zmonsterjb

iTrader: (16)

Tuned ve table and I want to re in stall the maf. The car now hits 14.3 -14.7 all day long, but as soon as I install the maf it leans the car out so bad that the aem want even read the afr ( greater than 18)?
what is the deal with it (slp 85mm) maf.
Iam thinking about getting rid of it.

thunderdan74

iTrader: (1)

Thats a good Idea. It's best to use a stock MAF when you're doing a custom tune. If you want the 85mm get a corvette MAF.

Is it in open or closed loop when it hits 18:1? If open, I'd say you're running the wrong MAF table.

YellowToy/A

iTrader: (1)

The SLP is a stock MAF. It has a resister that changes the CAL to look like a 75MM MAF. Remove it and you have a stock 85MM maf. Did you tune the MAF table? I hope you have a wide band. What do you mean leans the car out. A/f ratio or fuel tirms? You the histograms and take data.

jimmyblue

iTrader: (11)

One possibility is, "two wrongs make a right" in your speed
density tune. Like you fix a fuel error with your speed density
air tweaking, but then you look at MAF air and that tweak is
out-of-play.

You might look for a tiebreaker, like a virgin stock MAF to see
whether it's a MAF or listening-to-the-MAF kind of problem.
If listening to a good MAF wrecks your tune then you have
to suspect that the speed density air model was tweaked
against some background (fuel side?) error to get a "right
answer" that sits on a crooked foundation.

slow

iTrader: (7)

add fuel to the maf transfer function. In steady state, (idle should be close to steady state) the maf is the main point of airflow calculation. It sounds like it just needs more air added.

Ryan

zmonsterjb

iTrader: (16)

I would have to say it is in closed, because as soon as it reaches temp or gradually it will peg the aem out.
Are the 5.3 liter tahoe/yukons 85mm, if so I will just put the slp on my truck and the truck maf on the car.
By the way what is the difference in the stock and slp maf?

zmonsterjb

iTrader: (16)

You answered the question I had in the last post. I have a few more.

1.) Where can I get the risistor and what size brand ect... do I need to ask for? I assume that I am going to have to soadeir it, no problem! Just let me know what to get.

2.) I have a aem wideband, as mentioned above, and when I say lean the car out , I mean the aem reading goes beyond 18..... I know this because the gauge dosnt give a reading past 18 and the reading shows "-----" in the display.

Remember the problem happen immeaditly after the car is started as it comes to temp. Therfore I have not even got a chance to pull the car out of the drive way with the maf installed.

zmonsterjb

iTrader: (16)

Not really sure what table your mentiong Ryan, are you useing Hptuners







Thanks fellas for the help.

slow

iTrader: (7)

no, i do not use HP tuners, but in thier software it is Engine, Airflow, General Airflow, MAF Calibration (airflow vs frequency)

It is the table that tells the pcm how much air is going into the motor vs the HZ of the sensor.

Ryan

YellowToy/A

iTrader: (1)

What software are u tuning with? Are the trims updating or not when this happens? What is the commaned A/F ratio? Have u looked at the histograms? What cell is the Hz/aitflow in?

Add air to that cell of the MAF table. To make the SLP maf like a stock one you need to take out the resister. SLP put it in there to make the MAF look more like the stock one.

Frost

iTrader: (45)

You can forget a resistor or anything else besides tuning. A stock MAF tble will not work properly because the air intake tract is not stock. Tune a car and get it perfect WITH a lid, and just removing the lid for the stock one causes the car to go from -1, -2 LTFT all over at cruise to +8 to +11.... so it appears that the stock lid needs 10-12% more fuel than a higher flowing aftermarket lid. You don't believe this is the case though, and it isn't. The airflow moving through the MAF has changed.

Just log AFR error against your MAF table and you will have that new MAF dialed in quickly.

zmonsterjb

iTrader: (16)

Really leaning towards of getting rid of it and running sd. Car stay 14.7 or very close to stoich without the maf all throught the driving range, except in the idel areas wich I am correcting.

YellowToy/A

iTrader: (1)

Maf will help on the change from 14.7 to PE. You just need to tune it. What is ur a/r ate wide open. I hope you have it logged.

Frost

iTrader: (45)

The fact that your car is idling at 14.7 has nothing whatsoever to do with the MAF. That is a product of closed loop control. You need to go back to the stickies and read about the basics.

zmonsterjb

iTrader: (16)

Maf is gone, and car is in sd and constantly hits 14.3 to 14.7, except at idel and w.o.t.
Now to work on that.

Goldfinger911

iTrader: (24)

I converted to SD open loop two months ago after similar MAF problems, and I love it. I never could get the MAF calibrated properly with my mods. So it went bye bye. Now, my car's AFR's are perfect at idle, cruise and WOT and drives great.

zmonsterjb

iTrader: (16)

almost makes the maf seem pointless.

One Bad Z

iTrader: (1)

SD tune F T W!!!!

The tuner in our area stands by his SD tunes. However if the customer wants their car tuned with the Maf, he will do it that way.

Rhino79

iTrader: (7)

Just tune the MAF table, you know that the VE is in line, you just need to tune the MAF now. I have to tweak the MAF on every car I do that has an intake track mod of some sort. WOT fueling comes straight from the values in the MAF table, so if its not right, your PE values will not be close. The MAF is good for what it was meant to do, directly measure airflow.