I am trying to get my MAF scaled correctly after installing an ETS intake. None of my LTFTs have gone over 4.5 (+ or -) since I put it on. Yet, my STFT will hit 20s in either direction. I had tried to rescale it this past weekend, using my memory of l2r99gst's How to (no internet at home). The big problem I was having is that I would have +20 and -20 STFT at the same Hz values, with LTFTs being the same. What do you guys do with that kind of info?

My WB is fluctuating like crazy now. It will swing from sub 10s to over 17 at cruise, inconsistently. So I know that something needs to be changed. Its just that my LTFTs are within reason, and Im not sure that using solely STFT (o2 feedback) is the way to go.

What conditions do most of you tune your MAF in? All conditions? Solely cruising at a specific TPS, as RPMS rise?

Are most of you tuning your MAF in the open loop areas of the map? I would think that reported load would be more accurate, just wondering if its worth it.

Anyone care to give me a few pointers?

Thanks
-CB

 

I logged a whole bunch yesterday and then filtered out all of the decel/0% tps areas. Then I sorted my log by airflow, and started grouping the data to where I had a group for every entry in the MAF Scaling map. Then I just averaged my LTFT and STFT and added them together, then applied the equation for the map change. I only had a couple of Hz areas that had more 5% either way. I made all of the changes and ended up with a map that was not linear at all. From the drive this morning, it is better. But still having full rich/full lean issues when cruising.

How much of the data that I am looking at is useless and screwing up my averages? What other conditions should I filter out? Am I right in assuming that I should be filtering out all of the fuel cut conditions? It is just that I am getting conflicting data for the same Hz ranges.

 

Ive been reading that +/- 10% is bad. Is that just for LTFTs? How do you tune using STFT that fluctuates from -25 to 25 at the same airflow readings? Am I right in assuming that the +/- 10% rule is for STFT as well? I know that they avg out to 0, but it shouldnt be swinging that much, and most likely causing my full rich/full lean cruising conditions. I can feel the car bog, then look at the WB and it is in the 17s, or 10s. Should I ignore this, and simply rely on my LTFT #s?

WOT is completely fine. I havent touched my fuel or timing maps since I put the intake on. Only difference I have seen is about .2-.3 richer than before.

I really would appreciate some input here.

-CB

 

STFTs are going to vary a lot, depending on conditions. I don't necessarily think there is a 'normal' range. It goes from -25% to +25% for a reason.

If you are getting drastically different readings at the same airflow levels, it may simply be due to the intake setup and may not be completely tunable. I have shown in other threads how some intakes screw up the airflow through the MAF on throttle let-off, for example. The airflow is 'over-counted' for a second or so afterwards and there is a rich spike, and stalling on lift-off. I suggested a patch to fix this specific condition, but I don't think anyone has had anytime to look into it.

For your situation, the best you can do is the following:

Try to either idle or cruise at a bunch of different Hz levels. Don't just go for a drive and use the average. That method may work, but then you are averaging all different conditions, such as acceleration, deceleration, etc. Do a steady cruise or RPM in neutral for a certain airflow Hz. Then look at what the STFT and LTFT are doing. Make your final MAF scaling based off of that data. That should correct for your intake.

However, it's not going to correct for varying conditions of on/off throttle, etc. The STFT is going to vary. If the intake truly messes with the airflow metering enough, there isn't anything that MAF scaling is going to do to fix it.


Eric

 

Thanks for the response.

After thinking about it more over the weekend, I think there isnt a whole lot I am going to be able to do here. If my LTFTs are within +/- 5%, then the MAF is scaled, and its just the intake causing erratic readings. Isnt there a MAF sensor filter map? Does that have anything to do with it?

It doesnt stall on lift off or anything and is driveable. Its just that I get full rich/full lean swings on the WB when Im just cruising along. Im sure my mpg is out the window. I had a cone filter on the stock intake for a while and never experienced any of these issues.