At Wide open Throttle, Do O2 sensors come into play at all ?

 

Nope. The data from them is not used during WOT

 

Thankie, any idea why then I have light trail of black smoke @ WOT, I know they run rich, any cure other than a cpu tune ?

 

YOu prolly have an ignition related problem, but 02 sensors do come into play with WOT, this comes from later experience if your o2's read lean say anothing past 128+ the computer will carry the difference to adding fuel at WOT, say your o2's are real bad & you read say 140 BLMs just before you open her up, well the car will think that the fuel pump/injectors might be bad & at WOT this would be dangerous, so to be on the safe side the computer will carry the difference of 12blm to WOT hope that helps, this 12blm ontop of the already rich PE table of a stock car ussually means black puff of smoke.

 

Pretty cool info, didn't know that

 

Your BLMs affect WOT calculations, but O2s aren't used during WOT although you can look at thier values. So its a yes/no answer, if low end is not tuned right it will affect up top, but by default the WOT enrichment is known to be factory rich. On the later cars this is called CAT overtemp protect.

 

But like both of you said, O2's are not used at WOT, but their last known BLM will be used as the refrence point in how much additional/subtarcted fuBLMsel the engine will recieve.

Is that right ? Btw, what is BLMs. Electrical signal ?

 

it will not subract fuel in any case but only add if it sees a lean condition before entering power enrichment, BLM means Block Learn Mode, means its a block of your mixture condition that the PCM has recongnized to be most useful in the long term to give you a good short term result, so that it does not have to keep trying a different approach to achive the best mixture every time, it gets it & keeps it in mind as a starting point for the next time you are in that RPM/Load. Weird to explain. But when the computer is resent, its BLM is at 128/128 for long term, than it learns that your programming was not so perfect & starts to add/subract fuel as nessesary to get an actual 128/128 for short term.

 

And to think Bunker, a few years ago, you e-mailed me at 5 AM when I was getting ready to go to work ,to check if my top end was getting the same small amount of oil yours was. You've come a long way.