BLMs drop when throttle is closed
#1
Senior Member
Thread Starter
BLMs drop when throttle is closed
I been tuning my part throttle operation via the MAF tables, to get BLMs right around 128. I have made some good progress, but have noticed something in my datalogs. Whenever i back off on the pedal, eg like to slow down for something on the road, the BLMs always drop to around 122. It doesnt really matter what speed/rpm I am going, the BLMs always drop. Now when that happens, my actual MAF readings go down as well, with the throttle closed. But it really isnt an idle condition, so I am not sure I want to touch the MAF tables.
I know there is this DECEL ENLEAN business in the bin, but I have not touched it all. 165 ECM, $6E-ARAP based bin.
Thanks.
I know there is this DECEL ENLEAN business in the bin, but I have not touched it all. 165 ECM, $6E-ARAP based bin.
Thanks.
#2
Supreme Member
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Re: BLMs drop when throttle is closed
Oddly enough after tuning for 5 hours yesterday and doing 7 datalog sessions, i noticed the same thing EXCEPT that in my case it went from around 120BLM at part throttle to 126BLM upon decelerating. I'm obviously running too rich but could the deceleration cause me to go leaner and you to go richer?
im also concerned that when i correct part throttle MAF tables to 128blm will this bring my BLMs too lean to say 134? id like to know if anyone has tried messing with deceleration stuff.
im also concerned that when i correct part throttle MAF tables to 128blm will this bring my BLMs too lean to say 134? id like to know if anyone has tried messing with deceleration stuff.
Last edited by hellz_wings; 07-03-2011 at 10:50 PM.
#3
Senior Member
Thread Starter
Re: BLMs drop when throttle is closed
I am surprised not many comments. Seems like somebody would know something about this. I know in DFCO mode, after backing off the pedal, the injectors get turned off...so should go lean, yes? I know my WB goes way lean and usually pegs it lean, if I back off for long enough. So what is up with my BLMs going down? Maybe I am worried about nothing. The only other thing I saw maybe could affect it, was the Decel Enlean BPW factor, which was set to 1.00 of course. Maybe that could be adjusted.
#5
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Re: BLMs drop when throttle is closed
So what is up with my BLMs going down?
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#8
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Re: BLMs drop when throttle is closed
I didnt see any flags to turn it off. But several constants to enable/disable. Why would you want to turn it off? I can accept what Ronny said above. I dont usually stay in this 0% tps mode very long, so maybe need more time for BLMs to recover. Also curious about going open loop at 0% tps. Did not see that parameter.
#9
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Re: BLMs drop when throttle is closed
I run a different file definition(mask). Yours may not support OL at 0% tps. Yours may however support OL on < certain MPH? Or maybe some other table to flip OL? Dont know.
You may have than option in constantts. I think mine was flags. I may have been wrong. Again I cant remember where mine was. One more thought /comment. There must be a table to turn injector back on to m prevent stall with DE active when car comes to near stiop? I dont have laptop at office or I would take a look.
You may have than option in constantts. I think mine was flags. I may have been wrong. Again I cant remember where mine was. One more thought /comment. There must be a table to turn injector back on to m prevent stall with DE active when car comes to near stiop? I dont have laptop at office or I would take a look.
#10
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Car: 1989 Pontiac Firebird
Engine: 305 Tbi w/lt4 hot cam
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Re: BLMs drop when throttle is closed
Dfco is another animal the injectors turn off so its not just lean but dead lean the engine keeps spinning because the driveline is still turning it also helps cool the motor down because theres no combustion.
#11
Senior Member
Thread Starter
Re: BLMs drop when throttle is closed
Yea I run a 350 TPI setup. After I thought about it, it is a dry intake system, the fuel gets injected right down at the valves for each cylinder. I am running $6E tdf, with ARAP based bin. I dont see much of the OL settings that are mentioned above. But what I do have is several constants for DFCO(11) and Decel Enlean(6). It looks like DFCO is enabled, but I am not so sure about the DECEL ENLEAN. There are 2 constants that look high to me.
Decel Enlean Enable Delta TPS threshold, which is set to 94%.
and Decel Enlean Enable delta LV8 threshold, which is set to 245 LV8.
Those numbers seem high enough that NOT let DE mode to kick in. I need to look at some other bins and see what they are set to.
Keep the posts coming.
Mike
Decel Enlean Enable Delta TPS threshold, which is set to 94%.
and Decel Enlean Enable delta LV8 threshold, which is set to 245 LV8.
Those numbers seem high enough that NOT let DE mode to kick in. I need to look at some other bins and see what they are set to.
Keep the posts coming.
Mike
#12
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Re: BLMs drop when throttle is closed
Right. My error.
If in fact in DE I would think BLM would lock and log would show 128.
Why would General allow DE to affect BLM? Maybe a rising BLM(adding fuel) will help the engine recover after DE event. That would be contrary to OP statement of falling BLM(pulling fuel).
Where is additional fuel coming from? VAFPR drops FP. No added fuel there.
If in fact in DE I would think BLM would lock and log would show 128.
Why would General allow DE to affect BLM? Maybe a rising BLM(adding fuel) will help the engine recover after DE event. That would be contrary to OP statement of falling BLM(pulling fuel).
Where is additional fuel coming from? VAFPR drops FP. No added fuel there.
#13
Senior Member
Thread Starter
Re: BLMs drop when throttle is closed
Right. My error.
If in fact in DE I would think BLM would lock and log would show 128.
Why would General allow DE to affect BLM? Maybe a rising BLM(adding fuel) will help the engine recover after DE event. That would be contrary to OP statement of falling BLM(pulling fuel).
If in fact in DE I would think BLM would lock and log would show 128.
Why would General allow DE to affect BLM? Maybe a rising BLM(adding fuel) will help the engine recover after DE event. That would be contrary to OP statement of falling BLM(pulling fuel).
and yes, i have searched on DFCO, but not sure what the difference is with Decel Enlean. Please keep discussion going.
Mike
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