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Old 06-17-2020, 11:27 PM   #1
STi_Future
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Default AF Correction 1 and AFR numbers are worrying me

I have an 04 STi I just recently rebuilt with a forged motor and a lot of mods a lot of which will affect AFR and how the car runs. I know these can cause issues without a tune, I have a base map from a tuner for now until I can get over there for a pro tune. I know that because it is on a base map the AFR and corrections wonít be perfect because they arenít dialed in like they will be with the pro tune Iím just worried.

Now for the numbers, for the last few days I have been noticing that my AFR always stays around 13-14.7 and that is at cruising speed and idle. When idling it stays closer to 14.7 usually. My correction is anywhere from -.78/.78 to -7/7 or so when idling after start up, when I idle after driving for a while it will stay around -.78/.78 to -7/7 for a bit then slowly rise up anywhere from -10/10 to -15/15 and will stay there for a bit and the AFR will remain around 13 to 14.7.

Now when cruising my correction 1 is at -5/5 or around there. When I let off the throttle for a few seconds and let the car slow itself down a bit then get back on the throttle like I was before I let off then the correction 1 jumps up to around -9/9 to -14/14 and the AFR goes down to 13.5 or around there. It will stay at that high correction for about 12 to 15 seconds and go back down to -5/5 correction and the AFR goes back to around 14.7.

I havenít gone WOT yet as it is not fully pro tuned but I have given it a few good pulls and the AFR does what it is supposed to do and goes down to about 11 on the AP (I know itís not wide band). It gets richer with power and doesnít lean out when I push it which is good.

I have had the car boost leak and vacuum leak tested twice in the last month or 2 as I am worried about the car. The tests always come back perfect on both. Which begs the question, are these numbers ok? Iíve read that cobb says correction 1 should be around -8/8 for EJ motors and mine deviates from that quite often.

Please ask any questions you need to know.

Thank you in advance!
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Last edited by STi_Future; 06-17-2020 at 11:39 PM.
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Old 06-17-2020, 11:54 PM   #2
Jersey Man10
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Looks normal tbh. The numbers fluctuate a lot it seems.
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Old 06-18-2020, 04:22 AM   #3
bobjr94
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Don't worry about the numbers when you let off the throttle, it always goes rich for a second, making the af correction spike for a second also. If it's normally around +5 / -5 when crusing that is really good for base map. Even a pro tune won't be at 0, variations in fuel, temperature, altitude, air filter new / dirty will all effect fuel trim.

Idle and light throttle should be 14.4-14.7, depending on the tune after about 3-5lbs of boost should drop it under 13, going to 12 and 11 by full boost. But yes the onboard AF sensor isn't accurate under high boost, it may say 11 but could be anywhere from 9-12.
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Old 06-18-2020, 07:40 AM   #4
STi_Future
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Quote:
Originally Posted by bobjr94 View Post
Don't worry about the numbers when you let off the throttle, it always goes rich for a second, making the af correction spike for a second also. If it's normally around +5 / -5 when crusing that is really good for base map. Even a pro tune won't be at 0, variations in fuel, temperature, altitude, air filter new / dirty will all effect fuel trim.

Idle and light throttle should be 14.4-14.7, depending on the tune after about 3-5lbs of boost should drop it under 13, going to 12 and 11 by full boost. But yes the onboard AF sensor isn't accurate under high boost, it may say 11 but could be anywhere from 9-12.


Iím not worried about the numbers when I let off the throttle Iím worried about the correction jumping up for 15 seconds when I get back on the throttle.

Idle is normally around 14.4-14.7 but the correction will randomly rise to about 10-15 correction for around a minute before it drops. Iím worried something bad is causing it to do that.
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Old 06-18-2020, 07:50 AM   #5
wrxlaunch
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so its pulling fuel as its supposed to when you get back on the throttle... whats the problem? what size injectors do you have?
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Old 06-18-2020, 11:22 PM   #6
Jersey Man10
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The AP isn't THAT accurate which is why you see that jump. You need a wideband to get a proper reading. Your numbers are normal.
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Old 06-25-2020, 10:43 PM   #7
BeastianSTI
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OP, are you on speed density?

Also, if you're just on a base map, it seems reasonable that the tuner hasn't fully dialed in the closed-loop fueling maps (VE/MAF). There are a lot of interesting compensation tables that can come into play too when the car gets hotter.

An exhaust leak could also cause some odd AF correction numbers too. I saw you did a boost leak/vacuum leak test, but I am curious if you tried a smoke test of the exhaust system.
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Old 06-26-2020, 02:18 AM   #8
benflynn
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Zero out ol-cL delay, add some fuel to ur ol map and pull a couple degrees timing, u will be good till tune
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