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Discussion Starter #1 (Edited)
So, my car recently started making a misfiring sound coming from the engine. I don't know what is causing it. I have changed the spark plugs (gapped properly) and changed the fuel rail and injectors.

A while ago I did have a boost leak and that is when this sound started happening. I since fixed the boost leak issue and it still happens, but it only happens when I go WOT at this point. I can still daily my car as long I don't push it. Any suggestions?

https://youtu.be/UyD82HswqaQ
 

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Discussion Starter #3

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Well thats what I would point the finger at first. Throw the stocker back in there and see if it's fixed. If it's still doing it maybe a fuel pressure/volume issue with your new fuel rails.
 

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Discussion Starter #6
Well thats what I would point the finger at first. Throw the stocker back in there and see if it's fixed. If it's still doing it maybe a fuel pressure/volume issue with your new fuel rails.
I changed the Fuel rail and injectors because of this issue. So, I don't think they are the problem. Same thing happens even after i changed the fuel rail and injectors.

Still have your stock ecm?
I do have my stock ECU, I opted for a second ECU when getting the tune.
 

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Discussion Starter #8
Side note: Your car is crazy nice!!
Thank you vthe5th. A lot has gone into it. I still have many more to go in just not going to install them until I get this issue fixed first.
 

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I just watched your video. That sound your hearing is severe spark knock/detonation...whatever you want to cal it. I assume you have 93 octane as well?

That is the worst sound you can hear in a forced induction car. Let off the throttle if you hear it again. Not enough fuel is what's happening. You can pop the top of a piston off like that. Still think it's your tune.
 

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Check the spark plugs and make sure they are in good shape. If you've been running with the tune for over 2 years without getting these issues, you'd need to start looking at some mechanical causes. Yet didn't you have similar problem about few months ago with some bad batch of gas?
I would never push the car with those sounds in the first place. You are damaging it.
 

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That is detonation... I had it happen to me with a BTR stage 2 tune... Pull your spark plugs and look at the ground electrode. If you see little nicks in it then that is a dead give away. Keep driving it like this and you WILL blow damage your engine.

If you have been running it for a while and have never had these issues I would agree with Jay that is could be mechanical or bad gas. The way I ruled out both of those was to put a mix of 93/110 oct fuel in to get an effective octane rating of 104. When I did that the sounds went away which immediately affirmed my assumptions of detonation. If you have access to UNLEADED 100 octane fuel then put a tank of that in and see if it stops. To fix mine I had to have BTR pull a degree or two of timing from the top end.
 

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Jay,

Not to hijack the tread but these tunes. On a stock car, I've always heard the ecm "learns"the drivers habits and adjusts fuel curves and whatever else. Are you able to turn this "learning" function off with your tunes? I've always wondered this.
 

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Discussion Starter #14
Check the spark plugs and make sure they are in good shape. If you've been running with the tune for over 2 years without getting these issues, you'd need to start looking at some mechanical causes. Yet didn't you have similar problem about few months ago with some bad batch of gas?
I would never push the car with those sounds in the first place. You are damaging it.
Jay you are absolutely right, this is the same issue that has been happening since the supposedly bad gas incident, it hasn't stopped since. I have recycled the gas maybe 50 times since the issue started happening. I only put 93 Octane, I think it may be the timing like RedGen is pointing out? Can you look at this for me? Or is this something I can look at without having to bring my car? If I have to bring my car to SFR I can so you can look at it and maybe help me fix it? I did find vacuum leaks which I fixed, but my car still doesn't run right.

That is detonation... I had it happen to me with a BTR stage 2 tune... Pull your spark plugs and look at the ground electrode. If you see little nicks in it then that is a dead give away. Keep driving it like this and you WILL blow damage your engine.

If you have been running it for a while and have never had these issues I would agree with Jay that is could be mechanical or bad gas. The way I ruled out both of those was to put a mix of 93/110 oct fuel in to get an effective octane rating of 104. When I did that the sounds went away which immediately affirmed my assumptions of detonation. If you have access to UNLEADED 100 octane fuel then put a tank of that in and see if it stops. To fix mine I had to have BTR pull a degree or two of timing from the top end.
Maybe my timing is still off somehow? I don't believe its the tune but I would like to check my timing, I'm just not sure I can do that myself. I guess I will have to take the car back to Jay to do that?

Swap ecm and 95% sure your problem will be gone.
I have swapped the ECM back to stock and it still happens.
 

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Do you have the Torque app? You can see a lot of what your ECU is doing with that app. Might be a cheap way to start some troubleshooting. No guarantee you will find anything so don't hold me to anything haha

Check your plugs and post some pictures. Check for any damage to the electrode or pitting on the insulator.
 

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Jay you are absolutely right, this is the same issue that has been happening since the supposedly bad gas incident, it hasn't stopped since. I have recycled the gas maybe 50 times since the issue started happening. I only put 93 Octane, I think it may be the timing like RedGen is pointing out? Can you look at this for me? Or is this something I can look at without having to bring my car? If I have to bring my car to SFR I can so you can look at it and maybe help me fix it? I did find vacuum leaks which I fixed, but my car still doesn't run right.



Maybe my timing is still off somehow? I don't believe its the tune but I would like to check my timing, I'm just not sure I can do that myself. I guess I will have to take the car back to Jay to do that?



I have swapped the ECM back to stock and it still happens.
If it happens with stock timing and boost (yet the spark plugs are in good shape and installed correctly) I'd first go about doing some compression test (Especially all the detonations it's been having) then move forward. If compression tests are good start looking into checking the injectors/coils (should have been triggering CEL though) and go from there..
 

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Looking at the video, your afr gauge on the left is reading low 11s when you're on it. That says fuel is getting to the cylinders, so it may not be an issue with anything involving delivery unless it's only to one cylinder. Compression test is a good idea to help verify oil isn't getting in there enough to pre-ignite the fuel.. Otherwise if the plugs are fine, it may be the tune.
 

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Looking at the video, your afr gauge on the left is reading low 11s when you're on it. That says fuel is getting to the cylinders, so it may not be an issue with anything involving delivery unless it's only to one cylinder. Compression test is a good idea to help verify oil isn't getting in there enough to pre-ignite the fuel.. Otherwise if the plugs are fine, it may be the tune.
Maybe the intake is all slugged up and it's sucking in oil?
 
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