MAF Tuning in SD- Way Lean when coasting or braking

[BlackGMC]

Well I got my VE table dialed in with in 1% so I decided to reenable my MAF to tune it via BEN correction. Everytime I would take my foot off the gas it would go way lean (18+) in the lower MAF Hz ranges. I would apply the BEN correction and it reflash then it would do the exact same thing. I have done this same process before my headers and new exhaust setup. I also put my WB after the Y pipe so it is farther down stream, previously it was next to the first factory O2 sensor... I don't think I have any exhaust leaks, do you think the placement of the WB is the problem? Attached is my tune and loggs.

AutoVE-002_0003 = MAF Disabled, AutoVE tune
AutoVE-002_0004 = MAF Enabled

Log_0003 = MAF Enabled Log...

Any help would be great!!!!

[BlackGMC]

The wierd thing is it only does it when the MAF is enabled in Open Loop. In Closed loop or Open Loop w/ MAF disabled it does not do it.....

[dc_justin]

Only thing I can attribute it to is very small leak that develops under such extreme vaccum. My truck had the same issue when going through and MAF tuning it long long ago. In the end, I decided not to worry about it. This will typically be in DFCO once all is said and doen.

[BlackGMC]

So should I just filter out anything below say 2000Rpm to eliminate the bad areas? Another thing I read was that I might need to scale up my MAF table to start with since I am running off a stock table. The thread said that headers will tend to lean things out quite a bit. Or maybe my WB is just a piece of shit and I am going to swap in my old one when I get a chance...

I tried logging Dynair vs MAF and got some really wierd readings. So spots on the MAF log would between 0-5 then the adjacent cell would be alot higher. The readings were not consistant at all.

[TAQuickness]

I can't look at your tunes at the moment, but is DFCO disabled while you tune the MAF?

[BlackGMC]

Yep, DFCO is disabled

[mr.prick]

hard deceleration will tend to make you lean,
this is one reason to have PE mode enabled
and set aggressively at high RPM.
the engine seems to pull more air in when you are decelerating,
also manifold vacuum rises and MANVAC has an effect
on the injectors.(my theory anyways)
http://smiliesftw.com/x/augentreher.gif (http://smiliesftw.com)

[BlackGMC]

I did have PE enabled. I am just going to log Dynair vs MAF Freq, it was suggested earlier by Justin, but I have having problems, apparently I had the cell width locked so I was only seeing the ones digit and a bunch of decimals so I thought it was not working... I increased the width and the values from the Dynair log looked pretty close to my stock MAF table. So I am going to hopefully get some loggs this weekend when it is not so cold outside...

Learning to tune is fun, but at times a pain in the ass....

[TAQuickness]

do you still have stock injectors?

I found my SVO42's don't squirt below a commanded 1.7xx ms PW

[BlackGMC]

Yep stock injectors, I have never touched the IFR table either, I have not logged my IDC in forever but I don't think a 4.8 w/ headers only needs it...

[dc_justin]

do you still have stock injectors?

I found my SVO42's don't squirt below a commanded 1.7xx ms PW

That's a legit question, but the thing here is that it is fine in SD, lean in one area in MAF... High vac. With the throttle closed, vaccum is high and its pulling air from wherever it can, and if that means a pinhole leak on one of the intake gaskets, then you better believe it's coming in there.

My truck would spike to 17-18:1 from 2400-2600rpms on decel only with the MAF tune. That one particular spot only. I spent a few weeks trying to figure it out to no avail. Could only attribute it to a minor leak.

In the end, with DFCO enabled, it'll be long-since enabled by the time this lean area would occur.

[mr.prick]

i didn`t see any WBO2 data or PIDs selected in that log.
how do you know you are hitting lean without WBO2, or
am i missing something? http://smiliesftw.com/x/doh.gif (http://smiliesftw.com)

[BlackGMC]

I do have a WB and it was in the log, it is an AEM, you have to make the PID for it.

Here is a pic of what I am talking about

http://i27.photobucket.com/albums/c185/BlackGMC/LogPic.jpg

[mr.prick]

I do have a WB and it was in the log, it is an AEM, you have to make the PID for it.

Here is a pic of what I am talking about

http://i27.photobucket.com/albums/c185/BlackGMC/LogPic.jpg
ahh no wonder.
what is the PID? please post the notepad.

[BlackGMC]

ahh no wonder.
what is the PID? please post the notepad.


Here you go..

[mr.prick]

thanks

[mr.prick]

also when i open your log i noticed you are using imperial settings for PIDS.
imperial setting for MAP is inHg, and in the tune tool imperial is in PSI.
i am not sure if this can cause any problems but i thought i would
bring it to your attention.
this has been a snafu since version 7.4
http://forum.efilive.com/showthread.php?t=4908&highlight=problem+7.4

[BlackGMC]

I use KPA for all my MAP setting... All that just depends how you have settings setup..

[mr.prick]

the first time i enabled MAF after VE tuning
i had to raise the whole table like 20% across the board,
but i had gone from stock to stroker and the VE table
was completely reshaped.

[BlackGMC]

I found out what was causing the problem. My Magnaflow Y-pipe was leaking, crappy factory welds.... My Wideband sensor is right after the Y-Pipe.

http://i27.photobucket.com/albums/c185/BlackGMC/Truck/Exhaust/Leak-04.jpg