Josh280z Posted May 7, 2012 Share Posted May 7, 2012 I understand that you cant run high compression with the stock ECU. I was wondering why that is. I cant find the answer that I am looking for specifically, maybe it's someplace I haven't searched. Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted May 7, 2012 Share Posted May 7, 2012 Because it will detonate. With carbs you can adjust the fuel, stock ecu can't. Also if you want to run a more aggressive cam you can't since the stock ecu can't compensate the overlap. So it would be a little pointless to run the higher compression and turn the timing back. However I don't know if any machine work would help, like opening up the valves and stuff, but again it would be pointless. Quote Link to comment Share on other sites More sharing options...
OldAndyAndTheSea Posted May 7, 2012 Share Posted May 7, 2012 Because it will detonate. With carbs you can adjust the fuel, stock ecu can't. Also if you want to run a more aggressive cam you can't since the stock ecu can't compensate the overlap. So it would be a little pointless to run the higher compression and turn the timing back. However I don't know if any machine work would help, like opening up the valves and stuff, but again it would be pointless. ^ That Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 7, 2012 Share Posted May 7, 2012 I think that y'all are describing the effect of high CR, but not the influence of the ECU and AFM. He's just asking for the reasons the stock ECU and AFM won't work with higher compression ratios, which might not be a valid statement anyway. Might be mixing two issues, better flow and higher CR. My reading is that the ECU and AFM are generally thought to not work with improved breathing or flow modifications, not necessarily high CR. And nothing will really support the advantages of higher CR, it's just an inherent limitation of the L engine cylinder head design. But it seems that, in theory, since the AFM and ECU are supposed to maintain a certain air-fuel ratio, that they should work in the low air flow range, at least up to the limits of maximum fuel enrichment. So lower RPM, moderate driving, should work but you run out of fuel at higher RPM (higher air flow). I haven't seen a real detailed explanation myself, of what happens and why, when you try to use the stock ECU and AFM on a modified engine. Quote Link to comment Share on other sites More sharing options...
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