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Thread: 2016 VW GTI 2.0L Tuning, Looking for information

  1. #1
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    2016 VW GTI 2.0L Tuning, Looking for information

    Hello, I personally own a 2016 VW GTI, it is completely stock (no upgrades) with 118,xxx miles. The engine lost compression on cylinder #4, so I decided to tear the engine down and repair versus finding a used engine to put into it. I found #4 piston ring land was broke. The cylinder wall needed honing, so I decided to go with the 83mm oversized piston offered by JE pistons. Engine is all back together and running in the car. Other than the oversized piston, no other parts were upgraded other than replacing all the seals, gaskets and bolts on the engine during reassembly.

    Now the issue: The car at idle is running extremely rich, the fuel trims are trying to correct it but will eventually will go into OL Fault (system running rich code). I do not have a log on me at the moment, but I can upload a log tomorrow.

    I personally have never tuned one of these cars and honestly don't even work on them often. But my question is, do any of you believe that going with just an oversized piston (stock compression ratio of 9.6:1) should have caused the stock tune to not be enough for this car to run without issues? (from 1984.3cc to 2008.42cc)

    So I am looking into purchasing the credits to license the car, I performed a read of the file. And was given the Stock file from HP Tuners server. I looked it over, and honestly was lost on even where to start with trying to do fueling adjustments. So if anyone have any links or information on these cars MAF/VE calibrations and the correct way to adjust the fueling, I would greatly appreciate it.

    Thank you,
    Mark

  2. #2
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    Attached is the file that I received from HP Tuners server as the stock file, and also a log of the car.

    You will see at the beginning of the log the short term fuel trims are able to keep the cars commanded lambda and actual lambda on target. But if you go to the very end of the log, you will see the fuel trims will sky rocket on the negative side trying to remove fuel and can not keep the actual lambda on target with the commanded.

    Is there by chance that I am having an mechanical issue (fuel injector sticking open once up to temperature?) or could this be something within the calibration?

    Any help will be greatly appreciated. Again, I am not very knowledgeable on these cars.
    Attached Files Attached Files

  3. #3
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    I doubt an overbore would cause this issue, I do believe you are correct in your guess of a stuck injector, checking plugs should give you an idea of the cylinder/s that may have the issue

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    Tyler,

    Thank you for the input. I did today just pull the plugs and found one plug completely black from fuel. So I pulled the injectors and handed them to my local injector guy to test the injectors to see if that one specifically is leaking/stuck open. Hopefully they are able to find something with the injector that has the fouled plug.

    I will post back here once I find more out on this.

  5. #5
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    Quote Originally Posted by Mark@TuckerPerformance View Post
    Tyler,

    Thank you for the input. I did today just pull the plugs and found one plug completely black from fuel. So I pulled the injectors and handed them to my local injector guy to test the injectors to see if that one specifically is leaking/stuck open. Hopefully they are able to find something with the injector that has the fouled plug.

    I will post back here once I find more out on this.
    Don’t even bother lol, just get a new set of MK7 R injectors as they are a common failure point

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    Just a update, I was going to take them to my local injector guy to check the injectors but he would not have been able to check them out until Friday. So I did some troubleshooting by moving parts around.
    I moved the very black spark plug which was at cyl # 4 to cyl # 1.
    I moved the coil that was at # 4 to # 3.
    I moved the injector that was at # 4 to # 2.

    Cold start up the car runs perfectly normal, then once the car gets up to full operating temperature. It will start making its way to a very large negative fuel trim to the point where the long term fuel trim will hit -100% and then the car will still be running .65 - .75 lambda at idle.
    All of this while HP Tuners in logging, and the misfire count will start counting on # 4 still. And sure enough # 4 spark plug is very black like the original one that is now in # 1 (which is now cleaned right up).

    I checked compression across all of the cylinders. They all are right around 175-180psi. I checked that I am for sure getting spark from # 4 coil (using multiple coils and using a inline spark tester).

    The next step I am about to do when the car cools off again, is check the entire wiring of # 4 fuel injector. *adding this after posting* I am going to check to see if # 4 intake runner flap is possibly closing to far????
    But other than that, I am lost right now.

    Do you have any other suggestions or things that I should be checking?

    Thank you,
    Mark
    Last edited by MarkTucker; 08-25-2021 at 03:18 PM.

  7. #7
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    Quote Originally Posted by TylerJDubbs View Post
    Don’t even bother lol, just get a new set of MK7 R injectors as they are a common failure point
    Tyler,

    Are the MK7 R injectors the same flow rate as the MK7 GTI?

  8. #8
    Quote Originally Posted by Mark@TuckerPerformance View Post
    Tyler,

    Are the MK7 R injectors the same flow rate as the MK7 GTI?
    NO

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    Alright guys, looking for help still.
    I have attached the stock file which is what is currently in the vehicle and also a log of the car from cold start with almost a 30min drive to show as much data as possible.
    The car is still running extremely rich which ends up fouling the spark plug on #4 cylinder and causes the misfire that you will see at the end of the test drive log. Seems that it gets worse as the car warms up.
    I did end up putting (4) brand new VW fuel injectors in it. (used the factory replacement injectors for this car, not the R injectors)
    It had (4) new NGK OE spark plugs in it. (now has one fouled again)

    This motor had a broken ring land on # 4 piston with extremely low compression, so I rebuilt the motor with 83mm (+.5mm oversize) JE Piston. So I am betting that whatever is causing this might have caused the stock piston to fail (maybe, I don't know just thinking that might have been the case).

    I have spark the whole time, even while misfiring it does still have spark (testing using a inline spark tester).
    It has good compression of 175-180 across all cylinder.
    I checked to see the intake manifold flap on #4 had some issue where it was blocking the runner on just #4 but seem to be completely fine and only moved when the rest moved.

    I moved around the camshaft adjuster solenoids to see if those could have been causing the issue. (moved them from #4 cylinder to #1 and #2 cylinders location)
    Moved the ignition coils around, moved the spark plugs around while adding a new plug when the #4 cyl would foul the plug in its spot.

    What else do I look at?
    Attached is a screenshot of the codes I got at the end of the test drive.
    Codes after 1 trip.png

    If anyone has any ideas, suggestions, things to check. Please let me know. I am completely lost.

    Thank you,
    Mark
    Attached Files Attached Files

  10. #10
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    Quote Originally Posted by Mark@TuckerPerformance View Post
    Alright guys, looking for help still.
    I have attached the stock file which is what is currently in the vehicle and also a log of the car from cold start with almost a 30min drive to show as much data as possible.
    The car is still running extremely rich which ends up fouling the spark plug on #4 cylinder and causes the misfire that you will see at the end of the test drive log. Seems that it gets worse as the car warms up.
    I did end up putting (4) brand new VW fuel injectors in it. (used the factory replacement injectors for this car, not the R injectors)
    It had (4) new NGK OE spark plugs in it. (now has one fouled again)

    This motor had a broken ring land on # 4 piston with extremely low compression, so I rebuilt the motor with 83mm (+.5mm oversize) JE Piston. So I am betting that whatever is causing this might have caused the stock piston to fail (maybe, I don't know just thinking that might have been the case).

    I have spark the whole time, even while misfiring it does still have spark (testing using a inline spark tester).
    It has good compression of 175-180 across all cylinder.
    I checked to see the intake manifold flap on #4 had some issue where it was blocking the runner on just #4 but seem to be completely fine and only moved when the rest moved.

    I moved around the camshaft adjuster solenoids to see if those could have been causing the issue. (moved them from #4 cylinder to #1 and #2 cylinders location)
    Moved the ignition coils around, moved the spark plugs around while adding a new plug when the #4 cyl would foul the plug in its spot.

    What else do I look at?
    Attached is a screenshot of the codes I got at the end of the test drive.
    Codes after 1 trip.png

    If anyone has any ideas, suggestions, things to check. Please let me know. I am completely lost.

    Thank you,
    Mark
    couple things i noticed.....

    LPFP is cranked on 11bar actual, post cat sensor reading lean, pre cat sensor reading rich.... some places to start...

  11. #11
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    Just wanted to close out this post with the fix for the issues that I was experiencing. To hopefully help anyone that comes across this same issue.

    Issue: an extremely rich condition (mainly idle) which caused to foul the spark plugs, then misfire.
    Fix: new HPFP (high pressure fuel pump)

  12. #12
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    Quote Originally Posted by TylerJDubbs View Post
    couple things i noticed.....

    LPFP is cranked on 11bar actual, post cat sensor reading lean, pre cat sensor reading rich.... some places to start...
    So A note for this thread incase someone else runs through this... Ive now looked at a few logs across this forum and my personal S3 and the LPFP is always showing 11Bar... Until someone can show me a log of it not at 11bar... im thinking its a logger issue of some sort? but VCDS shows the same.. - But end result for this person was the HPFP.
    2005 Cummins 325/600 G56 3.73
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