Can some bolt-ons offset rich A/F ratio?
04-05-2005, 08:35 PM
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Can some bolt-ons offset rich A/F ratio? From some reading done here on LS1tech.com:
Seems that most of the trouble with some of the major bolt-ons (like headers) is that when just driving around normally the PCM learns to add more fuel to maintain the A/F ratio and thus the LTFT is a positive number. (There is also that problem with the O2 sensors being farther away and colder -- but I am not sure whether this causes a rich bias too.) This causes an overly rich condition when the engine goes WOT because of the cruising rich bias is added to the PE value and often results in too much fuel for the air flow improvement. If this is correct...
1) is there a way to fool the PCM into leaning out the A/F at cruise? Something like the timing tricker but instead of tricking it to think the inlet air temperature is colder, make it think it is hotter?
2) do some bolt-on mods (ported MAF ends?) cause the PCM to go leaner? If so can they be used to offset the rich condition that something like headers can cause?
Thanks!
Seems that most of the trouble with some of the major bolt-ons (like headers) is that when just driving around normally the PCM learns to add more fuel to maintain the A/F ratio and thus the LTFT is a positive number. (There is also that problem with the O2 sensors being farther away and colder -- but I am not sure whether this causes a rich bias too.) This causes an overly rich condition when the engine goes WOT because of the cruising rich bias is added to the PE value and often results in too much fuel for the air flow improvement. If this is correct...
1) is there a way to fool the PCM into leaning out the A/F at cruise? Something like the timing tricker but instead of tricking it to think the inlet air temperature is colder, make it think it is hotter?
2) do some bolt-on mods (ported MAF ends?) cause the PCM to go leaner? If so can they be used to offset the rich condition that something like headers can cause?
Thanks!
04-05-2005, 08:44 PM
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With these motors lean is what you want to avoid. It causes detonation, which will kill your all aluminum motor. Most cars come set a little rich from the factory to avoid this. Headers can make the car a little richer, but most other mods (lid, K&N filter, MAF or MAF ends) lean it out. A good rule of thumb is if you mod the intake, mod the exhasut too.
04-05-2005, 10:58 PM
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My car pops like a bastard. Every time I shift I can hear the gas exploding in the pipes...
All I have is what's in the sig.. + K&N Filter. Do you guys think my cats will last running like this?
All I have is what's in the sig.. + K&N Filter. Do you guys think my cats will last running like this?
04-06-2005, 08:21 AM
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Originally Posted by NateLS1
My car pops like a bastard. Every time I shift I can hear the gas exploding in the pipes...
All I have is what's in the sig.. + K&N Filter. Do you guys think my cats will last running like this?
All I have is what's in the sig.. + K&N Filter. Do you guys think my cats will last running like this?
To the OP, I agree with the first reply.. If all else fails, get a tune... :\
