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Old 06-10-2019, 08:01 PM   #1
KCRS01
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Default Dam drop and feedback knock...

I'm a little worried as my dam dropped to 0.625 then went to 0.688 quickly and feedback knock of - 7.00 but fine knock is 0.00 as i did a pull at 90km/h to 120km/h at 4th gear or 3rd (cant remember) . What could be the cause of this?

A/f learning is -0.78/3.12%
Boost -10.77/16.73psi
A/f ratio 1 11.03/20.44
Pro tuned

It dropped before but without feedback knock cause of bad gas.
Also seems to consume little amount of oil when high boost

Mods:
Intake
Inlet
Tomei m8265 turbo
Downpipe/upipe
Id1000
Aeromotive fpr
Dw65c fuel pump
Built internals
91 oct
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Last edited by KCRS01; 06-11-2019 at 10:36 AM.
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Old 06-11-2019, 12:38 PM   #2
JSR84
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Drive it gently for a few days and see if the DAM comes back up, watch for low load Feedback knock and any areas where it's learned. It comes back up, get a data log in third, default parameters will do. If you notice any knock above 1.4, or if it doesn't taper off right away bail out of the pull.
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Old 06-12-2019, 07:48 PM   #3
KCRS01
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Quote:
Originally Posted by JSR84 View Post
Drive it gently for a few days and see if the DAM comes back up, watch for low load Feedback knock and any areas where it's learned. It comes back up, get a data log in third, default parameters will do. If you notice any knock above 1.4, or if it doesn't taper off right away bail out of the pull.
I resetted the ECU and drove it for a little time and it hasnt drop yet. I'll try and update this. I'll give it a few gentle driving before trying a pull
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Old 06-12-2019, 08:03 PM   #4
Waddlz
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resetting the ECU when you have a DAM drop isn't smart.

the car has learned to pull timing to protect itself, and now you have reset all that. If there is an issue you just mask it resetting the ECU.

If this were me, I'd be driving it carefully due to some bad gas(probably). but if DAM drops again, Don't reset the ECU
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Old 06-12-2019, 08:22 PM   #5
JSR84
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Disregard
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Old 06-12-2019, 09:24 PM   #6
KCRS01
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I didnt actually planning to reset it but i took out the negative terminal and worked on it because the turbo inlet looked like it was about to fall off because of how greasy it was.... I wont reset it if it does drop again. But im not seeing any feedback or fine knock so far
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Old 06-14-2019, 12:18 PM   #7
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Quote:
Originally Posted by KCRS01 View Post
I didnt actually planning to reset it but i took out the negative terminal and worked on it because the turbo inlet looked like it was about to fall off because of how greasy it was.... I wont reset it if it does drop again. But im not seeing any feedback or fine knock so far
ah i see. I thought you reset it from the Accessport.
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Old 06-14-2019, 08:14 PM   #8
KCRS01
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i dont know if this might cause dam drop or if its even a leak but after the dam drop the car have been hunting idle like crazy during cold start. it wouldnt stay still in high rpm. AF Learning 1 is between -3 to 0.78. when fully warmed up its totally fine. Does that indicate a boost or vacuum leak?
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Old 06-17-2019, 11:56 AM   #9
Waddlz
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not usually.

when you reset the ECU, all the learned values for starting are gone. so the car has to relearn them over a period of time.

Usually vacuum leaks will cause your AF Learning to sway very high in the negatives. Anything above -10 is usually a sign you have a leak, but not always.
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Old 06-17-2019, 08:45 PM   #10
Long Nguyen
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any mechanical part rubbing against each other?
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Old 06-17-2019, 09:12 PM   #11
KCRS01
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Originally Posted by Waddlz View Post
not usually.

when you reset the ECU, all the learned values for starting are gone. so the car has to relearn them over a period of time.

Usually vacuum leaks will cause your AF Learning to sway very high in the negatives. Anything above -10 is usually a sign you have a leak, but not always.
Yeah thats what i figured... I'll keep updating. Sometimes my af learning fluctuates im thinking it has to do with temperature droping then going very high. I live in Canada

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any mechanical part rubbing against each other?
Actually i hear a like heatshield rubbing sound on declaration only. I havent pinpoint the exact location but it sounds similar to that
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Old 06-17-2019, 09:21 PM   #12
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Originally Posted by KCRS01 View Post
Yeah thats what i figured... I'll keep updating. Sometimes my af learning fluctuates im thinking it has to do with temperature droping then going very high. I live in Canada







Actually i hear a like heatshield rubbing sound on declaration only. I havent pinpoint the exact location but it sounds similar to that


I too have had 2-3 occasions where knocks appear so randomly, usually big knocks, big enough to lower DAM and mostly under ramping boost.

100% of the times I found some exhaust parts rubbing the subframes.
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Old 06-19-2019, 12:01 PM   #13
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I ran into an issue with DAM drop for the first time a couple weeks ago. It actually happened about 3 days before I got the car protuned. I am only accessport and cai so nothing major at all. Not sure where the weather is like where you are but after describing exactly how it happened to my tuner he said it could easily be an issue with high intake temps. A once in a while thing isn't a big deal. I'd get worried if it happened more frequently. So far after tuning my car has been perfectly fine on DAM and fine knock learn/feedback knock don't have any significant numbers either
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Old 06-19-2019, 11:25 PM   #14
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Originally Posted by tcoled91 View Post
I ran into an issue with DAM drop for the first time a couple weeks ago. It actually happened about 3 days before I got the car protuned. I am only accessport and cai so nothing major at all. Not sure where the weather is like where you are but after describing exactly how it happened to my tuner he said it could easily be an issue with high intake temps. A once in a while thing isn't a big deal. I'd get worried if it happened more frequently. So far after tuning my car has been perfectly fine on DAM and fine knock learn/feedback knock don't have any significant numbers either
Thanks for sharing that, afaik the car got protuned by previous owner. And yeah probably since im running a cobb intake with no box but also i dont monitor intake temp.... Im planning to get a tune if i do keep the car but atm im leaning more towards getting a honda lel

Quick Update: Car still hunts for a few secs on cold start but not as bad i guess ecu starting to learn. Also dam havent drop since, no
Feedback knock except for downshift -1.4 and no fine knock.

A/f learning 1 tho fluctuates from -7 to 0.78 hopefully driving it more makes it learn better
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Old 06-23-2019, 02:47 PM   #15
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Just a quick question.

Like my A/f Learning 1 was already doing good than before like -3 to 0.78 and even better sometimes but sometimes its gets higher and higher but not more than -10/+10... does that tell something? or something to of concern. Does weather affects it? engine temperature?
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Old 06-23-2019, 07:27 PM   #16
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Weather/climate/environment can absolutely affect how the engine runs and performs. However, let's say your engine is otherwise running in tip-top shape. Weather would not generally affect it to the point of causing these issues. If it is, you (obviously) have some problems.

Have you checked/cleaned MAF? I had similar issues a few weeks ago. A new MAF sorted (most of) my problems out. I had no CEL's or anything of the sort. Started noticing a slight anomaly through monitors on my AP.
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Old 06-25-2019, 07:24 AM   #17
KCRS01
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I did clean the MAF weeks ago but not the cone filter. It is still the original maf i believe.
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Old 06-25-2019, 12:48 PM   #18
KCRS01
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Originally Posted by KCRS01 View Post
I did clean the MAF weeks ago but not the cone filter. It is still the original maf i believe.
Okay guys... The car is feeling slow like no power and af learning 1 is just going up and up when applying gas its at -8 then at idle its at -14 now....
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Old 06-25-2019, 12:51 PM   #19
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that seems like a boost leak.

what is your commanded AFR and actual AFR under boost?
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Old 06-25-2019, 06:59 PM   #20
KCRS01
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Originally Posted by Waddlz View Post
that seems like a boost leak.

what is your commanded AFR and actual AFR under boost?
What parameter i look into the accessport for commanded afr?

Hacent boosted the car yet as im driving it like a baby. But afr is 11.03 to 20.56. The car also seems to backfire now. No rough idle so far
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Old 06-25-2019, 10:36 PM   #21
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Quote:
Originally Posted by KCRS01 View Post
I did clean the MAF weeks ago but not the cone filter. It is still the original maf i believe.
Like mentioned above, pretty sure you got a leak somewhere, and since you just cleaned your maf, check the o-ring and make sure it's seated in firmly.

Here's what happened to me (twice) not saying it's exactly it but maybe something to go on. I'm on a Torqued Performance Cobb intake Stage 1 tune, I've got 155K on the clock now and it still rips pretty well.

Both events were "light load knock" which bombed my IAM down to 0 as I was going up a hill and needed to lean on the waste gate at highway speed.

First time, the original o-ring on my maf was split clean through. When I took it out it actually fell off. I ended up having an o-ring that was really close, so I used that until my new maf came. The original had 115K miles on it.

Second time; I'm not really sure of the exact cause, but I let the Cobb filter get pretty dirty, and figured it was time to clean it. When I went to take it off, the clamp that holds the filter on either worked it's way almost completely loose, or I didn't tighten it down well enough last time I changed it. While that's pre-maf, it still probably wasn't good.

At any rate, filter cleaned and all clamps tightened, the issue has yet to return after 3 tanks of gas. It could have also been "bad gas" but that just seems so rare these days.

Good luck!
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