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Old 05-05-2012, 03:06 PM   #1
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Default WOT issue

Just to clarify, once you go WOT, the computer will only look at your PE (command) settings, and then add any possible +LTFTs to the formula, correct?
I was doing some intial WOT tuning, and I THOUGHT I heard somthing like a miss/skip, etc., but the car HAULS BUTT!!!!
When looking at the scan of WOT, the MAF (not used I know but it is recording airflow) and MAP did not have smooth lines, but were slightly jagged. If scrolling over them frame by frame, it was clear the values would flucuate just slightly while accelerating.
Any ideas (Timing is steady with no KR)
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Old 05-05-2012, 06:28 PM   #2
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Yes, at WOT PE is commanding fueling (as long as you haven't altered that) and it will add +LTFTs if you were lean when it went into open loop. What was your wideband showing? When you say the MAF was not used, did you have it in speed density? post up the log...
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Old 05-05-2012, 07:22 PM   #3
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Is this something new or just your first time scanning. MAF will be pretty rough, but MAP should be somewhat stable, though it could jump around a little. Is the RPM graph smooth?

Posting the log would be the easiest way to see.
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Old 05-06-2012, 07:48 AM   #4
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I am using the MAF, Just meant that in WOT I know its not reading it.
MAP, RPM (slightly) and MAF are all jagged. The rpm, screen by screen, had slight dips in it as well (although it is not very noticable now) And although it is EXTREMLY strong, It still sounds like it breaking up.
I didn't save the logs; I am trying to get the AFR to log, so I am constantly logging. As a note, I am getting the AFR information by reading it directly from the AFR gauge while my wife drives. I am betwen 12.8 and 13.1 through the run.
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Old 05-06-2012, 12:48 PM   #5
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Umm, yes the MAF does effect fueling at WOT if you are not in speed density... You are between 12.8 and 13.1 on a blower car? That is very lean - that is naturally aspirated AFR territory... You sure you know what you are doing here? Sounds like you may be about to learn some very expensive lessons in tuning...
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Old 05-06-2012, 02:34 PM   #6
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[QUOTE=BLK02WS6;16279919]Umm, yes the MAF does effect fueling at WOT if you are not in speed density... You are between 12.8 and 13.1 on a blower car? That is very lean - that is naturally aspirated AFR territory... You sure you know what you are doing here? Sounds like you may be about to learn some very expensive lessons in tuning...[/QUOTE]

Yea; Not tuning a blower car
This is my wife's H/C car that I just intalled a FAST 92/LS2 TB on.
My undertanding is that MAF is for steady airflow (crusing)and the VE table is for transition AND for a check for MAF. When the car meets the perimeters for WOT (TP and MAP) it fuels strictly by your command PE, ADDING any positive fuel trims, but ignoring (adding zero fuel) for any negative.I have read that the MAF helps fuel after WOT has been reached, but must confess that I'm not sure how since I have never tuned MAF (per the tuning guide) past 4000 rpm.
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Old 05-06-2012, 06:27 PM   #7
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Okay, I was just going by what your sig says...

The commanded fueling at WOT is determined by the PE table (and adding +LTFTs) - but, just like that says - commanded... that is the target... But, the way you get to the target is based on the values in the VE and MAF tables. The MAF absolutely does effect the fueling at WOT - at around 4000 rpm, the MAF actually starts effecting fueling more than VE (based on the way the tables are constructed).

The correct way to tune fueling is to use a wideband and do the following basic steps:
1. Put the correct commanded fueling values in both the "commanded fuel while in open loop" table and the "PE" table (for part throttle and full throttle respectively).
2. Put the car in Open Loop Speed Density, and using the wideband readings, bring the actual AFRs to meet the commanded AFRs by tuning the VE table first.
3. Put the MAF back on line and once again bring the actual AFRs to meet the commanded AFRs by tuning the MAF table.

The above is just a basic explaination, and there are other details (cat overtemp, DFCO, etc) that I am leaving out... hope that helps...
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Old 05-06-2012, 08:11 PM   #8
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Thanks; I have rushing this more than I should, because time is just too hard to come by right now. I think Ill just put it off a couple of weeks and start all over
The car runs GREAT part throttle, and is strong up top, but is a dog going WOT off idle. It has a stall and it still barely spins the tires. (used to melt them from a roll)
I changed the scaler only SLIGHTLY because 80% of the post and feedback I got, said leave it alone. When I did briefly change it, it would not stay running. I wonder if I should just change it and do what I need to do to get it run and see if that will help the WOT off idle
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Old 05-07-2012, 07:08 AM   #9
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[QUOTE=BOTTLE ROCKET;16280207]
Quote:
Originally Posted by BLK02WS6 View Post
Umm, yes the MAF does effect fueling at WOT if you are not in speed density... You are between 12.8 and 13.1 on a blower car? That is very lean - that is naturally aspirated AFR territory... You sure you know what you are doing here? Sounds like you may be about to learn some very expensive lessons in tuning...[/QUOTE]

Yea; Not tuning a blower car
This is my wife's H/C car that I just intalled a FAST 92/LS2 TB on.
My undertanding is that MAF is for steady airflow (crusing)and the VE table is for transition AND for a check for MAF. When the car meets the perimeters for WOT (TP and MAP) it fuels strictly by your command PE, ADDING any positive fuel trims, but ignoring (adding zero fuel) for any negative.I have read that the MAF helps fuel after WOT has been reached, but must confess that I'm not sure how since I have never tuned MAF (per the tuning guide) past 4000 rpm.
You are still wrong, the MAF will still have affect on fueling at WOT, Try it and see, Bump up your Hz in a WOT KPA and see your A/F get rich...
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Old 05-07-2012, 09:38 AM   #10
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[QUOTE=moehorsepower;16282484]
Quote:
Originally Posted by BOTTLE ROCKET View Post

You are still wrong, the MAF will still have affect on fueling at WOT, Try it and see, Bump up your Hz in a WOT KPA and see your A/F get rich...
What the Heck?? Not sure the point, but I AM tuning a NA car, not a blower car.
I was ASKING whether the MAF had an affect on WOT. Based on the tuning manuals, it would SEEM that it would not.
First; It states that the MAF reads steady airflow, and does not read transition because there is a delay, and when accelerating at WOT, there is DEFINITLY a change in airflow (not steady)
Second; The tuning guides only have you tune MAF to 4000rpm, so it would make you wonder how it would be accurate to 6500.

That being said, If you veteran tuners say it does affect it, then I am certainly not going to dispute it.
Guess I will try to tune my MAF a little higher
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Old 05-07-2012, 10:59 AM   #11
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[QUOTE=BOTTLE ROCKET;16282861]
Quote:
Originally Posted by moehorsepower View Post

What the Heck?? Not sure the point, but I AM tuning a NA car, not a blower car.
I was ASKING whether the MAF had an affect on WOT. Based on the tuning manuals, it would SEEM that it would not.
First; It states that the MAF reads steady airflow, and does not read transition because there is a delay, and when accelerating at WOT, there is DEFINITLY a change in airflow (not steady)
Second; The tuning guides only have you tune MAF to 4000rpm, so it would make you wonder how it would be accurate to 6500.

That being said, If you veteran tuners say it does affect it, then I am certainly not going to dispute it.
Guess I will try to tune my MAF a little higher
Yes, this affects N/A cars too..There are many ways to manipulate your A/F, if needed, IFR, PE, VE, MAF...or a combo of all...
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Old 05-07-2012, 02:00 PM   #12
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Since I changed from a 78 to a 90mm TB, should I change the scaler? MOST post/replys are saying no, but I wonder if it has any thing to do with the off idle, WOT performance issue.
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Old 05-07-2012, 02:13 PM   #13
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more incoming air will affect idle..Will need to adjust to be within the proper parameters..
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Old 05-07-2012, 07:36 PM   #14
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Quote:
Originally Posted by BOTTLE ROCKET View Post
I was ASKING whether the MAF had an affect on WOT. Based on the tuning manuals, it would SEEM that it would not.
First; It states that the MAF reads steady airflow, and does not read transition because there is a delay, and when accelerating at WOT, there is DEFINITLY a change in airflow (not steady)
Second; The tuning guides only have you tune MAF to 4000rpm, so it would make you wonder how it would be accurate to 6500.

That being said, If you veteran tuners say it does affect it, then I am certainly not going to dispute it.
Guess I will try to tune my MAF a little higher
Not sure which tuning guide you are talking about, but what I have always seen is to tune the VE up to 4000 rpm if you are going to put the MAF back on line (you have to tune the whole VE table if you are going SD, of course)... I think you have it backwards (i.e. VE up to 4000, whole MAF table)

You are somewhat right in what you say above about transient and steady state; however there is more to it than that - Here is some info from EFILive tuning tool regarding table B0120 {RPM threshold for airflow caculation}, it is normally set to 4000 rpm:

"If engine speed is less than this value, then the PCM uses a dynamically calculated airflow value to determine grams of air per cylinder.
While the airflow is in a "steady state", then a correction factor is updated based on the airflow difference between the MAF sensed airflow and the MAP calculated airflow.
During rapid changes in airflow, the correction factor is applied to the airflow calculations to compensate.

If engine speed is above this value, then the PCM will use the MAF sensor exclusively (if not disabled by DTCs) to calculate grams of air per cylinder.
No updates are made to the airflow correction factor."

That boils down to - PCM calculates airmass (i.e. cylinder airmass) from:
- above 4000 rpm: MAF,
- below 4000 rpm: MAF (steady throttle/airflow) and/or VE (transient throttle/airflow),
- in SD (MAF-less): VE

Keep in mind, when you mat the throttle, that is steady throttle - steady on the floor! Hope that helps...

Also, keep in mind that your issue may not be a fuel issue - or even a tuning issue at all... welcome to the wonderful world of tuning - aint it fun
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Old 05-08-2012, 06:30 PM   #15
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I checked the maual (Tuning school) and it only calls to tune the VE table AND MAF to 4000 RPMs. I guess Ill work on tuning it on up a little higher.
Wont have time to work on it before the weekend, but it is surging really bad at idle, so I added flow to the idle table and checked the scan log. It looks like the O2s are dying. They are VERY lazy, with as much as 3 seconds between oscalations somtimes
Is it really possible that BOTH sensors are going out at the same time or is there somthing else going on?
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Old 05-08-2012, 07:12 PM   #16
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Well, that manual makes no sense to me - what about above 4000 RPMs? Do they say leave that untuned? no way...

Personally, I tune the VE table all the way up to redline - that way, if the MAF ever goes out, the tune is still spot on...

If I were you, I would go back and tune the VE table first, then the MAF - like I outlined in the post above... What software are you using?
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Old 05-08-2012, 10:22 PM   #17
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And O2's are going to be lazy on a car with longtube headers. Lazy switching at idle doesn't mean they're bad.
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Old 05-09-2012, 06:12 PM   #18
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Quote:
Originally Posted by SMOKINV8 View Post
And O2's are going to be lazy on a car with longtube headers. Lazy switching at idle doesn't mean they're bad.
These are TOO lazy. I watched them many, many times and they have never been this slow and random. Not sure if they're bad or somthing else is wrong, but they are definitly not funtioning normal. The AFR never gets much ablove the 13s at idle.

BLK02

I am going to try and get some tuning in this weekend if time permits, and I will definity tune both up high.
I did a SD tune on my blown car and tuned VE to 6300 (where I shift) and after making adjustments for the Meth, it is DEAD ON.
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Old 05-10-2012, 03:05 PM   #19
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Kinda read through this quickly...so my apologies if this was already cleared up.

The 4,000 RPM threshold that keeps coming up (which BTW is something you can change) is the point where the PCM switches from a blend of MAF and MAP readings and goes to a pure MAF-based calculation. The PCM doesn't recognize forced induction, therefore it doesn't matter what your mods are. Some people (like myself) choose to alter this threshold (ex. lower it to 400rpm) and run MAF-only.

As for the car breaking up, I would log misfires, AFR, check the coil packs/plugs, and fuel pressure if possible. I would guess it's fuel or spark related.
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Old 05-19-2012, 01:55 PM   #20
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UPDATE***

I started over and tuned VE and MAF to 6400rpm.
I have eased up my BRAF and it has helped the surging (as Im sure gettng the VE dialed in did as well) and the car is strong with no miss-firing when I punch it from a roll and go through the gears
Now I have only two major issues remaining.

1. Although it is strong part throttle from idle, if I nail it from a dead stop, it is still a "dog"!!! where it used to turn the Nittos into smoke even from a roll, now it will not even turn them over. (its an A4 with 3200 stall)
2. The same issue I've had with her car for a while, when I go into forth, and the convertor locks at a lower speed (55), the car is shutttering and bucking, like the convertor is locking and unlocking quickly. Wonder if it is the actual convertor
Any thoughts?
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Old 05-19-2012, 01:55 PM
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