Been Chasing a Fueling Issue or so it seems...

B7 A4
#1

Recently i have been chasing a Fuel Pressure code that has left me stumped. This is what i have showing up:

2 Faults Found:
012555 - Low Pressure Fuel regulation
P310B - 008 - Fuel Pressure Outside Specification - Intermittent
000808 - Knock Sensor 1 (G61)
P0328 - 001 - Signal too High - Intermittent

I am guessing that the Knock Sensor code is being caused by the P310B code. When i searched the code through the Ross-Tech Wiki this is what i came up with:

[i]Possible Causes
Faulty Fuel Pressure Sensor (G410)
Wiring Harness for Fuel Pressure Sensor (G410)
Possible Solutions
Replace Fuel Pressure Sensor (G410)
Repair Damaged Wiring

 When found in Audi 2.0T "FSI" Direct Injection engines, may also have DTCs P129F/004767, P2293 and/or P0087. See TSB 24-08-58 (TPI 2017356/2) for more information on testing and updated part numbers. 

When found on Direct Injection engines, such as the 2.0T, in combination with system too lean or similar faults indicating a vacuum leak address the cause of those first. Common fault codes are found here
When this fault is stored after all of the typical failure items have been replaced or tested, verify the electric fuel pump and/or FPCM (Fuel Pump Control Module) is operating properly. Low fuel pressure or volume may be the end result of a fuel supply problem including an incorrect fuel filter when the pressure regulator is integral. [/i]

Based on that information I have checked the entire wiring harness for damage. I have checked every single hose for cracks and or a vacuum leak. Checked that the correct Fuel Filter was installed properly and also checked to make sure there was nothing clogging the fuel pickup in the tank. I have tested to ensure the HPFP was working correctly as well.

Digging further into this the Fuel Pressure Sensor (G410) comes back to the electrical sensor on the HPFP. I have verified that the sensor has connectivity and also seems to be functioning properly.

Needless to say I’m pretty stumped at whats going on. The cars ONLY mod is a APR Tune. Ihavent noticed any performance loss and the CEL is NOT on. Looking forward to getting some answers.

#2

Hey man,

I am sorry to see you are having some issues with your 2.0T. Have you tried replacing the simple things like the Fuel Rail Valve? If not, you can find it on our website linked below.

http://jhmotorsports.com/shop/catalog/valve-fuel-pressure-regulator-or-rail-valve-for-b7-a4-20t-p-1593.html

I will also send you a PM of some logs to get me since I see you have VagCom.

Jake

#3

I replaced the valve on Friday and drove all weekend the code came back. I should have logs for you by this afternoon. Thanks Jake!

#4

Logs sent to your Jake@jhm account.

#5

Thanks I will have those logs looked over and let you know if we see anything out of whack.

#6

So I never got around to updating this thread with the resolution.

After working with Jake and Dru at JHM we were able to very quickly figure out that the in tank LPFP was failing. We went through and did a couple of logs on the pump and determined that it was dropping far below spec. A good in tank pump should never go below 4 bar but mine was dropping to 1.17 bar at 4200 rpms. You could also see on the logs that the FRP was needed to ADD a ton of fuel to try to compensate for the lack of pressure from the pump.

So what i did to fix this was install a new in tank pump and a new fuel filter and reset codes. The codes have not come back and my pump is now not dropping below 4 Bar. BIG thanks to the guys at JHM for the help with the car and having the best price on the items needed to fix the issue.

Fuel Pump: http://jhmotorsports.com/shop/catalog/fuel-pump-assembly-sending-unit-oem-for-b7-a4-all-b7-rs4-p-1782.html?cPath=21_62_65_255

Fuel Filter: http://jhmotorsports.com/shop/catalog/fuel-filter-mann-oem-supplier-for-b7-a4-rs4-c6-a6-32l-p-521.html?cPath=21_62_65_255

#7

Have you double checked the part number of your low side fuel pressure sensor against the updated part number? That sensor fails regularly on a bunch of different Audis. There was a TSB about these sensors and it shows how to manually test the fuel pressure to see if the sensor was bad.

http://jhmotorsports.com/shop/catalog/fuel-pressure-sensor-low-pressure-sensor-oem-for-b7-a4-20t-p-2278.html?cPath=21_62_65_255

That sensor confused a bunch of techs when a lot of cam followers were also failing around the same time because similar codes would come up. They would throw a low side fuel pressure sensor at the problem when it was the cam follower that actually failed.

#8

So I never got around to updating this thread with the resolution.

After working with Jake and Dru at JHM we were able to very quickly figure out that the in tank LPFP was failing. We went through and did a couple of logs on the pump and determined that it was dropping far below spec. A good in tank pump should never go below 4 bar but mine was dropping to 1.17 bar at 4200 rpms. You could also see on the logs that the FRP was needed to ADD a ton of fuel to try to compensate for the lack of pressure from the pump.

So what i did to fix this was install a new in tank pump and a new fuel filter and reset codes. The codes have not come back and my pump is now not dropping below 4 Bar. BIG thanks to the guys at JHM for the help with the car and having the best price on the items needed to fix the issue.

Fuel Pump: http://jhmotorsports.com/shop/catalog/fuel-pump-assembly-sending-unit-oem-for-b7-a4-all-b7-rs4-p-1782.html?cPath=21_62_65_255

Fuel Filter: http://jhmotorsports.com/shop/catalog/fuel-filter-mann-oem-supplier-for-b7-a4-rs4-c6-a6-32l-p-521.html?cPath=21_62_65_255

#9

JimmyBones good addition to the thread I forgot that I had changed that as well.

#10

Have you double checked the part number of your low side fuel pressure sensor against the updated part number? That sensor fails regularly on a bunch of different Audis. There was a TSB about these sensors and it shows how to manually test the fuel pressure to see if the sensor was bad.

http://jhmotorsports.com/shop/catalog/fuel-pressure-sensor-low-pressure-sensor-oem-for-b7-a4-20t-p-2278.html?cPath=21_62_65_255

That sensor confused a bunch of techs when a lot of cam followers were also failing around the same time because similar codes would come up. They would throw a low side fuel pressure sensor at the problem when it was the cam follower that actually failed.

#11

JimmyBones good addition to the thread I forgot that I had changed that as well.

#12

This is good information! I would add this to your Information Thread!

#13

There was a new member that just recently posted and he mentioned he had a fueling issue preventing him from getting tuned. Perhaps it’s a good idea to point out all the fueling issues the 2.0t can experience.

#14

There isn’t enough paper in the world to write down all of the 2.0t’s fueling issues. So instead lets just say the 2.0t has ALL the fueling issues.

#15

Interesting good to know.

#16

That member if I’m not mistaken had the same issue as I did with the in tank lpfp failing? Like I said I worked with Jake and Dru to get it figured out. Other than the in tank pump going bad and the potential failure of the fpr in the filter there isn’t really any other issues that I have run into fueling wise.

#17

This is good information! I would add this to your Information Thread!

#18

There was a new member that just recently posted and he mentioned he had a fueling issue preventing him from getting tuned. Perhaps it’s a good idea to point out all the fueling issues the 2.0t can experience.

#19

There isn’t enough paper in the world to write down all of the 2.0t’s fueling issues. So instead lets just say the 2.0t has ALL the fueling issues.

#20

Interesting good to know.