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Old 03-08-2013, 02:43 PM   #1
mechatricity
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Default Huge AF correction in CL, very rich in OL cruise

I've been chasing this problem with my own very limited knowledge for a while and it's time to seek outside counsel.

I have a wideband, i'm protuned (on AP v1, but logging with romraider). Based on observation of my wideband and a ton of logging, i've come to a couple conclusions.

A) I have very large AF #1 correction in closed loop. Essentially it will continue to climb as RPMs increase until it switches back to open loop @ ~3k rpm

B)Idle, Cruising in 1st, 2nd, 3rd, whatever gear between idle and 2500 rpm yields an extremely rich condition, occasionally down into the low 11s on the wideband and corroborated with readings from the front O2.

Learning view shows no learned knock and no learned fueling corrections, IAM is 1. No CELs. Tried unplugging front O2, obviously sticks in OL. Recently replaced rear O2. I can cruise above 2500 RPM on the highway in 5th and fluctuate between 14-15.3 AFR, but i don't know what AF correction is doing during that time.

Low speed cruise log:
https://docs.google.com/spreadsheet/...VE&usp=sharing

another low speed cruise log:
https://docs.google.com/spreadsheet/...Gc&usp=sharing

I know there's some knock in there that has me raising my eyebrow, i don't usually see any knock but maybe these are all related. Also i realize IAM .75 in this log, i had reset my ECU slightly prior during my troubleshooting. That could be why i'm seeing more timing pulled than normal, but there is definitely a knock event there. You may also notice the knock sum is really high until it mysteriously goes to zero. Could this be indicative of a bad knock sensor? Knock seems to increment quickly at idle and low rpm cruise.
https://docs.google.com/spreadsheet/...Wc&usp=sharing

I would humbly appreciate any advice i can get. I'm planning on getting a new OS tune from AWDtuning as soon as they can get me in, but i would like to have this issue ironed out first.

Last edited by mechatricity; 03-08-2013 at 02:59 PM.
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Old 03-08-2013, 03:24 PM   #2
the suicidal eggroll
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Why is your car almost always in open loop in those logs? That's probably why your AFL is zero, it never seems to spend enough time in closed loop for AFL to change.

I see two issues:
1) Your car is almost always in open loop for no apparent reason
2) You seem to be running about 8% rich according to AFC
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Old 03-08-2013, 03:25 PM   #3
mechatricity
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Thanks for the response, i have no idea. Frankly the only range i can keep it in CL is 2500-3000 RPM unless i've got cruise control on/steady throttle input in that range. What would cause it to stick in OL like that? I was under the impression that i shouldn't be in OL until MAF flow > 50-60 g/s, that's obviously not happening here.
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Old 03-08-2013, 03:29 PM   #4
the suicidal eggroll
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I'd go back and check your CL/OL thresholds in the tune. You should be in CL from idle to around 3500 RPM or very heavy throttle. Like you said, your logs show you only dipping into CL between about 2500-2800 RPM. It's even stuck in OL at steady throttle at 2k RPM, which is weird.
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Old 03-08-2013, 03:33 PM   #5
mechatricity
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Quote:
Originally Posted by the suicidal eggroll View Post
I'd go back and check your CL/OL thresholds in the tune. You should be in CL from idle to around 3500 RPM or very heavy throttle. Like you said, your logs show you only dipping into CL between about 2500-2800 RPM. It's even stuck in OL at steady throttle at 2k RPM, which is weird.
Thanks again and thanks for confirming.

Let's assume (and this is in fact the case) that the tune hasn't been touched since it was done in 2008. Could there be a mechanical factor that would cause it to stick in OL under low load? I still seem to be getting accurate readings from the MAF and front O2. If the front O2 was borked, i assume it would stick in "warm up" (7) rather than OL?
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Old 03-08-2013, 04:23 PM   #6
mechatricity
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Also for the sake of argument, there is a stage 2 basemap on my AP that i will try to flash and see if the behavior changes at all.
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Old 03-08-2013, 04:23 PM   #7
the suicidal eggroll
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Just took another look, it's because of your fueling target. When your target is 14.7, the car is in CL, when the target is <14, the car is in OL, which is as it should be. The question, then, is why your fueling target at <2500 RPM is <14.

And the separate issue is why are you running rich. For that I'd start to look for mechanical issues, such as a boost leak.
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Old 03-08-2013, 07:34 PM   #8
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I'm having a Similar issue, I'm running speed density though. Changed my o2 sensor nothing changed. , boost leak checked it was good. Going to change my coolant temp sensor
Next. But for a/f correction I'm getting +- 25 percent.
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Old 03-08-2013, 08:24 PM   #9
mechatricity
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I know my coolant temp is reading accurately.

Is it possible that something mechanical (front O2) is causing it to go into OL, but the MAF scaling in my tune is poor at those lower flow rates, causing me to be so rich?
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Old 03-08-2013, 08:27 PM   #10
the suicidal eggroll
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Post #7 explains why you're in OL so much, it's because of the OL fueling target in your tune.
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Old 03-08-2013, 08:46 PM   #11
mechatricity
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Quote:
Originally Posted by the suicidal eggroll View Post
Post #7 explains why you're in OL so much, it's because of the OL fueling target in your tune.
which i would be completely on-board with if this tune hadn't been trouble-free for 30 or 40k miles already. Is there some inherent parameter in the ECU that can modify the OL fueling target or is it a static value?

Thanks for your help thinking this through.
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Old 03-09-2013, 02:04 PM   #12
the suicidal eggroll
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Pretty sure it's static, but you could always open the tune and look.
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Old 03-10-2013, 02:19 PM   #13
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Thats some serious timing advance, even for cruise. Great for gas mileage, but may be causing some low load knock.
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