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Help! Fuel cut issue

choloblanco

Passed Driver's Ed
Alright, do let me tell you first what the issue is and then what I've done. While cruising around, sometimes at WOT, sometimes while taking off, a lot of time while coasting to a stop in any gear, slowing down while lightly tapping the accelerator, etc.. you get the idea. At these times, I'll feel what feels like brief fuel cut. Kind of like having an invisible person tap on the gas lightly or sometimes not so lightly. I'll feel it while accelerating sometimes too. It seems to get worse with heat outside and I have no clue what else to do.

I had this present with a P0456 code, so I thought it might be the N80 valve. Replaced that, fixed the code, problem still there. Feels marginally better, but still there.

No more codes now, great. So after more reading I think it might be the LPFP sensor on the HPFP. I replace that, marginally better, same issue though. Then I replace the LPFP controller under the back seat on the pump itself. Same deal. Then, I replace the seals on the actual LPFP; those orange ones that are seated on it. They needed replacing it seems, but still no luck. After all of that I replace the LPFP itself and while the issue has gotten "better" it's still there and I still feel the need to drive like a grandma because I hate this stupid problem and it's present on every drive.

My car is a 2013 Golf R, IE CAI, 42DD downpipe, IE stage 2 tune. Otherwise it's stock. If someone can please offer me any help on this, I'd greatly appreciate it. I want to enjoy driving again.
 
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choloblanco

Passed Driver's Ed
I managed to get a hold of a VAG-VOM cable. The codes I found are below. I am under the assumption that I need a new DV, and maybe a new fuel rail pressure sensor. But maybe a new HPFP too? What are your thoughts? The HPFP I have is an upgraded APR model that's only been on there for about a year and a half. There were also codes for intermittent misfires on all cylinders but I'm assuming that that is due to the fuel cut problem, and not something wrong with the motor. Prior to the fuel cut thing, everything ran great and I had no misfire codes.

004243 - Bank 1; Fuel Measuring System 2
P1093 - 008 - Malfunction - Intermittent
Freeze Frame:
Fault Status: 00101000
Fault Priority: 2
Fault Frequency: 6
Reset counter: 255
Mileage: 233004 km
Time Indication: 0
Date: 2015.11.27
Time: 01:22:24

Freeze Frame:
RPM: 4389 /min
Load: 3.5 %
Speed: 82.0 km/h
Temperature: 86.0°C
Temperature: 47.0°C
Absolute Pres.: 460.0 mbar
Voltage: 13.589 V

008801 - Boost Pressure Control Valve (N249)
P2261 - 008 - Mechanical Malfunction
Freeze Frame:
Fault Status: 01101000
Fault Priority: 2
Fault Frequency: 46
Reset counter: 255
Mileage: 233011 km
Time Indication: 0
Date: 2015.11.27
Time: 01:45:33

Freeze Frame:
RPM: 3612 /min
Load: 4.7 %
Speed: 91.0 km/h
Temperature: 84.0°C
Temperature: 36.0°C
Absolute Pres.: 460.0 mbar
Voltage: 13.589 V

012555 - Low Pressure Fuel regulation
P310B - 004 - Fuel Pressure Outside Specification - Intermittent
Freeze Frame:
Fault Status: 00100100
Fault Priority: 2
Fault Frequency: 5
Reset counter: 255
Mileage: 233080 km
Time Indication: 0
Date: 2015.11.27
Time: 05:07:40

Freeze Frame:
RPM: 3222 /min
Load: 23.5 %
Speed: 126.0 km/h
Temperature: 93.0°C
Temperature: 45.0°C
Absolute Pres.: 450.0 mbar
Voltage: 13.335 V
 

GTIZRX

New member
Hey, give me a call when you get a chance, and if you want bring the car by and see if I can help figure out what is going on with it.
 

Allchokedup

Autocross Champion
Just wanted to say what's up to my Texas homes!
I think I have fuel issues as well but on another platform. Good luck!
 

choloblanco

Passed Driver's Ed
After replacing the fuel filter and the diverter valve, my issue is still there. I still need to replace the fuel rail sensor, which I'll do this weekend, but if that doesn't work, then I have no clue what I need to do to fix it outside of taking it to an actual mechanic.
 

choloblanco

Passed Driver's Ed
So after swapping the sensor and clearing the codes, my problem is still there. Granted, it's the biggest improvement I've seen. Fuel cut doesn't happen as often, nor as violently, but it's definitely still present on every drive. Could this mean that my HPFP is in need of replacement? That's literally the only thing left I think it could be.
 

ROH ECHT

K04 PLAY
To me what you've said makes me think of a moment when fuel pressure is lost or released. Not sure, and would need to test it, but it could be on the low or the high side. Because the LPFP could be losing pressure through the LPFP's check valve on its outlet which would return fuel to the tank. I left out filter because you replaced it...hopefully with the correctly regulation. On the high side it could be from the FPRV (fuel-rail pressure liming valve) which is mounted on the fuel rail to release excess pressure back into the low side. You can only catch what is going on by having an active data log running for both MB 230 and 231 at the same time in VCDS__press 'stop' and end the log when you felt it and then pull up the data logged, scroll to near the end of the data, and see if you can spot pressures dropping quickly and briefly on either side....or by having a gauge spliced in and have someone watch it while you drive. With a gauge you would need to do so on both the high and then the low sides. It could also be a pause or moment when the source of power to either pump is briefly lost, but that should (pretty sure) store a fault. Oh wait, it did. So you have leads given the codes. Inspect the N276 on top of the HPFP...see if it is cracked or its wiring connection has an issue. Have the pressures thoroughly tested for both the LPFP and HPFP. Keep an eye on the work load % for the LPFP in the MB 231 data. Hopefully your volunteered help knows about all this. Confirm the replacement fuel filter regulation is correct.
 
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GTIZRX

New member
This issue is quite puzzling, when he brought the car over we went through what he had done which is stated in the first post. So we just covered the basics with known good parts from one of my R's. Coil packs-no change, DV-no change. So, I then checked the fuel filter and the rear connection was disconnected. I reconnected it and still no change. He has since replaced the fuel filter with a OE fuel filter (6.6 Bar) and replaced the sensor on the fuel rail. Still no change. I haven't talked to him since last Saturday so I don't know if he has it figured out yet. Do you think his tune is corrupted somehow?
 

GolfRfrontend

Passed Driver's Ed
I’m audi certified dealer technician.
First off get faults and buy Bentley service manual and follow trouble tree lay out and I guarantee if your somewhat knowledgeable in cars you’ll figure it out fast. Aplease stop being a mechanic and do you due diligence.

Bad part about tuning you’ll never can revert back to stock tune. Only dealer can do that.

I would advise to stop throwing and swapping part at the car, but you looks like I’m that’s to late. Not saying it related to the tune but maybe. I re-read you symptoms it definitely fuel related. Engine are tricky especially audi /vw since you already replaced majority fuel related components except for 1 HPFP.

like I stated before HPFP common audi/vw failure but fails in different ways.





#buybentlyservicemanual
 

choloblanco

Passed Driver's Ed
I took it to a shop to get it looked at, but after two weeks he finally got to look at the car, and he told me he didn't work on modded vehicles. He did unplug the MAF sensor and the hesitation issue went away. So, now I have the car back; back to square one. So if the issue disappears with the removal of the MAF sensor, would that not indicate a bad MAF? Or even a small boost leak somewhere? I did call Integrated Engineering to see what they thought and they are of the opinion that it could be a bad MAF or MAP sensor.

I can't seem to find a Bentley Service Manual for my year model.
 

choloblanco

Passed Driver's Ed
I’m audi certified dealer technician.
First off get faults and buy Bentley service manual and follow trouble tree lay out and I guarantee if your somewhat knowledgeable in cars you’ll figure it out fast. Aplease stop being a mechanic and do you due diligence.

Bad part about tuning you’ll never can revert back to stock tune. Only dealer can do that.

I would advise to stop throwing and swapping part at the car, but you looks like I’m that’s to late. Not saying it related to the tune but maybe. I re-read you symptoms it definitely fuel related. Engine are tricky especially audi /vw since you already replaced majority fuel related components except for 1 HPFP.

like I stated before HPFP common audi/vw failure but fails in different ways.





#buybentlyservicemanual
In case anyone is curious. I fixed the issue. It was my MAP sensor. Replaced it and the car is back to running beautifully.



#didntneedaservicemanual
 
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