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Old 01-27-2009, 07:41 PM   #1
GARFIELD
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Default Leaning out issue

Hey guys,

I've been having a problem with my 2004 JDM STI and hope you can assist. My mods are as follows:

Deadbolt TD06 20G turbo
820 cc modified stock WRX injectors (Witchhunter.com)
Walboro fuel pump
XS Power FMIC
Full Ebay Exhaust
Open source ECU tune (tactrix)

The car has been tuned for AFR's in the low 11's @ WOT. The problem i'm having is that after 3 days or so of driving the AFR's start to lean out into the low 12s @ WOT. If the ECU is reset, the AFR's go back to low 11's and gradually lean out again. The car has been retuned about 4 times (scaling and rescaling the injectors while trimming the fuel map still keeping the AFRs in the low 11's), checked the fuel pump and changed the fuel filter, but the same thing still happens after 3 days of driving.

Any assistance would be greatly appreciated?
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Old 01-27-2009, 07:51 PM   #2
wrspeed
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do you know what are the values on your open loop table under full load ?
i seen cars with low 12 afr tagets on that table and the ecu actually doing what it is ask.
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Old 01-28-2009, 07:39 AM   #3
gabedude
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Use the Romraider MAF tool and get your D range LTFT (AFL) to be around 0. The car is leaning out due to thinking that it is running too rich while in closed loop at moderate loads. This D range affects open loop fueling. Resettign the ECU resets the long term fuel trims.
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Old 01-28-2009, 11:08 AM   #4
GARFIELD
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Quote:
Originally Posted by gabedude View Post
Use the Romraider MAF tool and get your D range LTFT (AFL) to be around 0. The car is leaning out due to thinking that it is running too rich while in closed loop at moderate loads. This D range affects open loop fueling. Resettign the ECU resets the long term fuel trims.
Thanks. I'll ask my tuner to try that and let you know the results.

I should also point out that when the injectors are scaled all the way (i.e. telling the ECU that the injectors are 820cc), the leaning out issue does not arise. The car in fact held the correct ratios for over a week until I started to get a "system lean" check light when I'm cruising. It would come on for a few minutes then go off. It never came on at WOT. Shortly after I started getting the system lean check light, the AFR's suddenly became very rich (high 9's to low 10's). The injectors have been scaled by telling the ECU that they are 560cc, 680cc and 750cc, but in each instance, the leaning out issue still arose.
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Old 01-29-2009, 08:00 AM   #5
eminehart
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Like others have said it is probably a Maf scaling issue. There is probably some problem around 40-50 g/sec. Properly scaling this area could keep AF from getting out of wack.

To help keep this type of situation from happening I like to keep A/F Learning D from moving much by raising the minimum value up to at least 50g/sec. It seems to keep that value from moving much. Closed loop is the only thing that effects A/F learning so if its at the tail end or even out of CL you will not get this kind of learning.
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Old 01-29-2009, 08:20 AM   #6
GARFIELD
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Thank you. I'll let y'all know how it goes.
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Old 02-04-2009, 12:33 PM   #7
GARFIELD
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Quote:
Originally Posted by gabedude View Post
Use the Romraider MAF tool and get your D range LTFT (AFL) to be around 0. The car is leaning out due to thinking that it is running too rich while in closed loop at moderate loads. This D range affects open loop fueling. Resettign the ECU resets the long term fuel trims.
Stock, my D range LTFT (AFL) is 50g/sec. My tuner didn't feel comfortable moving that all the way to 0, so he moved it to 25 to see how the car would respond. The car actually leaned out faster than it did before after this change. Bear in mind that it is at WOT that the car leans out. When cruising, the AFR's are in the 14's as is customary.

I'm getting really frustrated now. Any other suggestion anyone?
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Old 02-04-2009, 01:49 PM   #8
Phatron
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Quote:
Originally Posted by gabedude View Post
Use the Romraider MAF tool and get your D range LTFT (AFL) to be around 0. The car is leaning out due to thinking that it is running too rich while in closed loop at moderate loads. This D range affects open loop fueling. Resettign the ECU resets the long term fuel trims.
Garfield, you mis-read and/or mis-interpereted Gabe's post. He said you want the D Range correction value to be around zero, NOT the Minimum D Range g/s value.


Quote:
Originally Posted by GARFIELD View Post
Stock, my D range LTFT (AFL) is 50g/sec. My tuner didn't feel comfortable moving that all the way to 0, so he moved it to 25 to see how the car would respond. The car actually leaned out faster than it did before after this change. Bear in mind that it is at WOT that the car leans out. When cruising, the AFR's are in the 14's as is customary.

I'm getting really frustrated now. Any other suggestion anyone?
It seems that your tuner really doesnt know what he's changing if he actually lowered that value. Lowering the D Range down to 25 g/s will just make it more volatile, which you saw since it changed faster.

I have my D-Range minimum g/s raised up to 80 g/s on both my wrx and STi.

This basically locks the D-Range Correction to 0%, which is what I wanted and why i did it. I had it at 70 g/s, but actually stayed in CL up there are got a D Range value, so i raised it to 80 g/s.

Quote:
Originally Posted by GARFIELD View Post
The car has been retuned about 4 times (scaling and rescaling the injectors while trimming the fuel map still keeping the AFRs in the low 11's), checked the fuel pump and changed the fuel filter, but the same thing still happens after 3 days of driving.

Any assistance would be greatly appreciated?
Have you also checked for post MAF pre-turbo leak? This will cause you to run lean.


Also, the easiest way for us to help you here is to

1) Host your ROM somewhere so we can look at it

2) Post logs of your A, B, C, D fuel trims after several days of driving
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Old 02-04-2009, 01:56 PM   #9
GARFIELD
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Thanks for the clarification Phatron. I'll try again and let you know how it goes.

G.
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Old 02-09-2009, 05:59 AM   #10
GARFIELD
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Moving my D-Range minimum g/s up to 80 g/s did not solve the issue (I moved it back down to the stock 50 g/s).

The car now leans out much faster than it did when it was first tuned.

I checked for a leak as you suggested, but there is none. I tried other injectors to see if that was the problem but it leaned out just the same.

Any other suggestions?
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Old 02-09-2009, 06:30 AM   #11
wrspeed
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p'med sent
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Old 02-09-2009, 08:57 AM   #12
eminehart
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The modded stock injectors generally have a scaling around 830 this is why you weren't getting the leaning out issue. The biggest issue is the latency on those. With stock latencies you will see about a 40% correction at idle. You need to up the latencies significantly. To get those to behave. Sometimes a combination of latency and maf scaling is needed. When you get that correct you will no longer have this issue.

If you can post your rom we can see where your issue is.
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Old 02-09-2009, 11:48 AM   #13
Phatron
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Quote:
Originally Posted by GARFIELD View Post
Moving my D-Range minimum g/s up to 80 g/s did not solve the issue (I moved it back down to the stock 50 g/s).

The car now leans out much faster than it did when it was first tuned.

I checked for a leak as you suggested, but there is none. I tried other injectors to see if that was the problem but it leaned out just the same.

Any other suggestions?
did you reset the ECU to clear the fuel learning? maybe the D range correction stayed in there after you moved it up to 80?

Theres only a couple things that can be happening here

1) D Range learning is causing this

2) You have a leak

3) Your boost is now falling off at higher rpm and thus your load is decreasing more thus your AFR is leaning out.


Based on your original description of the problem it simply has to be #1. A leak should be present all the time and wont go away with an ECU reset.....same for a boost issue.
The D learning range does get reset with an ECU reset though. Which perfectly fits with your description. I really dont know what else it could be.

Quote:
Originally Posted by GARFIELD View Post
The car has been tuned for AFR's in the low 11's @ WOT. The problem i'm having is that after 3 days or so of driving the AFR's start to lean out into the low 12s @ WOT. If the ECU is reset, the AFR's go back to low 11's and gradually lean out again.
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Old 02-09-2009, 06:41 PM   #14
nj1266
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The car has a stock intake, so why are people suggesting that he re-scale the MAF!!! It is clearly an injector issue.

Your tuner needs to scale the injectors properly and set the latencies properly. When the injectors are poorly scaled, then your fuel trims will drift over time and that will make your AFR vary during WOT operation. To avoid that, you need to keep your LTFT as close to zero as possible.
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Old 02-09-2009, 08:27 PM   #15
Phatron
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where did he say he has a stock intake?

well.....his injectors may need to be rescaled, BUT for the WOT portion of the D Range simply upping the MAF g/s range will prevent the WOT AFR ever being effected by fuel trims.....thus will be safer and stay at 11:1 until the injectors can be correctly dialed in.

I wasnt telling him to rescale the MAF, just to up the started point of the D-Range.

Garfield,

Post your rom somewhere or at least the MAF scale, injector size and latency.
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Old 02-10-2009, 12:21 AM   #16
nj1266
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I would think that had there been an aftermarket intake, then he would have mentioned it in his list of mods. In the list there is no mention of an intake, unless there is one and he did not mention it.

To the op, do you have a stock intake?
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Old 02-10-2009, 01:55 AM   #17
Phatron
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well, im pretty sure the FMIC pipe goes right through the hole where the stock intake gets air from the fender well.

i dont think i've ever seen a FMIC kit that retains the stock airbox....

and dont forget, even if he retained the stock maf housing and just slapped on a cone filter he will most likely need to change the MAF scale.

since our maf isnt actually measuring ALL the air flowing in the tube, but rather estimating it based on flow through the middle of the tube it greatly matters HOW the air flows passed the MAF sensor.
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