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logging it of course is best. You want the open loop numbers, that is when all the sensors are doing their thing and you are at WOT wide open throttle. The closed loop stuff will fluctuate but always kinda read like what you have gotten already. Closed loop is just cruising or idling. You want your open loop numbers to be around 13:1 for best performance. (disclaimer) I was advised this by somebody but please have your car tuned by a professional for safety of the motor and performance. Pedro can probably help or FVD. Giac if you can get them to get you on their dyno. I use a wideband 02 sensor.
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FWIW, here is a good study of air filters. I like tests with real data and there is a lot there. Bottom line, there is no free lunch. Interesting read if nothing else...
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@KRAM36
You're welcome. :D ;) Don't forget that your AT-tranny will need an defined amount of variable underpressure to work perfect, and that the intake tube is designed to deliver exactly that underpressure. ;) Also consider not also the Helmholtz but also the Venturi effect when you do things in a new sophisticated KRAM36 way. ;) |
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I *think* the tip connection is only for vacuum, so not a lot of, if any, air movement through it.
you will need a wideband o2 sensor to measure afrs at wot. your car only has narrowband (ie, measures afr values in/around 14.7). ecu uses feedback from the narrow band sensors to keep afr at 14.7 at idle and part throttle though the use of fuel trims (ltft). this is closed-loop operation. at wot the ecu wants to add a bit more fuel to keep things cool (ie, an afr of 13 as suggested by jaay). narrowband sensors don't work in this range so the ecu has no feedback on the afr it is providing - it just adds fuel based on the amount of air measured. this is open-loop. open loop is the most critical, as this is when the engine is working hard and the opportunity for damage the greatest. if the maf is mis-reading air (ie, more air getting in than the maf reads) you may get into a lean situation which can kill your engine (gets hot, detonation occurs, pistons get holes in them). how can the maf misread air? a larger diameter maf tube will do it. non-laminar flow in the tube can do it (ie, as jay notes, the ecu is calibrated to read airflow based on a certain type of airflow, and this airflow can be modified by bends - or the lack thereof - upstream of the sensor) vacuum leaks can do it, vibration can do it (ie, I thought it was good to have the maf closer to the tb for better throttle response, but this also resulted in the transmission of more engine vibrations) etc. the thing is, all the factors that affect air metering at open loop operation are present at closed loop operation, so, check your ltfts and see if they are high. If they are then your open loop afrs will be off (my understanding is that the ecu does not use the closed-loop ltfts when running open loop). a little bit of lean operation is ok; Porsche oem afr at wot is 12.5; moving to a 13 should be fine (will result in more power and better fuel consumption) as long as you use a higher octane fuel. blah blah blah ... |
Radium<<<<<<<<<<< Thank you for the better explanation.
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I don't understand. :confused: |
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You could always stick your car on a dyno and get a plot of the afr across the rev range. My afr / fueling seems pretty good as is so it's hard to see aside from a bit more advance where you can make any significant inroads.
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My readings at idle and engine fully warm. Range 2 (FRA) Bank 1 = 1.08 Range 1 (RKAT) Bank 1 = 2.86 Range 2 Lower (FRAU) Bank 1 = 1.08 Range3 Upper (FRAO) Bank 1 = 1.00 Range 2 (FRA) Bank 2 = 1.11 Range 1 (RKAT) Bank 2 = 4.13 Range 2 Lower (FRAU) Bank 2 = 1.11 Range3 Upper (FRAO) Bank 2 = 1.00 Not sure which MAF reading he was referring to as there are 2 to read from. MAF (HFM) danced between 11 to 13 Mass Air Flow danced between 10.9 to 11.7 I'm also getting P0430 on the Quick Test Porsche Fualt Code 45 Cat Conv. Efficiency Bank 2 |
So I gather from those readings at "WOT" open loop (FRA FRAU FRAO) my AFR is pretty much spot on, but at idle closed loop (RKAT) the AFR is running extremely lean?
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these are closed loop values - no trims generated when at open loop (no feedback from the o2 sensors, so no trims). your fra numbers look good - oem Porsche is +/- 0.1. from what I understand, either
(a) your maf is mis-reading the airflow 10% low - vacuum leaks adding air, turbulent airflow into the sensor, vibration, old maf sensor, dirty maf sensor (oiled filter ...) or (b) your fuel system is delivering 10% less fuel than requested - dirty injectors. again, the 10% is within Porsche spec, so looks all good (although you might need a few more miles to get the ltft to settle down). dunno much about idle, other than, if it is idling ok, then I wouldn't worry about it. |
did a bit of searching for you and the rkat is high. did you reset the ecu? otherwise perhaps check for air leak. a small leak has more effect at idle than it does at part or full throttle.
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14.6:1 is normal for cruise and idle. That number bounces around a bit but is fine. I use an aem uego wideband gauge and sensor to tune up my car along with a piggybacked air flow manipulator. I use an old apexi afc select. I believe any newer one would also work. I dont have logging software but just do it the old school way. Either on a dyno or a good old stretch of road and 4th gear.
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