Legacy_GT_Pilot Posted February 26, 2008 Share Posted February 26, 2008 I have StreetTuner and am in the process of calibrating by MAF, and keep running into a problem. When I compare my MAF curve to others who have the AEM Intake (specifically LBGT and SeeeeeYa who have graciously shared this info) my settings are very close except for the area where my car is building boost. From ~2.5 volts to ~4.6 volts I need to remove 3-6% from the stock values, where LBGT and SeeeeeYa are 2-4% over stock values. Everywhere else our adjustments are very comparable (+/- 1%). I understand there might be production tolerances, but not this large. My initial thought is my FIBET values are off. I started with scaling the stock values according to the guidance provided based on injector size (used 23,23,46,46,46,46,46,46,46). I then tried the settings provided by Cobb for PE850's (9,9,18,18,18,18,18,18) and have most recently tried changing these further (4,4,8,8,8,8,8,8,8). These changes get me a little closer, but I still need to remove 3-5% from the stock values in the 2.5 - 4.6 volt range. What am I missing? My WBO2 seems to be working fine - it's giving me consistent values from pull to pull, and I'm very close to my stock narrow-band in the 14+ AFR area.I've got my boost settings running at wastegate pressure (0's for boost targets, wastegate high and low values), and I'm hitting 4.9+ volts at 15PSI around 6,500 RPMs which led me to believe my MAF sensor might be off. I've tried a second MAF that I had on hand and both provide very consistent results. These values were logged on cold days (-5C).I thought I might have a boost leak, but if so I would expect the values 4.8 volts upwards to be off as well, but I'm very consistent with LBGT and SeeeeeYa and I'm hitting my AFR targets here bang-on.MY AFRs seem to be OK throughout the MAF curve with the calibrated values I've created, but I would like to fix the issue if I have one. I don't really want to compensate for a mechanical problem via the tune. FWIW I'm running a 20G, Perrim TMIC, Perrin headers, AEM intake, PE850s, AVO fuel pump, UP, DP, CBE, and a Perrin Turbo Inlet Tube. Any help is greatly appreciated. Dave ________ LOVE STORIES ADVICE Link to comment Share on other sites More sharing options...
rao Posted February 26, 2008 Share Posted February 26, 2008 You will never get it that close - trying to will be an exercise in frustration. Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
LittleBlueGT Posted February 26, 2008 Share Posted February 26, 2008 That sounds like some real nice airflow, looks like you may need a different intake anyways to run 17 psi or so at red-line. If your boost targets are 0, then your FIBET will be off, no? (FIBET is based on boost error, and having the targets at 0 drastically changes boost error) Maybe you meant WGDC was at 0? Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
Deer Killer Posted February 26, 2008 Share Posted February 26, 2008 comparing to other's tables tells you nothing IMHO. For whatever reason the part-to-part variation is gigantic. I don't know how any vendors are offering maps for this intake. Link to comment Share on other sites More sharing options...
Legacy_GT_Pilot Posted February 26, 2008 Author Share Posted February 26, 2008 My boost targets are at 0, and that's what I was thinking last night, but then I read and re-read the Cobb documentation on the FIBET table the way they explain it doesn't agree with that rationale. Tonight I will re-align my boost targets to what I'm seeing in reality and just leave my wastegate high and low tables at 0 and see if that makes any difference. Per Cobb's documentation .... FIBET - Used to inject additional fuel according to the rate of positive manifold pressure change. Works similar to the Throttle Pump adjustment, but reacts to changes in manifold pressure instead of Throttle Position change. Not necessary to change unless dramatic changes to the inlet manifold design have been made (ie: racing intake manifold). As for running out of airflow, I've encountered that a few times already and have ordered the AVO intake. Once that arrives I will be going through this process again. That sounds like some real nice airflow, looks like you may need a different intake anyways to run 17 psi or so at red-line. If your boost targets are 0, then your FIBET will be off, no? (FIBET is based on boost error, and having the targets at 0 drastically changes boost error) Maybe you meant WGDC was at 0? ________ Fix Ps3 Link to comment Share on other sites More sharing options...
LittleBlueGT Posted February 26, 2008 Share Posted February 26, 2008 I honestly only half understand FIBET, but I do know that COBB's explanation leaves things to be desired. Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
Infamous1 Posted February 26, 2008 Share Posted February 26, 2008 As for running out of airflow, I've encountered that a few times already and have ordered the AVO intake. Once that arrives I will be going through this process again. Then why stress, I agree with Rao..... Link to comment Share on other sites More sharing options...
Legacy_GT_Pilot Posted February 26, 2008 Author Share Posted February 26, 2008 I don't think it's a AEM related issue - it's either a table issue or a mechanical issue and I'd like to get in addressed now and continue tuning my car, rather than wait until the AVO arrives and see the same thing. We'll see if the boost targets make things look better tonight. Dave Then why stress, I agree with Rao..... ________ Rohypnol rehab forum Link to comment Share on other sites More sharing options...
Boostjunkie Posted February 27, 2008 Share Posted February 27, 2008 +1 on leaving well enough alone. Frankly, you can chase 1-2% trims all day long and never get them perfect. Small trims don't hurt anything and you will drive yourself nuts chasing them. I'm an OCD perfectionist and I've taught myself to draw the line and not waste time and my sanity chasing things that have no effect on anything. Link to comment Share on other sites More sharing options...
Legacy_GT_Pilot Posted February 28, 2008 Author Share Posted February 28, 2008 Now I'm fairly certain that I've got a post tubo leak somewhere, or a bad sensor. I reverted back to the settings I created from a few days ago and re-logged for about 40 minutes expecting the fuel trims to be good and consistent with what I already logged. When I looked at them I was way off. The trims ranged from -5% to -7%. On another note, do the long-term fuel trims impact open loop operation? Is the open loop AFR targeting affected by any compensations noted while in closed loop mode? Dave ________ MEXICAN COOKING Link to comment Share on other sites More sharing options...
sgt Posted February 28, 2008 Share Posted February 28, 2008 closed loop compensation affects open loop trim in most cars that i've seen. I dont know why subaru would be any different. Also, you should make sure you are using the same gas as well. I've seen trim changes as much as 8% due to different quality gasoline. Link to comment Share on other sites More sharing options...
Infamous1 Posted February 28, 2008 Share Posted February 28, 2008 On another note, do the long-term fuel trims impact open loop operation? Is the open loop AFR targeting affected by any compensations noted while in closed loop mode? Dave The fuel trims for the A/F learning D (+40g/s range) area will effect OL fueling. Link to comment Share on other sites More sharing options...
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