Setting up MAF..

[taf0422]

Well I did what cobb wanted me to do with the trying to calibrate the MAF but I still can't seem to figure out why/wrap my head around the concept. I was wondering if you guys could set my in the right direction (still a complete noob by any standards). Attached is a log with the 20secs as close as I could get the 100 g/sec..idle.. then the up to 30 g/sec..

The only reason I was looking into calibrating the MAF was because sitting at idle my car will gradually move up to 7-9 + on the LTFT.

If someone a little more knowledgeable could chime in, I'd really appreciate it

[Blackspeed]

in the maf tables (a&b) you need to multiply the g/s in each range by the LTFT %.

0-5g/s x 1.0764
5-16g/s x 1.0218
16-28g/s x 1.0062
28-77g/s x .9828
77 and up x .9984

[taf0422]

by the way..if it makes a difference I'm running stage 2+ 91 v105 fmic

[Blackspeed]

it doesnt make a diff. Do you understand how i came up with those?

[Campo]

I am also a tad confused on the concept of the MAF tuning.

I understand if you are in the negatives you are running rich and need to pull that percentage from the maf tables.

Is the concept of doing this so you can just flash and rip without waiting for the ecu to relearn the trims?

[taf0422]

I sort of understand with the MAF. I know if I'm off on LTFT pretty much the whole way across the board I know how to fix that but what happens If I'm just up in the +7 during idle?? How do I change that?



When I even barely touch the gas it shoots down to 2.3 a little hard and it goes down to 0.8...Any other input? I also feel like its not boosting the way it should. I may see 20psi spike but it will taper quickly to 17 to redline

EDIT: Nevermind..slight over look by me on the MAF part..I think I figured that out. lol but still wondering about the boost. Don't wait it to be a horrible day/money spent at CP-E dyno day. lol

Or do anyone have a map they would feel like sharing? Current mods that I can think of..lol.., test pipe, hks bpv, ptp fuel, cpe cai, cpe inlet, fmic, denso 22's..other mods are in profile

[Blackspeed]

post some logs.
You really dont want to use someone elses map. Just do some more reading and post some logs and people will help you out.

[taf0422]

I will definitely post up some logs as soon as I can get it to stop raining outside.lol

[taf0422]

Here are the logs I just took, it still is wet outside so I'm not entirely sure whats up with these..The boost looks really low...

First log if I remember is 4th gear..

Second log go down to Cell A48 to see 3rd gear

Third log is 1-3rd. on slick roads so wheel spin and letting off was a factor

I'd really appreciate some help! Thanks

[fjames]

I looked at your 4th gear log and to my way of thinking it's pretty impressive. You're right on target for fuel and load with that map (close enough as these things go.) Your boost is low because of the cold weather, but your load is fine so it's doing what it should.

One funny and bothersome thing - your g/s is a little low in general and stops increasing with rpm like it should. could be the log sample rate lagging - you were lifting before it actually showed you were in other words. I dunno ... the low in general could be the CAI - your mods are similar to mine is why I'm comparing my logs to yours and seeing the slightly low g/s, but I've got a SRI and TMIC vs. your CAI and FMIC.

Whatever, it looks good to me except for that weird little thing of g/s falling above 5.5K or so.

How does it drive in general, feel pretty good? Any bothersome cuts?

[taf0422]

Originally Posted by fjames I looked at your 4th gear log and to my way of thinking it's pretty impressive. You're right on target for fuel and load with that map (close enough as these things go.) Your boost is low because of the cold weather, but your load is fine so it's doing what it should. One funny and bothersome thing - your g/s is a little low in general and stops increasing with rpm like it should. could be the log sample rate lagging - you were lifting before it actually showed you were in other words. I dunno ... the low in general could be the CAI - your mods are similar to mine is why I'm comparing my logs to yours and seeing the slightly low g/s, but I've got a SRI and TMIC vs. your CAI and FMIC. Whatever, it looks good to me except for that weird little thing of g/s falling above 5.5K or so. How does it drive in general, feel pretty good? Any bothersome cuts?

Well that makes me feel a little better, especially coming from you. I've seen a lot of your post on tuning...

The car drives great, drives smooth..I do every now and then have the jerky throttle but I've been looking into that on the numerous threads that we have going around. I've actually never had a cut with this map at all. My car generally seems to like this map. Except for at idle, I see +7 on the LTFT. That kinda of drives me insane.

I will have to look into the g/s...I didn't really notice that. lol.

Thanks again for your input!

[taf0422]

anybody else??

[Campo]

I could use a little direction as well.

Here are my logs.
this is following the cobb AP instructions

[Blackspeed]

i highlighted the ranges you need to change in the MAF tables (do maf A and then copy over to MAF b)

you multiply the ranges (g/s) by the LTFT percentage. for example: your 0-4 range needs to be multiplied by 92.19% (0.9219)
let me know if you need more explanation

[08Anamoly]

Per the Cobb tuning documentation, aren't you supposed to account for the sum of the LTFT and STFT when adding percentages to the Mass Airflow (g/s) values?

Example: If STFT is +5% and LTFT is -8%, you would subtract a total -3% to the g/s value. You would multiple the g/s value therefore by 0.97?

From Cobb instructions:

"You want the combination of your A/F trims to be as close to zero as possible." This seems to reference not just the LTFT but the STFT too.

[Campo]

Originally Posted by 08Anamoly Per the Cobb tuning documentation, aren't you supposed to account for the sum of the LTFT and STFT when adding percentages to the Mass Airflow (g/s) values? Example: If STFT is +5% and LTFT is -8%, you would subtract a total -3% to the g/s value. You would multiple the g/s value therefore by 0.97? From Cobb instructions: "You want the combination of your A/F trims to be as close to zero as possible." This seems to reference not just the LTFT but the STFT too.

Ineresting!
Thoughts on this?

PS my STFT are all over the place. been driving for 100 miles or more. jumping to 25 sometimes. But always 0.0 to -1.0 at wot.

Any ideas?

[Blackspeed]

Originally Posted by 08Anamoly Per the Cobb tuning documentation, aren't you supposed to account for the sum of the LTFT and STFT when adding percentages to the Mass Airflow (g/s) values? Example: If STFT is +5% and LTFT is -8%, you would subtract a total -3% to the g/s value. You would multiple the g/s value therefore by 0.97? From Cobb instructions: "You want the combination of your A/F trims to be as close to zero as possible." This seems to reference not just the LTFT but the STFT too.

you might want to quote this sentence as well.

" If you follow the above steps
and capture a datalog, you will not need to follow the steps in this paragraph."

[08Anamoly]

Think that is referring to whether or not you are using historical LTFT data. I am going to call Cobb today to double check on this for clarity for my tune.

[homer]

I,

I am newbie on this forum

Sorry for this stupid question but why we have to do the maf calibration?
My problem is I have part throttle KR, do you think if I do the maf calibration it can eliminat my KR.
I trie to do the maf calibration and I am no sure if is correct?
This is my log

0-5 0.9594
5-16 0.9906
16-28 0.9750
28-38 0.9906
38-77 0.9984
77 and up 0.9984

Do you this it's ok?

[taf0422]

I messed with my map a small bit!! but I found out that the rising ltft at idle are caused by a very small vacuum leak..so when I tear my bumper off next week and get my front bumper painted I will be checking all my connections.

[Campo]

At idle and when I am decelerating my LTFT are - 10.1 what do I change on the maf maps to correct that?

[ToledoSpeed3]

Originally Posted by Campo At idle and when I am decelerating my LTFT are - 10.1 what do I change on the maf maps to correct that?

Blackspeed helped you above where your log showed -7.81% in the 0-5 g/s breakpoint range. There seems to be a lot of people struggling with this concept, so I wil break it down further. Make sure you break in your map for 40-50 miles or so with varied driving and idling before you take the logs for the calibration.

In his example you would reduce your g/s in the MAF table by by muliplying all cell values that are between 0 and 5 g/s by 0.9219 (100% - 7.81% = 92.19% or .9219). In other words, in ATR in your MAF table, start on the left and highlight all values until they get up to 5) . Once highlighted, click "M" on the keyboard to Multiply the selected values. Enter .9219 and click "OK". You have just reduced the values (g/s) for this breakpoint range of 0-5 g/s. You have now told your ECU that your are receving less air at these registered MAF voltages and this should raise your negative LTFT % to be closer to zero. If you are now seeing -10% LTFT in your logs. You would then multiply by .90 instead of .92.

For those seeing positve LTFT values in your logs (ECU is adding fuel to compensate), find the g/s breakpoint range (see the Cobb ATR manual) and multiply the values in the range by a value greater than 1. For example, if your LTFT is +10, then multply the range values by 1.10 (100% + 10% = 110% or 1.1). Highlight values, press "M" and enter 1.1, hit OK. You have now told your ECU that your are receving more air at these registered MAF voltages and this should lower your positive LTFT % to be closer to zero.

Hope this makes sense and helps others out. Achieving perfection is not possible, so don't sweat it to much.

[Campo]

Cool thanks. Crystal clear

When I drive around I see -3 to -5 on LTFT and STFT so I will deal with that soon. I wanna work my way up.

But consider this. The engine knows it is running rich so it is removing fuel to compensate (for me) so how bad is it really to drive around like that? As long as the car has accurate readings it should not matter right?
The only reason I can see for tuning your maf is so that you no longer need to 'break in' the ecu after disconnecting the battery or changing a flash.

[ToledoSpeed3]

Originally Posted by Campo Cool thanks. Crystal clear When I drive around I see -3 to -5 on LTFT and STFT so I will deal with that soon. I wanna work my way up. But consider this. The engine knows it is running rich so it is removing fuel to compensate (for me) so how bad is it really to drive around like that? As long as the car has accurate readings it should not matter right? The only reason I can see for tuning your maf is so that you no longer need to 'break in' the ecu after disconnecting the battery or changing a flash.

What you are saying is true, but only for normal driving conditions and not for WOT. After a decent map breakin period of 40-50 miles, the LTFT is all you should worry about. If that is within +/- 8%, you shouldn't worry too much, but now we also need to consider your AFRs at WOT. The ECU is compensating just like you say during "closed loop" operation to hit the AFR targets using O2 sensor feedback. However, the MAF table also needs to be calibrated for WOT AFRs during "open Loop" when it no longer uses O2 feedback. For WOT the AFR should be logged to determine MAF calibration. If you are too lean, you need to increase the top end of your MAF curve to richen up. If you are too rich, you need to carefully lower the top end of your MAF curve until you hit your desired AFR. I like a WOT AFR in the mid 11's. The MAF table values (g/s) are used for load calculations. Since the ECU targets load, it is essential that the MAF table be as accurate as possible. If you can't raise your MAF table values to hit your desired AFR (still is too lean), then you are likely hitting the "load cap" that has been discovered. See the posts in the ATR section that deal with this subject.

Good luck!