Dreaded P310B "Low Fuel Pressure Regulation - Fuel Pressure out of Spec"

[LittleDozer]

Update: P310B is now a very well known code for when these cars need a new low pressure fuel pump. You can get a "flex fuel" version for the same price as the normal OEM pump.

[GRUMPY-S4]

Im having an issue on the HPFP side

[LittleDozer]

Is it going limp? Symptoms?

[jran76]

What fuel are you running? Do you have logs with specified and actual fuel pressure?

[LittleDozer]

Running BP 93. I have no idea what the previous guy ran. Bought the car with 19k miles. Yes the actual is VERY often slightly below the specified. It often is lower than specified stock too without throwing any codes. I can provide logs if you'd like to see them?

Thanks

[fitzydude]

Its interesting you're only seeing the problem in sport mode. Its likely due to the more aggressive throttle responsive, looks like the pump can't keep up with the rapid throttle opening in sport mode. Sounds like you need a new pump, or maybe filter.

[Tony@EPL]

Im having an issue on the HPFP side

Is it going limp? Symptoms?

Unrelated. Stock fuel pump gas car vs E85 autotech pump car.

First we've seen this issue since we originally tuned the cars way back when. Obviously Im in contact with Jordan on this, but I unfortunately think its hardware related. That is our most commonly used stage 2 file.

[GRUMPY-S4]

Unrelated. Stock fuel pump gas car vs E85 autotech pump car.

First we've seen this issue since we originally tuned the cars way back when. Obviously Im in contact with Jordan on this, but I unfortunately think its hardware related. That is our most commonly used stage 2 file.

You think mine is hardware related as well Tony?

Hopefully the coolant issue on the supercharger was causing it. I will be getting car back today with coolant issue resolved.

[bhvrdr]

Its interesting you're only seeing the problem in sport mode. Its likely due to the more aggressive throttle responsive, looks like the pump can't keep up with the rapid throttle opening in sport mode. Sounds like you need a new pump, or maybe filter.

my though too. hpfp or rail related (high pressure relief valve?). i assume you're not running e85

mike

[jran76]

Running BP 93. I have no idea what the previous guy ran. Bought the car with 19k miles. Yes the actual is VERY often slightly below the specified. It often is lower than specified stock too without throwing any codes. I can provide logs if you'd like to see them?

Thanks

Have you talked to Tony/EPL? I know on a couple of the tunes he just had to tweak the threshold for that particular error message. EDIT: Nevermind, I see you have, and Tony's response.


Grumpy's issue is a little different in that you can see a pretty big delta between actual and specified (like 10-20%).

I'll shoot you a PM with my email if you want to send the logs, or you can post them to a file sharing site.

[LittleDozer]

Yeah what seems to happen is in the high end of 3rd gear the LPFP dips down to levels at one point to 3.9 bar, usually hovering around 4.1-4.2 bar for a bit, then when it shifts into fourth gear it spikes up to 7.5-7.8 bar. It's almost like it's not quite responsive enough to keep up with demand and then locks itself up in some sort of overdrive mode in order to supply fuel.

At the same time, the fuel rail pressure goes up around 118,000hpa. I've heard that maybe this is too high, and possibly this is because the HPFP is trying to compensate for the LPFP?

[LittleDozer]

my though too. hpfp or rail related (high pressure relief valve?). i assume you're not running e85

mike

Yeah I will probably check the PRV as well, seeing that the pressure spikes up to 7.8 bar at some points in the system.

[jran76]

Yeah what seems to happen is in the high end of 3rd gear the LPFP dips down to levels at one point to 3.9 bar, usually hovering around 4.1-4.2 bar for a bit, then when it shifts into fourth gear it spikes up to 7.5-7.8 bar. It's almost like it's not quite responsive enough to keep up with demand and then locks itself up in some sort of overdrive mode in order to supply fuel.

At the same time, the fuel rail pressure goes up around 118,000hpa. I've heard that maybe this is too high, and possibly this is because the HPFP is trying to compensate for the LPFP?

When does the pressure hit 118,000 hPa? My car runs consistently at 120,000 to 135,500 hPa from 4000 rpm to redline.

[bhvrdr]

Its a good idea what jran suggests as well with contacting your tuner to help troubleshoot. APR apparently had a similar issue pop up on a few cars and was able to make a change (assuming you rule out a hardware issue)...

http://www.audizine.com/forum/showth...=1#post9730550

Mike

[LittleDozer]

When does the pressure hit 118,000 hPa? My car runs consistently at 120,000 to 135,500 hPa from 4000 rpm to redline.

PM me your email and I'll shoot over the logs

[LittleDozer]

Its a good idea what jran suggests as well with contacting your tuner to help troubleshoot. APR apparently had a similar issue pop up on a few cars and was able to make a change (assuming you rule out a hardware issue)...

http://www.audizine.com/forum/showth...=1#post9730550

Mike

Thanks for the link - checked that one out in my quest to figure out what's happening already :/

Yes I've been working with our local guy here and he's been communicating/sending logs to Tony.

[GRUMPY-S4]

For some reason I highly doubt my issue is hardware related.

[LittleDozer]

Unrelated. Stock fuel pump gas car vs E85 autotech pump car.

First we've seen this issue since we originally tuned the cars way back when. Obviously Im in contact with Jordan on this, but I unfortunately think its hardware related. That is our most commonly used stage 2 file.

Tony - what are the thresholds that could trigger limp mode? Is it because the pump is spiking up to 7.8 bar and going below 4 bar? If this is the case is there a way to modify the tune so that it thinks 3.9 and 7.8 are OK? If this makes it run fine then I'd think that would point to the LPFP being the issue.

[Tony@EPL]

Tony - what are the thresholds that could trigger limp mode? Is it because the pump is spiking up to 7.8 bar and going below 4 bar? If this is the case is there a way to modify the tune so that it thinks 3.9 and 7.8 are OK? If this makes it run fine then I'd think that would point to the LPFP being the issue.

I would have to look at the file closely to pull out these thresholds. We generally do not make one of changes to fix things like this. We used the 551F file in the E and G cars so there's at least 50 cars running this map (and most running the DSG tune as well) without the codes. I'd say given that the car less less then 20k (and a long life a head) you want to get to the root cause as opposed to bandaiding.

[LittleDozer]

I would have to look at the file closely to pull out these thresholds. We generally do not make one of changes to fix things like this. We used the 551F file in the E and G cars so there's at least 50 cars running this map (and most running the DSG tune as well) without the codes. I'd say given that the car less less then 20k (and a long life a head) you want to get to the root cause as opposed to bandaiding.

I'll let you know if Nur Technic finds anything today

[Tony@EPL]

I'll let you know if Nur Technic finds anything today

Have them call me if they need anything.

[LittleDozer]

Turns out the Audi dealer didn't replace the G410 because I didn't have a CEL. Ridiculous since the part has visual corrosion. Nur is replacing it and if it works I'll go after the dealership.

[skiptowncat]

For some reason I highly doubt my issue is hardware related.

Its not unheard of for auto-tech fuel pump internals to be bad from factory. There was a few on the mazdaspeed platform like this.

[bhvrdr]

Turns out the Audi dealer didn't replace the G410 because I didn't have a CEL. Ridiculous since the part has visual corrosion. Nur is replacing it and if it works I'll go after the dealership.

Glad you have something solid to go on now. Hope that does the trick. Nice to have your tuner working closely with you too. props to EPL. Let us know if the G410 does it. Always nice to keep track of what items are failing.

Mike

[LittleDozer]

G410 didn't work. Car is still spiking up to 7.5+ bar pressure. Spec is 3.5-7. I can literally hear the pressure building up in the LPFP area. They are going to replace the pressure control valve and the fuel filter. My PCV is doing some weird stuff like fully closing off even when pressure is 7.5 bar. More to come...


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[fesmail]

I've been having this issue for a year now on my APR stage 2..... APR requires logs from me in order to provide support......same code, no CEL, car does not go into limp mode but does cut fuel at WOT and feels like a hard misfire.......no issues when running stock tune

[LittleDozer]

Question for whoever knows: when the duty cycle for the fuel regulating valve is at 0%, does this mean the computer is telling it to stay fully open or fully closed? Also, is the fuel regulating valve the same thing as the pressure release valve connected to the fuel filter?

[quickglx]

I am also running EPL stg 2. I had the same low side fault occur once. I guessed it may have been related mixing too much e85(~40%) and dialed it back to ~30% and haven't had any issues since. Never had a lean fault though so maybe coincidental that it hasn't popped up again.

[LittleDozer]

Have them call me if they need anything.

Fuel filter (with regulator valve inside) didn't work. Nur wants to replace the HPFP, but I have seen a lot of people have pulled the LPFP first. Car has high pressure in the low pressure fuel system, and low fuel rail pressure.

Tony - do you think it's an issue with the HPFP or LPFP? Could be an issue of the LPFP malfunctioning and putting out too much fuel, or the regulator in the HPFP isn't functioning correctly?

[fesmail]

Any updates on this?

[LittleDozer]

Took a junk load of logs on the car and definitely notice some weird figures. Car is running rich WOT and we're not sure why. Could be an issue with the HPFP but haven't replaced it yet. Sent the logs over to a shop that works on high end cars and have an appt scheduled for next Wednesday to get the car looked at.

[LittleDozer]

So far with the autotech upgrade and new pump the car is running as it should. Knock on wood.


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[LittleDozer]

5 minutes later I now have the following:
First is due to DSG tune and isn't an actual issue.




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[AudBoost]

Not sure if this is helpful: http://wiki.ross-tech.com/wiki/index...2/P0068/000104

But looks like a bad manifold pressure sensor could cause the throttle position correlation fault. I would start by reseating the sensors. I am sure the shop that installed the HPFP had to disconnect the one on the passenger side to do the install.

[LittleDozer]

Not sure if this is helpful: http://wiki.ross-tech.com/wiki/index...2/P0068/000104

But looks like a bad manifold pressure sensor could cause the throttle position correlation fault. I would start by reseating the sensors. I am sure the shop that installed the HPFP had to disconnect the one on the passenger side to do the install.

Thanks. I'm going to clean the TB and make sure the AWE filter is installed right. Smoke test may be in order if that doesn't pan out.

[LittleDozer]

Does this look like it needs cleaning? Some carbon buildup back there but I wouldn't think enough to throw a code after 6 WOT pulls?


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[LittleDozer]

Update: cleaned TB and the gearbox. No codes related to TB or boost but P310B came back. Since upgrading to autotech HPFP the car doesn't go limp but it is still noticeably bogged down.


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[CrownSeven]

You sure are patient.

At this point I would've dumped that e85 file, load back on your normal epl file, install a crank pully, and call it a day.

[LittleDozer]

You sure are patient.

At this point I would've dumped that e85 file, load back on your normal epl file, install a crank pully, and call it a day.

I'm running 93 on normal EPL stage 2

[LittleDozer]

Going to keep updating this in case someone in the future has the same problem. Here is the HPFP specified versus actual. Right where the engine has trouble the HPFP pressure is very high compared to specified. Under load the LPFP dips and then decides to go into overdrive.