MAFT Gen 2 - Anyone?

[Drweldin]

Originally Posted by TurboBob

it sounds like the ecu is entering lean coast-down mode.

what are your trims (all of them) doing when this happens?

Bob

Ok - here's what happens:
Car warm, I elevate idle by pedal up to 2000 or whatever....AFR goes to 17-19,
short term trim goes to 79.6% and stays...as does AFR.
Let off pedal, let it idle down, trim goes to 100% for about 3 sec....then plumets to 32.8% (AFR 11's)...stays there for 10 sec....then jumps immediately to 120% (AFR still 11's).... basically stays there.....this is all repeatable if I elevate the idle, just starts all over....including the times at each event.....ideas??

[TurboBob]

Originally Posted by Drweldin

Ok - here's what happens:
Car warm, I elevate idle by pedal up to 2000 or whatever....AFR goes to 17-19,
short term trim goes to 79.6% and stays...as does AFR.

because the airflow is really low at that RPM, the ecu thinks you are decellerating. and leans out the fuel. If it is troublesome, you will have to richen up this spot.

Originally Posted by Drweldin

Let off pedal, let it idle down, trim goes to 100% for about 3 sec....then plumets to 32.8% (AFR 11's)...stays there for 10 sec....then jumps immediately to 120% (AFR still 11's).... basically stays there.....this is all repeatable if I elevate the idle, just starts all over....including the times at each event.....ideas??

your idle appears too rich, the O2 trim dives to its minimum to try to correct the problem, and since it is still rich after about 10 seconds, it gives up.
Try leaning the idle out some.

what are your regular trims reading? Remember, trims do not read straight percent, they read 4X of the actual fuel correction. So for a trim of 80 the ecu is pulling about 5%

Bob

[Drweldin]

Originally Posted by TurboBob

because the airflow is really low at that RPM, the ecu thinks you are decellerating. and leans out the fuel. If it is troublesome, you will have to richen up this spot.





your idle appears too rich, the O2 trim dives to its minimum to try to correct the problem, and since it is still rich after about 10 seconds, it gives up.
Try leaning the idle out some.

what are your regular trims reading? Remember, trims do not read straight percent, they read 4X of the actual fuel correction. So for a trim of 80 the ecu is pulling about 5%

Bob

My lo and mid are 81.2%......Hi is 98.4....the mid was in the mid 90's recently, then went down for some reason....how do you suggest I lean the idle? By lo load RPM or MAF g/sec? Currently my idle is just running off the -36 mainscale for 560cc injectors....

[TurboBob]

Originally Posted by Drweldin

My lo and mid are 81.2%......Hi is 98.4....the mid was in the mid 90's recently, then went down for some reason....how do you suggest I lean the idle? By lo load RPM or MAF g/sec? Currently my idle is just running off the -36 mainscale for 560cc injectors....

you can use either one to adjust the tune, generally I suggest the low load page in cases like this.

Bob

[twinturbvr4]

Hey fellas, I think I'm understanding enough to be running fairly well.. just a few questions I was hoping to understand a little better while you guys are actively chattin here (since you 2 have helped so much so far )

First off, whats a good TPS voltage to enable AFR tracking, same goes for RPM.. Gain, is a higher or lower value better..

Second, what exactly is MAG g/sec and what kind of adjustments can I make with this..

Think I might be bumpin up to 550 injectors soon.. have been able to boost to about 18psi (around 20psi spike) and everything holds pretty well with all of the adjustments you guys suggested earlier, but seems to go kind of flat as far as accelerating in the higher rpm ranges, I richened my HI-load high rpm range, and that has helped a bit, but would like to go beyond 18psi without sputtering or loss of acceleration up there.


Thanks for all the help!.. Good luck to all (including me) with the tuning!

[Drweldin]

Originally Posted by twinturbvr4

Hey fellas, I think I'm understanding enough to be running fairly well.. just a few questions I was hoping to understand a little better while you guys are actively chattin here (since you 2 have helped so much so far )

First off, whats a good TPS voltage to enable AFR tracking, same goes for RPM.. Gain, is a higher or lower value better..

Second, what exactly is MAG g/sec and what kind of adjustments can I make with this..

Think I might be bumpin up to 550 injectors soon.. have been able to boost to about 18psi (around 20psi spike) and everything holds pretty well with all of the adjustments you guys suggested earlier, but seems to go kind of flat as far as accelerating in the higher rpm ranges, I richened my HI-load high rpm range, and that has helped a bit, but would like to go beyond 18psi without sputtering or loss of acceleration up there.


Thanks for all the help!.. Good luck to all (including me) with the tuning!

Ive got my AF tracking throttle voltage at 1.9x....gain I think you want the lowest value to accomplish good response. Mine is at 12%. MAS grams/sec is just a airflow measurement....you can watch this value on the sensor mode I believe...just another way to adjust on volume vs. (instead of just) rpm....I don't currently do any adjustment with g/sec....but Im sure it would make more sense than rpm for some situations....one thing ive noticed with AF tracking: it seems like I need to bring the "lean max %" up to 12% or more to accomplish 11.5 afr....but I think it's because of these piggish 560 EVO injectors....so far I average 11.2 AFR or so, so I think I need to raise it even more....but my point is, I do notice it working as I raise it...just have to raise it more than I anticipated I would.....what turbos you using? If 9b's, that would explain the "flatness" on top, Im sure....generally I need to lean out in the upper end, rather than richen....I also have timing control though....

[twinturbvr4]

I've got 16t turbos.. which are basically just a hair above the 15gs.. The lean limit I raised to 14%. I tried the TPS at around 1.75 and it was running ok, was actually accelerating very smoothly yesterday.. today, the car was sputtering alot, even just at Mid acceleration.. so I jumped it up to about 4.0 quickly while I was driving. Now Im hitting full boost kind of slowly actually.. the boost builds, just doesnt have as much acceleration punch as before.. gets to 18psi and holds ok.. just still seems laggy.. seems like anytime I run my mainscale at -20 or lower its real laggy, so I usually run between -18 and -19 and get pretty good results.. I have a pretty much brand new lower intake that Im hoping to assemble rails, fuel gauge and 550s on.. not sure if I want to go AFPR yet.. and I hope to do the hotwire kit for my walbro too.. but then I can watch my fuel pressure, and I think 550s are better suited for my turbos..

AFR is set to 11.5 across the board, hit around 12 AFR at WOT and full boost, sometimes goes a lil richer, but not too much usually.

[Drweldin]

Originally Posted by TurboBob

because the airflow is really low at that RPM, the ecu thinks you are decellerating. and leans out the fuel. If it is troublesome, you will have to richen up this spot.





your idle appears too rich, the O2 trim dives to its minimum to try to correct the problem, and since it is still rich after about 10 seconds, it gives up.
Try leaning the idle out some.

what are your regular trims reading? Remember, trims do not read straight percent, they read 4X of the actual fuel correction. So for a trim of 80 the ecu is pulling about 5%

Bob

Couple of observations / questions:
1) I cannot seem to effectively lean the idle. I am going to reset base idle and look at IAC values later....
2) When leaning idle, how long can it take to change AFR? Is it usually instanteous? or should I be waiting a couple of minutes?
3) I can get lo-load page to give me stoich readings at each rpm level with the car warm, and stationary,me just applying and holding trhottle and adjusting....going up thru the rpm range....but, I have to add + 20% or so at 1200 and above-- is this "normal"? second,is this a proper way to tune lo-load?? So I effectively net -17% or so user tune (560 injectors)....but keep in mind, ported heads, free flowing exhaust bigger turbos, etc....so maybe its ok (?) It does sound and feel better with the extra fuel....I have not driven it yet. Im a little worried about the transition from -37 at 800 rpm to -17 at 1200 ....not sure if that will present any issues....
Any good links to tuning?

EDIT: #1 IAC Seems good, and seems to act normal. NEvermind on #3, experimanted and found this is not a good way to tune. While it works with no load, I was indeed rich at cruise afterwards, although a little more fuel in the lower range of the lo load page (rpms) does seem to smooth the car out a tad...

[twinturbvr4]

I usually literally FELT the change within about 5 seconds (FELT the change when making drastic changes.. ie, mainscale) What kind of rpm ranges and fuel adjustments did you make to smooth your idle? When I start my car I have to give it some gas until it gets going (about 10 seconds or so around 2krpm.. otherwise it either dies or idles up and down real low) I tend to sit slightly lean once its warm and idling (around 15.xx)

I think the giving it gas is a vacuum condition I have yet to figure out (since I changed over to an aftermarket BOV I believe..)

I'm at about 18.5 on the mainscale for my 450s.. none of the rpm ranges have negative values, so I know I havent leaned it anywhere..

[twinturbvr4]

Originally Posted by Drweldin

thats what I thought too....it's not too bad or anything...actually the car
is running awesome....best it's ever ran I think....
any suggestions on where to richen it to smooth it out?
That is, lo load scale probably, 1200-2000...? Mid load ? Or would it be better
to adjust it in the MAF scale portion....?

Did you ever get this figured out? I'm having I think the same exact thing goin on.. When I just barely press the gas just to maintain speed it sounds like its drawing alot of air through the intakes and im getting some slight stuttering and its floating around 16 afr.. I've been trying to figure out in my head exactly HOW to adjust this since it can happen at any rpm, but obviously on the LOW load...

Also, whats a good way to richen slightly between shifts, seems that I get around 15+ AFR after I get back on the gas after I go into the next gear.... (feel free to slap me around if thats WAY too vague! )


EDIT: by the way.. thats from page 6