When is VE in control vs. MAF?
Mar 5, 2007 | 09:27 AM
#21
Originally Posted by dewmanshu
ARGHGHGHH!!! Then how the hell are some people "supposedly" running these 2bar/maf combo tunes where this is exactly what is happening..."supposedly".
I played with a truck and it "seemed" to work for me, failing and returning. SInce I didn't know of a bit staus to use, I just made the MAF like +35% rich after my fail hrtz. Then I tuned it in SD making everything before 8000hrtz some what lean, around 3 to 5% lean. Then re-enabled the maf and tuned it so the tune was fairly spot on. Then I ran it hard. It would not go super rich (obviously due to fail rate) but it stayed spot on during normal driving. Leaving me to believe it was following the maf which i tuned fairly spot on earlier versus SD which was fairly lean. And also left believing the failing of the MAF was only temperarly. Worked well for a day. Next day it went back to as you are describing(which quiet frankly is what I always expected it to do, but "supposedly" others have it working.
I played with a truck and it "seemed" to work for me, failing and returning. SInce I didn't know of a bit staus to use, I just made the MAF like +35% rich after my fail hrtz. Then I tuned it in SD making everything before 8000hrtz some what lean, around 3 to 5% lean. Then re-enabled the maf and tuned it so the tune was fairly spot on. Then I ran it hard. It would not go super rich (obviously due to fail rate) but it stayed spot on during normal driving. Leaving me to believe it was following the maf which i tuned fairly spot on earlier versus SD which was fairly lean. And also left believing the failing of the MAF was only temperarly. Worked well for a day. Next day it went back to as you are describing(which quiet frankly is what I always expected it to do, but "supposedly" others have it working.
I would say if most are worried, then just stick to one bar and use the maf, simple.
Rick
Mar 5, 2007 | 11:54 AM
#23
Originally Posted by dewmanshu
so, once it fails it will work again once the hertz is below the fail rate? You don't have to wait until off/on cycle of vehicle power?
i don't see where anyone has said this statement is true yet.
i find it very hard to believe that anyone can get a perfect ve table and not have lean tip in and/or rich decel using a 03 pcm strictly in SD mode. the ve table just does not have the fine tuning ability (ie resolution) to do this.
Mar 5, 2007 | 01:56 PM
#24
Originally Posted by Holty
i find it very hard to believe that anyone can get a perfect ve table and not have lean tip in and/or rich decel using a 03 pcm strictly in SD mode. the ve table just does not have the fine tuning ability (ie resolution) to do this.
Although I do agree, no one will ever get a perfect VE and that is just not practical. So long as the VE/MAF fueling is within +/-4% is absolutely normal.
Mar 5, 2007 | 02:21 PM
#25
Originally Posted by 12secSS
Define your statement a little more, could you please? I have my vehicles VEs and MAFs tuned, if I unplug the O2s and MAF I will not get lean tip in, nor rich decel (turning off DFCO). If you meant lean tip in as 15.2 or leaner, and rich decel as 14.0 or richer. Neither is the case with my tunes.
Although I do agree, no one will ever get a perfect VE and that is just not practical. So long as the VE/MAF fueling is within +/-4% is absolutely normal.
Although I do agree, no one will ever get a perfect VE and that is just not practical. So long as the VE/MAF fueling is within +/-4% is absolutely normal.
Mar 5, 2007 | 02:38 PM
#26
Originally Posted by dc_justin
It's an occurence that is common on radix'd trucks. Mash the pedal from a cruise state and it'll spike lean (15-16:1) for a second before coming back in line. The problem does not occur with N/A f-bodies, as my 02 ws6 will actually jump rich in the same condition. I suspect it has something to do with some throttle enrichment or transient fueling tables that are not presently accessible with EFILive or HPT.
Agreed.
Even with my VE table tuned to almost within 1% (commanded vs actual) i still have a lean spike (15.X to 16.X afr) upon positive tps transitions and when decelerating steady rich of about 13.5 afr. any adjustment to fix these issues results in throwing everything else way out of whack.
Mar 12, 2007 | 11:23 AM
#29
Sorry to bring up an "old" thread, but this can be helpful to this topic.
To remedy that instant lean factor when you mash the throttle, you need to adjust the fuel transient tables. Some of these table depic the pool of extra fuel left over, that the ECM uses during harsh throttle transitions. This fuel, under low pressure, tends boil over easily and allows enrichment. But when you add pressure (open the throttle) and vacuum drops (N/A) or boost rises (FI), it causes the vaporized fuel to rain on the intake port. This causes the inital lean condition you exprience. By allow the ECM to add extra enrichment for harsh throttle transitions, you allow more fuel to stay in the mixture or add extra fuel caused by the vaporized fuel that has now been condense and is no longer atomized. This can also be adjusted, depending on the OS, for how long the extra enrichment is applied. I hope this helps.
Originally Posted by dc_justin
It's an occurence that is common on radix'd trucks. Mash the pedal from a cruise state and it'll spike lean (15-16:1) for a second before coming back in line. The problem does not occur with N/A f-bodies, as my 02 ws6 will actually jump rich in the same condition. I suspect it has something to do with some throttle enrichment or transient fueling tables that are not presently accessible with EFILive or HPT.
Last edited by 12secSS; Mar 12, 2007 at 11:33 AM.