MAF values = 0 at WOT. Any thoughts???
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Joined: Mar 2000
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From: Boston, MA
Re: MAF values = 0 at WOT. Any thoughts??? (NightRyder)
thats cuz at WOT the computer doenst use the MAF values anymore. it uses preset values. (im like 98% sure on this)
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From: Everett WA
Re: MAF values = 0 at WOT. Any thoughts??? (scorp508)
heh, i knew it was one of thoes... . :D welp, i guess it was that 2% ... :p:
damn, and for once i thought i knew what i was talking about. :jester
scorp, you dont have any ideas then? i figured you knew all ... :smash:
damn, and for once i thought i knew what i was talking about. :jester
scorp, you dont have any ideas then? i figured you knew all ... :smash:
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Joined: Mar 2000
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From: Boston, MA
Re: MAF values = 0 at WOT. Any thoughts??? (NightRyder)
If it helps any the LV8 (Filtered Load Value, which is Grams per Cylinder) is calculated using the MAF & RPM readings to determine how much air per cylinder is being moved.
The LV8 is then used in the "Spark Advance vs. RPM vs. Load" to determine what your Spark Advance is. During WOT you'll typically see at LV8 in the 192 block so you'll NEED the MAF readings at WOT to properly calculate this and get you into the proper spark advance tables.
The LV8 is then used in the "Spark Advance vs. RPM vs. Load" to determine what your Spark Advance is. During WOT you'll typically see at LV8 in the 192 block so you'll NEED the MAF readings at WOT to properly calculate this and get you into the proper spark advance tables.
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From: Ft. Lauderdale FL
Re: MAF values = 0 at WOT. Any thoughts??? (Five Window)
Typically at WOT the LV8 should be 208 (the last reading in the code),
anyways, two thoughts: 1) if the engine is modified you may have managed to peg the resolution in the sensor (the most it can read is 256 gm/sec) the code may have some provision to return that kind of value on the aldl, not sure b/c I haven't really looked into that portion of the 32 or 32b code. 2) You are in the power enrichment (PE) mode- when that occurs, the ecm does not use the maf sensor anymore, it assumes your maf tables yield 14.7:1 AFR and then calculates injector pulsewidth using that assumption and the desired AFR on your PE tables.
Clearly if the car is running well for you and there is no "Check engine" light, you do nothave a problem.
[Modified by Br1dgeman, 2:56 PM 1/23/2004]
anyways, two thoughts: 1) if the engine is modified you may have managed to peg the resolution in the sensor (the most it can read is 256 gm/sec) the code may have some provision to return that kind of value on the aldl, not sure b/c I haven't really looked into that portion of the 32 or 32b code. 2) You are in the power enrichment (PE) mode- when that occurs, the ecm does not use the maf sensor anymore, it assumes your maf tables yield 14.7:1 AFR and then calculates injector pulsewidth using that assumption and the desired AFR on your PE tables.
Clearly if the car is running well for you and there is no "Check engine" light, you do nothave a problem.
[Modified by Br1dgeman, 2:56 PM 1/23/2004]
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From: Taxahoma
Re: MAF values = 0 at WOT. Any thoughts??? (Br1dgeman)
The ecm has an interupt that reads o2, maf, etc (can't remember how often, though 8.xx milliseconds, don't quote me on that) If you look at the PE section of the code you will see that it does not skip reading the current sensor readings, in fact it does use them. In a modified motor the maf will probably read 255 and your probably useing the WOT aft vs rpm table for WOT (talking 32b here). It's been quite a few months since i've looked at the source code and not going into it further here but yes it uses it.
[Modified by Black87c4, 11:06 AM 1/26/2004]
[Modified by Black87c4, 11:06 AM 1/26/2004]
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From: Taxahoma
Re: MAF values = 0 at WOT. Any thoughts??? (scorp508)
Boy your gonna make me look at the source code again huh :D I'll try to remember since it takes a little while to sift through that stuff.
Off the top of my head i think the BPW routine gets the AFR, since BPW is called in PE then i'd say yes it is used. If your maxing out the MAF tho your just guessing on fuel once you hit 255, things like temp, baro, etc can affect your fueling and since you can no longer calculate the real air coming in your in guess mode. I mean it works for alot of people but that's not what the PE table is for, it's supposed to add/subract fuel based on what the sensors say, maf can't say much when you go over it's limit.
Off the top of my head i think the BPW routine gets the AFR, since BPW is called in PE then i'd say yes it is used. If your maxing out the MAF tho your just guessing on fuel once you hit 255, things like temp, baro, etc can affect your fueling and since you can no longer calculate the real air coming in your in guess mode. I mean it works for alot of people but that's not what the PE table is for, it's supposed to add/subract fuel based on what the sensors say, maf can't say much when you go over it's limit.
Team Owner
Joined: Mar 2000
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From: Boston, MA
Re: MAF values = 0 at WOT. Any thoughts??? (Black87c4)
Boy your gonna make me look at the source code again huh :D
If your maxing out the MAF tho your just guessing on fuel once you hit 255
