BLM's at WOT
Thread Starter
Safety Car
Joined: May 2002
Posts: 4,010
Likes: 26
From: Somewhere nowhere
From the past 24 hours of scanning the car, and reading the internet, BLM's do indeed affect the fuel ratio at WOT, it's only that the car disables learn mode.
I have seen much mass confusion about this.
misconceptions that the car goes to open loop during WOT.
plenty of other misconceptions about no fuel adjustment which just does not make any sense at all.
my car runs at 150 BLM all day, but the O2 sensor shows 860mv at WOT all day. That tells me it is not running lean. The computer has corrected it very well.
I have seen much mass confusion about this.
misconceptions that the car goes to open loop during WOT.
plenty of other misconceptions about no fuel adjustment which just does not make any sense at all.
my car runs at 150 BLM all day, but the O2 sensor shows 860mv at WOT all day. That tells me it is not running lean. The computer has corrected it very well.
Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
How the BLMs are used differs from ECM to ECM. On the LT1 the stock programming uses them at WOT only when they are adding fuel. Many people modify the program so it ignores them completely at WOT.
Certainly haven't seen any mass confusion about it, at least in the LT1 world, as it's clearly documented numerous places.
Thread Starter
Safety Car
Joined: May 2002
Posts: 4,010
Likes: 26
From: Somewhere nowhere
1989 TPI motor, WOT, I see the o2 readings on my autoxray. they are about ~850mv. They move around slightly, so there is o2 readings at WOT.
and the autoxray shows CLOSED loop.
It does NOT jump back to open loop.
and the autoxray shows CLOSED loop.
It does NOT jump back to open loop.
Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
I now begin to understand the statement about "mass confusion" since you seem to be massively confused...
Which is irrelevant to whether the car is operating in closed loop.
Which is relevant to whether the car is operating in closed loop, if you don't understand the difference between "the closed loop flag is set" and "the car is operating in closed loop."
No O2 feedback = open loop. By definition.
Again, this stuff is all FAQ. Don't want to believe me, go search any tuning forum.
WOT, I see the o2 readings on my autoxray. they are about ~850mv. They move around slightly, so there is o2 readings at WOT.
and the autoxray shows CLOSED loop.
It does NOT jump back to open loop.
Again, this stuff is all FAQ. Don't want to believe me, go search any tuning forum.
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
Using a 165, 727/730 ecm, pe is a 'special condition' as some will debate as "open loop". When entering PE (if the tune is close) it will then lock the blm/int. at 128. It does use a table (power enrich vs rpm) and bases the calculation for afr. on the table and the last blm 'seen' before entering PE to try and achieve the desired afr.
Last edited by mseven; Oct 21, 2007 at 11:18 PM.
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Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Actually, BLMs DO affect WOT operation. If BLM is > than 128 at point ECM goes into PE, ECM will enrich further than the WOT calculation should be. However, fueling in WOT, which is Open Loop, is only calc'd. NB O2 does not affect WOT operation. That's why BLM is "locked" and learn is disabled once in PE mode. O2 feedback affects fueling after certain parameters such as temp and tps% are met.
