# Winter build complete

**URL:** <https://forums.speedlife.net/t/winter-build-complete/204515>\
**Category:** PittSpeed Automotive\
**Created:** [January 20, 2010, 9:53pm UTC](https://forums.speedlife.net/t/winter-build-complete/204515 "2010-01-20T21:53:01Z")\
**Posts on this page:** 1\
**Showing post:** 20

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**Author:** ![Quik](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/quik/32/5979_2.png) [@Quik](https://forums.speedlife.net/u/Quik)\
**Post date:** [January 25, 2010, 9:52pm UTC](https://forums.speedlife.net/t/winter-build-complete/204515/20 "2010-01-25T21:52:36Z")

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> [@need job STILL](https://forums.speedlife.net/t/need-job-still/41939/72):
>
> Hey Quik, I’m not sure if you know the answer to this, but I have a quick tuning question. When the vehicle reads 128 BLM (block learn mod), it is “supposedly” at stoichiometric ratio. If it reads above 128 does that mean the engine is running rich and the PCM is trying to lean it out, or is it running lean and the PCM is trying to richen it up? Either way, to achieve 12.5-13.3 AFR the BLM would need to be either around 116 or 140 depending which richens/leans.
> 
> I know any exhaust leaks can have an effect on this, so right now is probably a dumb time to adjust the BLM since I heard a little bit of a leak at the header gasket. I also dont have the LT4 KM in yet, so I won’t be playing around with the closed loop spark advance for a little while.

BLM is block learn muliplier and yes is 128 at stoich which is 14.7 however with variences in gas mixtures some ppl set stoich to 14.58 at times to help offset the addatives the oil companies run so you dont run to lean and hurt motor. now to answer yoru question if the value is \> then 128 it is then leaner then stoich. the value is raised cause the PCM is trying to correct for fueling. if the value is \< 128 then the vehicle is rich and the pcm is trying to correct it back

matt if youre trying to tackle this yourself and in over your head some. ill be more then willing to help you dial this car in. you know how to contact me

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