spiderpig Posted June 26, 2008 Share Posted June 26, 2008 can anyone tell me what APv2 table would need to be adjusted to reduce off-throttle or zero load fueling. I am experiencing off throttle backfires between shifts due to too much fuel getting through to the exhaust. I have heard from some folks this excess fuel can be adjusted and from others I hear it cannot be. btw - I have a stock bov in place. thanks Link to comment Share on other sites More sharing options...
Infamous1 Posted June 26, 2008 Share Posted June 26, 2008 What are your complete mods? Your getting the tables confused but I know what issues can cause backfires. Link to comment Share on other sites More sharing options...
spiderpig Posted June 26, 2008 Author Share Posted June 26, 2008 thanks for the reply. here's what I have (mechanically) 2008 spec.b avo380 perrin tmic with stock bov avo fuel pump dw 740 injectors cobb catted dp aem cai stock mid/ypipe and mufflers all were in place at time of tune. the backfires do not occur until I am on the road for 5-10 minutes and the exhaust heats up. lastly the engine was smoked and tested for leaks and there weren't any. Link to comment Share on other sites More sharing options...
Infamous1 Posted June 26, 2008 Share Posted June 26, 2008 The problem you have is there is no way for you to alter the tune. The load base fueling is not what is likely off. My best guess would be the MAF scaling on the intake is horribly off. The only other possibility (tune wise) is too much ignition retarding (highly doubt that). Did you ever get a plot of the AFR on the dyno tune? Link to comment Share on other sites More sharing options...
LittleBlueGT Posted June 26, 2008 Share Posted June 26, 2008 Even though it is a RT table, he may be able to read the ROM with ECUflash, and it might be there. ????????????? Worth a try. 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 June 26, 2008 Share Posted June 26, 2008 Even though it is a RT table, he may be able to read the ROM with ECUflash, and it might be there. ????????????? Worth a try. He has an 08.... Link to comment Share on other sites More sharing options...
LittleBlueGT Posted June 26, 2008 Share Posted June 26, 2008 He has an 08.... I thought the CAN/bus cable is out this month? 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 June 26, 2008 Share Posted June 26, 2008 I thought the CAN/bus cable is out this month? Yeah I was hoping as well. It has been push back again to June 30th, I wouldn't be suprised to see it pushed back once more. Link to comment Share on other sites More sharing options...
spiderpig Posted June 27, 2008 Author Share Posted June 27, 2008 "My best guess would be the MAF scaling on the intake is horribly off" if I get the maf scaling parameters from another aem cai user (whose car runs properly) would it be safe to have my tuner duplicate these numbers on my map? Link to comment Share on other sites More sharing options...
Infamous1 Posted June 27, 2008 Share Posted June 27, 2008 "My best guess would be the MAF scaling on the intake is horribly off" if I get the maf scaling parameters from another aem cai user (whose car runs properly) would it be safe to have my tuner duplicate these numbers on my map? It should run better, but it really needs to be dialed in correctly for your individual car. AEM MAF scaling tend to vary from application to application. Link to comment Share on other sites More sharing options...
qikslvr Posted June 27, 2008 Share Posted June 27, 2008 I basically used the formula in the Cobb spreadsheet for intake calibration/scaling on my AEM. Let's kick this pig! Link to comment Share on other sites More sharing options...
spiderpig Posted June 27, 2008 Author Share Posted June 27, 2008 I basically used the formula in the Cobb spreadsheet for intake calibration/scaling on my AEM. is there any way to get that info so I can check it against my tuner/map? thanks Link to comment Share on other sites More sharing options...
Boostjunkie Posted June 27, 2008 Share Posted June 27, 2008 I basically used the formula in the Cobb spreadsheet for intake calibration/scaling on my AEM. That only gets you in the ballpark. There will be areas of the MAF curve that won't even be close if you do not go through them all and rescale appropriately. I have seen some intakes require 10%+/- in areas even after a global scaler was applied. That is a BIG difference in fueling. Link to comment Share on other sites More sharing options...
spiderpig Posted June 27, 2008 Author Share Posted June 27, 2008 thanks. my tuner sent me a new map in which he told me he reduced the "overrun" setting. it is better but still not right. hopefully one more tweak may fix the backfires Link to comment Share on other sites More sharing options...
Infamous1 Posted June 27, 2008 Share Posted June 27, 2008 That only gets you in the ballpark. There will be areas of the MAF curve that won't even be close if you do not go through them all and rescale appropriately. I have seen some intakes require 10%+/- in areas even after a global scaler was applied. That is a BIG difference in fueling. Link to comment Share on other sites More sharing options...
Boostjunkie Posted June 27, 2008 Share Posted June 27, 2008 thanks. my tuner sent me a new map in which he told me he reduced the "overrun" setting. it is better but still not right. hopefully one more tweak may fix the backfires He reduced the overrun ignition timing retard. I know that a table for that exists in Protuner. I have tweaked that table a bit on some cars with big lift throttle decel pops with some success. Link to comment Share on other sites More sharing options...
qikslvr Posted June 28, 2008 Share Posted June 28, 2008 That only gets you in the ballpark. There will be areas of the MAF curve that won't even be close if you do not go through them all and rescale appropriately. I have seen some intakes require 10%+/- in areas even after a global scaler was applied. That is a BIG difference in fueling. I had the whole procedure in my post and removed it. I basically had said that I started with my stock intake, dialed in the A/F trims close to zero, put on the AEM, applied the multiplier(~.951428 for 66.6mm I.D. of MY AEM) across the scale, adjusted cells of MAF scale where it idles until I got A/F trims back close to zero, then logged and adjusted any MAF scale areas that were off from the requested AFR. When I was done, my requested and actual AFR's were identical across the board. FWIW my AEM CAI has required me to reduce g/sec in quite a few voltage areas to get it to stop running rich. IIRC most AEM owners report running lean, but mine has always ran way rich when left unadjusted. I have one of the first ones made(early 05) through so it may be different than more recent units(66.6mm tube and crooked MAF sensor bung). Again, each one is different. Good Luck. Let's kick this pig! Link to comment Share on other sites More sharing options...
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