 is an "ideal" AFR, meaning that if you balance the chemical equation for gasoline+O2, this is the ratio of gasoline to oxygen where the equation is balanced (remember Highschool chemistry?). Here is a very basic equation for burning gasoline: 2 c8h18 + 25 o2 ---> 18 h2o + 16 co2 (simplified). However, gasoline has to have a chance to combine with the available oxygen. In a static and room-temperature environment this is rather easy to acheive. In the hot, high-pressure internal environment of a gasoline-burning engine you need to inject more fuel in order to get these molecules to combine completely and evenly. While 14.7:1 may be the ideal mixture for a 100% balanced burn, it is not ideal for getting gasoline to mix with air. An uneven mixture can cause an uneven burn, this is generally what we call "knock". Uneven burning of gasoline that slams into the piston face instead of a nice even burn that gradually builds cylinder pressure.
Also, gasoline can cool the combustion chamber. Employing chemical cooling as we call it, is a good way to do things like run more timing or increase boost pressure without inducing knock. The added fuel, cools down the cylinder. High cylinder temps are another cause of detonation.
While running stoich is technically ideal, it is still very lean. We find that these cars run best around mid-12:1 AFR. A traditional port-injection car may want to run more like 11:1. The direct injection allows a leaner AFR at high-boost since you get better cooling with the direct fuel spray and better atomization for better cooling and better fuel swirl/oxygen mix.
Travis
COBB Tuning
Mine does that from 2800-3700. I've "pooshed the button", and nothing. Using accessport, fuel pressure ranges from 64-1806. I'm pretty sure mine is my hpfp fuel pump is failing. 138k miles though, that's okay.In the most respectful way, I would almost hope you are wrong. Elsewise...think of all those that have bought the upgraded fuel pumps just to find out the TC system was kicking them in the ass.
