How closely should AFRs be monitored when not WOT? - Page 2 - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Synack · 06-05-2014, 02:23 PM

have you unplugged your battery recently? I had this issue 8 months ago when I pulled my battery and started it after putting it back in. The ECU has to relearn its trim levels and can take up to 50 miles to get back to normal.

post_break · 06-05-2014, 02:25 PM

Quote:

Originally Posted by Synack

have you unplugged your battery recently? I had this issue 8 months ago when I pulled my battery and started it after putting it back in. The ECU has to relearn its trim levels and can take up to 50 miles to get back to normal.

Nope, it had at least 500 miles since the last battery pull. Yesterday I unplugged it to see if the trims were just bad and it's still doing it.

wparsons · 06-05-2014, 02:42 PM

Pull a log with what Nelson (nelsmar) suggested to see what the commanded AFR is. If the tune is asking for a high AFR you can fix it if you really want, if it's requesting low and just lagging a bit in response there's nothing you can do unless there is something else at fault (leak, bad sensor, etc).

IIRC, pulling the battery doesn't reset the trims either, you have to do a fresh flash to reset them.

kiichiro · 06-05-2014, 03:12 PM

If it's not under load no worries

DeliciousTuning · 06-05-2014, 07:12 PM

Quote:

Originally Posted by post_break

I have the kraftwerks supercharger and have been noticing some odd AFR behavior. Or at least odd to me, could be completely normal.

So when accelerating from a light, using pretty much the bare minimum of throttle to let the rpms climb, in third gear around 3,200-4,200 I've noticed my AFR dip into the 15's. It's happened quite a few times and I'm curious as to if that's just being paranoid and it's nothing to worry about since I'm obviously not harping on the car. It's usually only under load too, if I'm trying to "push" the car and gain momentum, like if you're just maintaining speed and want to go faster they rise to the 15's then go back down.

At WOT it never touches that range, and is in the 11's where it should be. Am I just babying the gas pedal too much? Tuning issue? I'll try to get logs if needed.

The only time you would really need to worry if it is running lean under cruising conditions is if it is causing the engine to knock. This can lead to engine failure, though I highly doubt this is the case.

As for what might be going on, you may want to take a look at your long term fuel trims and see what they are doing. You might see some crazy swings to rich or lean almost randomly, this can cause the AFR ratios to do just like you have stated. We have seen this happen more so on forced inductions vehicles, depending on how they are calibrated.

Cheers,
William Knose
Delicious Tuning

post_break · 06-05-2014, 07:18 PM

Quote:

Originally Posted by DeliciousTuning

The only time you would really need to worry if it is running lean under cruising conditions is if it is causing the engine to knock. This can lead to engine failure, though I highly doubt this is the case.

As for what might be going on, you may want to take a look at your long term fuel trims and see what they are doing. You might see some crazy swings to rich or lean almost randomly, this can cause the AFR ratios to do just like you have stated. We have seen this happen more so on forced inductions vehicles, depending on how they are calibrated.

Cheers,
William Knose
Delicious Tuning

I'll take a look at the fuel trims. I'm going to log that extra data like neslmar recommended too. I hope you got my email with the updated dongle ID, your website sent me a confirmation email but threw an error when I hit submit. Sorry again for screwing up the MAP sensor info last time.

Mapping it our you're spot on. My long term fuel trims are going nuts. And the sensor is seeing 15 AFR and using the trims to bring it back down.

Attached logs with requested parameters.

wparsons · 06-06-2014, 11:13 AM

FYI, you can share logs easier by uploading them to datazap.me

I don't have anything to open them with at work, but I'm sure someone will take a look before I'm home!

post_break · 06-06-2014, 11:18 AM

Quote:

Originally Posted by wparsons

FYI, you can share logs easier by uploading them to datazap.me

I don't have anything to open them with at work, but I'm sure someone will take a look before I'm home!

That site is amazing! http://datazap.me/u/postbreak/kraftw...t?log=0&data=5

wparsons · 06-06-2014, 02:51 PM

Yep, sure is! SO handy.

post_break · 06-10-2014, 10:36 PM

So after clamping the evap hoses under the intake my AFRs went back back down. Here is an updated log.

http://datazap.me/u/postbreak/kraftw...i-93-flex-fuel

06-05-2014, 02:23 PM	#15
Synack Boosted Join Date: Jul 2012 Drives: Sideways Location: Atlanta Georgia USA Posts: 2,377 Thanks: 388 Thanked 716 Times in 414 Posts Mentioned: 25 Post(s) Tagged: 0 Thread(s)	have you unplugged your battery recently? I had this issue 8 months ago when I pulled my battery and started it after putting it back in. The ECU has to relearn its trim levels and can take up to 50 miles to get back to normal. __________________ *Nismo 370Z 300whp -> FR-S Turbo 450whp on E85 -> Z06 Corvette 500whp*

06-05-2014, 03:12 PM	#18
kiichiro corolla specs/GTR looks Join Date: May 2013 Drives: ooh oooh pretty tail lights Location: slower than a accord V6 Posts: 490 Thanks: 229 Thanked 113 Times in 79 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	If it's not under load no worries __________________ SOLD THEM BOTH Hers: 2007 987S Mine: 2012 991S That was fun, thanks Hachi

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