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yea 10% is high (lean) for idle
 

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When did you buy your sri? I got mine in december and have similar trims. 10.7 is not going to hurt anything. If it goes up to 20 then you will throw a CEL. I would contact cobb if you got the intake recently. They offered to check that mine was within spec when I called. If it is not they will replace it.
 

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certainly +10% at idle is nothing to worry about at all. it's not damaging or hurting anything.

if you had +10% fuel trims at full throttle THEN that would be something to be worried about
 

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So what are acceptable ltft at idle and WOT? I am pretty sure my idle is around -6%, but not sure about WOT. I will do a datalog and check the next chance I get.
 

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Once you hit 20 you get a CEL. I think mine were 14 with the ms cai, so I guess mazda felt that was acceptable. Within 8 of 0 is pretty good.
 

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[quote author=qwerty4550 link=topic=134342.msg2889411#msg2889411 date=1232912075]
So what are acceptable ltft at idle and WOT? I am pretty sure my idle is around -6%, but not sure about WOT. I will do a datalog and check the next chance I get.
[/quote]

0% for WOT is what you want, but without a tuner it's probably going to be +/-2-4%

Being a percent or 2 rich isn't too bad at WOT. You definitely don't want to be too lean at WOT though.
 

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[quote author=the_caruch link=topic=134342.msg2889767#msg2889767 date=1232927931]
[quote author=qwerty4550 link=topic=134342.msg2889411#msg2889411 date=1232912075]
So what are acceptable ltft at idle and WOT? I am pretty sure my idle is around -6%, but not sure about WOT. I will do a datalog and check the next chance I get.
[/quote]

0% for WOT is what you want, but without a tuner it's probably going to be +/-2-4%

Being a percent or 2 rich isn't too bad at WOT. You definitely don't want to be too lean at WOT though.
[/quote]

So when you are in the negative you are running rich, and when you are in the positive you are running lean, correct?
 

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[quote author=qwerty4550 link=topic=134342.msg2889845#msg2889845 date=1232932296]
[quote author=the_caruch link=topic=134342.msg2889767#msg2889767 date=1232927931]
[quote author=qwerty4550 link=topic=134342.msg2889411#msg2889411 date=1232912075]
So what are acceptable ltft at idle and WOT? I am pretty sure my idle is around -6%, but not sure about WOT. I will do a datalog and check the next chance I get.
[/quote]

0% for WOT is what you want, but without a tuner it's probably going to be +/-2-4%

Being a percent or 2 rich isn't too bad at WOT. You definitely don't want to be too lean at WOT though.
[/quote]

So when you are in the negative you are running rich, and when you are in the positive you are running lean, correct?
[/quote]

No. LTFT does not tell you anything about the actual fuel mixture (i.e. running lean/rich).

Rather, it is the amount of correction applied by the ECU in order to achieve the target fuel mixture for the current conditions.
 

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[quote author=GT1 link=topic=134342.msg2890691#msg2890691 date=1232957347]
[quote author=qwerty4550 link=topic=134342.msg2889845#msg2889845 date=1232932296]
[quote author=the_caruch link=topic=134342.msg2889767#msg2889767 date=1232927931]
[quote author=qwerty4550 link=topic=134342.msg2889411#msg2889411 date=1232912075]
So what are acceptable ltft at idle and WOT? I am pretty sure my idle is around -6%, but not sure about WOT. I will do a datalog and check the next chance I get.
[/quote]

0% for WOT is what you want, but without a tuner it's probably going to be +/-2-4%

Being a percent or 2 rich isn't too bad at WOT. You definitely don't want to be too lean at WOT though.
[/quote]

So when you are in the negative you are running rich, and when you are in the positive you are running lean, correct?
[/quote]

No. LTFT does not tell you anything about the actual fuel mixture (i.e. running lean/rich).

Rather, it is the amount of correction applied by the ECU in order to achieve the target fuel mixture for the current conditions.
[/quote]

So at WOT, if you have a tune you should be very close to 0 correct? However, without a tune (me) what are acceptable numbers? Also, what is the difference between STFT (short-term fuel trims?) & LTFT (long-term fuel trims)? Does LTFT avg every value it has received per cycle, while STFT just gives the actual value at that point (- refresh times)? Sorry for all of the noob questions, but I would like to know what I am actually reading with my DH :lol: .

Also, I know this is off-topic, but is there a way to log something on the DH to show if I need to tighten or loosen the screw on my BOV/BPV? I would rather use values over just listening with my ears.
 

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a few percent +/- is acceptable in my opinion at WOT

LTFT is what you want to look at, but STFT affects LTFT. It's exactly what they stand for, long term / short term fuel trims. The STFT will more than likely jump around in values rapidly. Whereas LTFT will not change as drastically.

It all relates back how much fuel the car is adding/subtracting to get the mixture to stoich 14.7a/f mixture when you are cruising around.

search google for a bunch of articles on ltft and stft, you're bound to get more info on it


as far as your BOV question you might be able to simply monitor boost pressure?
 

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[quote author=javanc link=topic=134342.msg2890737#msg2890737 date=1232960910]
Holy Smokes, GT1 is still alive! Good to see ya man.
Back to your scheduled thread. :hijacked:
[/quote]

Greetings to you javanc. :wavey:
Yes, I'm alive and I still have the MS3.
 

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[quote author=qwerty4550 link=topic=134342.msg2891896#msg2891896 date=1233010416]

So at WOT, if you have a tune you should be very close to 0 correct? However, without a tune (me) what are acceptable numbers? Also, what is the difference between STFT (short-term fuel trims?) & LTFT (long-term fuel trims)? Does LTFT avg every value it has received per cycle, while STFT just gives the actual value at that point (- refresh times)? Sorry for all of the noob questions, but I would like to know what I am actually reading with my DH :lol: .

[/quote]

LTFT is more or less derived from averaging the STFT.
The fuel trim at any point in time is the sum of the STFT and the LTFT.
For example if LTFT is +2.3 and STFT is -1.5, then the current fuel trim is +0.8

Long term fuel trims are greatly affected by intakes because it is largely a function of the MAF sensor (with feedback from the O2 sensor).

Unusually high LTFT readings may indicate a problem. If there were an air leak downstream of the MAF sensor (i.e. there is unmetered air), the ECU will compensate by richening the mixture, which will be reflected in the LTFT readings.

Also, you may have noticed that there are 4 different LTFT readings that switch depending upon the engine load.
 
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