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Rattling when accelerating from stop

Old 05-22-2019, 10:21 PM
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nonlinearedits
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Rattling when accelerating from stop

Hey guys I have a 2010 G37x sedan with some mods and a tune. Berk HFC being one of the mods not sure if thatís relevant to this sound. But from a complete stop, I sometimes get this weird rattling sound that lasts a second or two and goes away. No engine/trouble codes found and watching the EcuTek app I donít see any ignition timing correction happening that I would assume to be happening with a ping. Oil pressure is 27psi @ 175degrees however Iíve seen it drop to 10psi when itís hit 220+ degrees. Video attached.


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Old 05-23-2019, 12:36 AM
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Been having the same issue. Im tuned on ecutek as well and dont notice anything out of the ordinary.
Theres another larger thread discussing this issue but it really seems most people there just lived with it and no one ever really found a fix for it, and there wasn't any ill-effects on the car itself even with some people driving with this issue for 1000s of miles.
It does seem as most people noted this as heat sheilds or other rattling under the car but I doubt that since people in the thread had test pipes with this issue as well.
Your oil pressure readings do offer some new insight though.
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Old 05-25-2019, 03:28 PM
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Maybe your BERK is toasted... Mine one was making all kind a sounds... and then, I had to cut my mid pipe in half to retrieve it...
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Old 05-26-2019, 09:46 PM
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Could be the ignition correction sensitivity needs to be adjusted. Feel free to log all the knock sensor data and send it to me, I'll take a look.
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Old 05-26-2019, 10:07 PM
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Well when I started hearing this noise, I flashed back to a base just to make sure it wasn't the tune itself and eliminating another factor.
The noise continued even on base. So something is up somewhere else perhaps?
Other people have had this noise as well and aren't tuned.
Ill list off a few things that everyone experiencing this particular noise has in common.
-Only happens when car is fully warmed up
-Doesn't happen in P or N while revving or anything even in the same RPM area where the sound normally happens
-Can only happen in gear from a stop and happens around ~1000-1500RPM
-Lugging the car around in gear at the same RPM where it happens while its already moving also doesn't reproduce the sound
-No driveability issues reported other than just the noise itself.
I've been really stumped as to what it could be.
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Old 05-26-2019, 10:22 PM
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Originally Posted by bythabay View Post
Could be the ignition correction sensitivity needs to be adjusted. Feel free to log all the knock sensor data and send it to me, I'll take a look.
Thank you!!! I took logs when I heard it last but realized I did it from the dashboard and only logged what was displayed. It went away for two days then came back. Iíll log it the next time the sound starts again. That will let me make some use out of my new tablet mount 🤣
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Old 05-26-2019, 10:48 PM
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Originally Posted by Bommerang View Post
Well when I started hearing this noise, I flashed back to a base just to make sure it wasn't the tune itself and eliminating another factor.
The noise continued even on base. So something is up somewhere else perhaps?
Other people have had this noise as well and aren't tuned.
Ill list off a few things that everyone experiencing this particular noise has in common.
-Only happens when car is fully warmed up
-Doesn't happen in P or N while revving or anything even in the same RPM area where the sound normally happens
-Can only happen in gear from a stop and happens around ~1000-1500RPM
-Lugging the car around in gear at the same RPM where it happens while its already moving also doesn't reproduce the sound
-No driveability issues reported other than just the noise itself.
I've been really stumped as to what it could be.
I've resolved this issue for a few customers with knock sensitivity adjustment. There's an easy way to check using a modified base rom.
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Old 05-27-2019, 12:05 PM
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Hereís a log of it happening three times and I tagged it as it was happening each time.
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File Type: csv
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Old 05-27-2019, 12:18 PM
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Originally Posted by nonlinearedits View Post
Here’s a log of it happening three times and I tagged it as it was happening each time.
Looks like some knock to me. Keep in mind the logging rate is slower with the hardware cable and faster with the bluetooth. Even with the faster logging rate, some knock events that are picked up by the ecu are missed in the logging. Here is a sample visualized from your log that shows a knock event occurring below the threshold, but lightly skimming it. Typically these types of events are real knock events and the threshold should be made more sensitive to have the ecu pull more timing. Oficially speaking, a stand-alone knock detection device such as the Plex Knock Monitor should be used to confirm knock, but you can get great results by using the data from the logs over large data sets.
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Old 05-27-2019, 12:26 PM
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nonlinearedits
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Originally Posted by bythabay View Post



Looks like some knock to me. Keep in mind the logging rate is slower with the hardware cable and faster with the bluetooth. Even with the faster logging rate, some knock events that are picked up by the ecu are missed in the logging. Here is a sample visualized from your log that shows a knock event occurring below the threshold, but lightly skimming it. Typically these types of events are real knock events and the threshold should be made more sensitive to have the ecu pull more timing. Oficially speaking, a stand-alone knock detection device such as the Plex Knock Monitor should be used to confirm knock, but you can get great results by using the data from the logs over large data sets.
Yikes. I did do the logging via Bluetooth, should I not be driving until this gets fixed?
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Old 05-27-2019, 12:44 PM
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Originally Posted by nonlinearedits View Post
Yikes. I did do the logging via Bluetooth, should I not be driving until this gets fixed?
Many engines can operate with some amount of light detonation/knock for a very long time without any damage to the engine, this is usually done to increase fuel economy and improve power as the knock limit is where you will make the best power from the fuel assuming the engine is knock limited. Nissan does set their engines up to knock a bit more than I prefer, so I would say you're probably fine leaving it until it gets addressed. That's the beauty of doing a custom tune, is that you can customize the engine to behave/sound the way you want. Me personally, I don't like to hear my customer's engines knock it just bothers me, even if it's just slightly more efficient, it is generally better for the engine not to knock/detonate. I'd rather have it run smoother and quieter so I take a degree or two off where needed.

Another way to evaluate the situation is to look at what the ecu wanted to do if the car wasn't tuned and compare it to what it's actually doing. Here you can see the calculated timing (what the ecu would normally do) vs the actual timing your tuner set. It's clear that too much advance has been requested so an adjustment might be recommended.
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Old 05-27-2019, 01:09 PM
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Originally Posted by bythabay View Post
Many engines can operate with some amount of light detonation/knock for a very long time without any damage to the engine, this is usually done to increase fuel economy and improve power as the knock limit is where you will make the best power from the fuel assuming the engine is knock limited. Nissan does set their engines up to knock a bit more than I prefer, so I would say you're probably fine leaving it until it gets addressed. That's the beauty of doing a custom tune, is that you can customize the engine to behave/sound the way you want. Me personally, I don't like to hear my customer's engines knock it just bothers me, even if it's just slightly more efficient, it is generally better for the engine not to knock/detonate. I'd rather have it run smoother and quieter so I take a degree or two off where needed.

Another way to evaluate the situation is to look at what the ecu wanted to do if the car wasn't tuned and compare it to what it's actually doing. Here you can see the calculated timing (what the ecu would normally do) vs the actual timing your tuner set. It's clear that too much advance has been requested so an adjustment might be recommended.
I cant thank you enough for this info. Do you have a company or do you just do tunes on the side?
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Old 05-27-2019, 01:11 PM
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Originally Posted by nonlinearedits View Post
I cant thank you enough for this info. Do you have a company or do you just do tunes on the side?
My shop is infiniticare.com - I am an ecutek master tuner in Northern California, I specialize in the remote tuning of all 3.7L powertrains.
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