Fuel cut issues

[DrZEUS]

I am running JHM tune with RAI HFC/DP on a stock HPFP. I am having some serious fuel cuts, to the point the car is not driveable.


I used to run an upgraded HPUPGRADE HPFP with APR Stage 2+ tune, switched to JHM tune but retained the upgraded pump....until a hole was punched in my cam follower which in turn damaged the piston on the pump. That is when the stock pump went back in (with a new cam follower of course).

Since that time, I noticed a "blip" here and there while driving which I later equated to a minor fuel cut. I did notice some scoring on my cam shaft from when the follower failed and was replaced, so that may be my problem afterall (a damaged cam shaft), however my mechanic seems to think it shouldn't cause fuel cuts and instead perhaps eat through followers a little quicker. I have been keeping on a eye on my follower ever since and it is fine for now.

The fuel cuts (blips) became more frequent until one day all of a sudden the car was bogging, jerking, and RPM's dancing, and even stalling once. Fuel cuts were very pronounced and noticeable at that point. I thought maybe my follower failed again so I checked it out and it was fine. After putting the fuel pump back on, the car seemed to be back to normal for another couple of weeks and then it happened again, even more pronounced this time.

Out came my trusty VAG-COM and I have these codes:

5 Faults Found:

000320 - Oxygen (Lambda) Sensor B1 S2
P0140 - 004 - No Activity - MIL ON
Freeze Frame:
Fault Status: 11100100
Fault Priority: 2
Fault Frequency: 21
Reset counter: 255
Mileage: 167521 km
Time Indication: 0

Freeze Frame:
RPM: 812 /min
Load: 17.6 %
Speed: 0.0 km/h
Temperature: 93.0°C
Temperature: 41.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 13.462 V

008342 - Post-Catalyst Oxygen (Lambda) Sensor Correction; Bank 1
P2096 - 002 - Too Lean - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 2
Fault Frequency: 2
Reset counter: 255
Mileage: 167561 km
Time Indication: 0

Freeze Frame:
RPM: 3028 /min
Load: 12.9 %
Speed: 44.0 km/h
Temperature: 92.0°C
Temperature: 33.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 13.462 V

000135 - Fuel Rail/System Pressure
P0087 - 002 - Too Low - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10100010
Fault Priority: 2
Fault Frequency: 12
Reset counter: 255
Mileage: 167590 km
Time Indication: 0

Freeze Frame:
RPM: 3646 /min
Load: 57.6 %
Speed: 136.0 km/h
Temperature: 92.0°C
Temperature: 27.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.843 V

004243 - Bank 1; Fuel Measuring System 2
P1093 - 008 - Malfunction - Intermittent
Freeze Frame:
Fault Status: 00101000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 168457 km
Time Indication: 0

Freeze Frame:
RPM: 2621 /min
Load: 12.9 %
Speed: 57.0 km/h
Temperature: 92.0°C
Temperature: 30.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.843 V

004372 - Oxygen (Lambda) Sensor; B1 S2
P1114 - 008 - Internal Resistance too High
Freeze Frame:
Fault Status: 01101000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 168468 km
Time Indication: 0

Freeze Frame:
RPM: 2384 /min
Load: 7.1 %
Speed: 69.0 km/h
Temperature: 92.0°C
Temperature: 30.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.843 V

My guess with the O2 sensor codes is when fuel cuts were taking place, the sensor was registering a lean situation. Then you can see the two codes referring to Fuel Rail/System Pressure and Fuel Measuring System 2 failing or intermittent. I cleared the codes, drove around a bit, and only got the 004243 - Bank 1; Fuel Measuring System 2 code again.

In perusing the VAG-COM website, I came across this for the Fuel Measuring code:

******************************************
17501/P1093/004243 - Bank 1; Fuel Measuring System 2: Malfunction

Possible Symptoms
- Power Loss
- Misfire(s)
- Stalling

Possible Causes
- Fuel Pressure insufficient/exceed/fluctuating
- Fuel Pump (High Pressure System) faulty
- Fuel Pressure Regulator Valve (N276) faulty

Possible Solutions
- Check Fuel Pressure (on FSI engines High and Low Fuel Pressure System)
- Check Fuel Pump (High Pressure System)
- Check Fuel Pressure Regulator Valve (N276)
- Check Fuel Filter and Filter in Fuel Pump Casing
- Special Notes

When found in 2.0l TFSI:
- Check Fuel Pressure
- Check TSB/TPI 2008753 (Rest of World), incompatibility between Fuel Pressure Regulator Valve (N276) and ECU software.

When found in conjunction with Misfires and Lean fault codes, check RVUTB: 01-09-03 or 2018919 (NAR only) 2.0T (BPY), for updated Crankcase Breather Valve
If the breather valve is faulty, full engine vacuum is typically found when removing the oil cap at idle.
******************************************

Ran a test on the N276 and it appears to be working (hear clicking during the test). Same thing with the HPFP...clicking during test. Fuel pump/filter would be the next thing to check on that list but I was wondering if anyone has any other insight on this.

[Denio24]

Just a little note, since you think your hpfp system is messed up, specifically the camshaft, check the duty cycle on the lpfp. On the other hand i noticed one time i had experienced fuel cuts, and replaced the cam follower. It looked abnormally worn for some reason. After replacing no more issues.


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[Theiceman]

What if your lpfp is unable to feed?

i agree with your mechanic its not the cam. as a test could you not put your modified hpfp.back in And drive it to see if it reoccurs ? ( i totally get its damaged and could quickly eat through a follower.)
if it happens again quickly you will know to eliminate the hpfp. then take it back out

[DrZEUS]

Just a little note, since you think your hpfp system is messed up, specifically the camshaft, check the duty cycle on the lpfp. On the other hand i noticed one time i had experienced fuel cuts, and replaced the cam follower. It looked abnormally worn for some reason. After replacing no more issues.


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The cam follower is in pristine shape. How do I check the duty cycle on the lpfp?

[DrZEUS]

What if your lpfp is unable to feed?

i agree with your mechanic its not the cam. as a test could you not put your modified hpfp.back in And drive it to see if it reoccurs ? ( i totally get its damaged and could quickly eat through a follower.)
if it happens again quickly you will know to eliminate the hpfp. then take it back out

The upgraded hpfp is missing the retaining clip on the end of the piston. I suppose I could try it for a short period and see what happens. I was looking around for a spare stock pump to test out but nobody around me has one. I may give this a shot.

Now if I can only get the bottom hose off the pump...that's caked on!

[Denio24]

The cam follower is in pristine shape. How do I check the duty cycle on the lpfp?

http://www.audizine.com/forum/showthread.php?t=368483

http://www.seatcupra.net/forums/showthread.php?t=291097

I think that for block 106 if the duty % at idle is > 60% your pump may be on the way out.

Also, this. http://www.audizine.com/forum/showthread.php?t=503346
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[Theiceman]

i have a worn one due to same issue as yours (follower) but not falling apart yet.
there are pics in a thread i created . if you want to borrow it let me know you are only half an hour from me

[DrZEUS]

Duty cycle on the lpfp checks out. Hovers in the and around the 51-54% range.

Anyone local to the Toronto/Mississauga area have a spare hpfp I can borrow for testing?

[DrZEUS]

...is there a definitive way to test the hpfp using VCDS?

[p0isin]

Other than recording requested vs actual pressure, I don't think so.

[DrZEUS]

Update: So I replaced my fuel filter since it's easy to do and fairly inexpensive. Didn't solve my issue.

Before I replace my HPFP, I thought about it some more and was hoping to get clarification. When the fuel cuts out, the car vigorously pulls back. The RPM's drop in sync with what I perceive to be a fuel cut. It's almost like the engine temporarily shuts down causing the RPM's to literally pull back. Is this actually a fuel cut or could I have an engine or even transmission problem?

[DrZEUS]

Update: So I went ahead and replaced the HPFP. Went for a spin and at first everything seemed to be back to normal. The feeling of euphoria was erased when fuel cuts happened again but this time very noticeably less in frequency and in severity.

I have felt all along my camshaft is the culprit but I keep hoping it's not the case.

Here is a fuel log (requested vs actual) I took today doing a third gear pull to almost redline. You can see the huge dip between 2500 and 5000 RPM.

2016-07-05 - Block 230 - Third Gear Pull.jpg

[DrZEUS]

Just to add, so far my fault codes related to Fuel Rail/System Pressure are gone and have not come back after a day of driving. Only codes showing up still are O2 sensor related. I wonder if the post cat sensor is the culprit. I already replaced it a year ago though....although it was an OE replacement and I had to modify the harness (one pin was missing). Are these O2 sensors typically finicky?

2 Faults Found:

000320 - Oxygen (Lambda) Sensor B1 S2
P0140 - 004 - No Activity
Freeze Frame:
Fault Status: 01100100
Fault Priority: 2
Fault Frequency: 2
Reset counter: 255
Mileage: 168504 km
Time Indication: 0

Freeze Frame:
RPM: 743 /min
Load: 16.1 %
Speed: 0.0 km/h
Temperature: 95.0°C
Temperature: 48.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.208 V

004372 - Oxygen (Lambda) Sensor; B1 S2
P1114 - 008 - Internal Resistance too High
Freeze Frame:
Fault Status: 01101000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 168506 km
Time Indication: 0

Freeze Frame:
RPM: 744 /min
Load: 17.2 %
Speed: 0.0 km/h
Temperature: 94.0°C
Temperature: 53.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.462 V

[DrZEUS]

LOL @ talking to myself.

Fuel Rail/System Pressure codes reappeared. FML.

[Denio24]

LOL @ talking to myself.

Fuel Rail/System Pressure codes reappeared. FML.

Any new fuel pressure codes besides P0087 & P1093?

[p0isin]

My only suggestion would be to log both lpfp pressure and lpfp duty cycle to see if that's causing fuel starvation if you haven't done that yet

[Denio24]

^^^ You can see that the fuel rail pressure in one of the logs dips down to 40 psi... something has to be causing that. If your lpfp system is not up to par that could definitely cause your hpfp system to put out lower pressures than normal.

Log block 231 which shows low pressure fuel system pressure (in bar) vs. RPM (3rd gear pull to redline). Post back with info.

[DrZEUS]

Update: Been really busy lately but was able to replace the engine speed sensor (G28) and it solved the severe fuel cuts, however, fuel cuts still persist and exist as "blips" or "slips" if you will under WOT mainly. The issue with the faulty speed sensor was that when the switch would malfunction, the RPM's would quickly drop which caused a severe jerking or bucking of the car which actually throws you forward. That was my main driveability issue.

The fuel cuts that now appear as blips as mentioned above, I suspect may still be due to a worn camshaft lobe. I also experience slight surging at WOT. I will post some more logs this week. Denio, at quick glance, block 231 appears to be normal but I'll run again and post back.

Thanks for the suggestions so far!