P0087 Low Pressure, temperature related

Red64

Member
Joined
Feb 8, 2013
Location
Wisconsin
TDI
2005 New Beetle, 2014 Sportwagen
2014 Sportwagen with 44,000. 3rd owner this was a buy back car so detailed service history not know.

Car starts and runs fine for 15 to 20 mins, or until it gets hot. Once at temp, and I push it over 2000 rpm get the flashing glow plug lamp and a P0087 fault. Let the car cool down and it runs fine again until it gets hot. Changed the filter, it was original, and pulled the modulator NO metal gunk in the hole or on the screen. VCDS, yes I bought it from Ross Tech, tells me that the requested pressure was around 1500 bar and the actual was around 1000 bar, given the document i just read this would be within the quoted 230 to 1800 bar of the pump.

I Electrical Engineer in me says its probably a heat soaked pressure switch, but it could be the regulator. Any thoughts or comments?

One last question, where is the pressure measurement port, i understand 1800 bar is not to be mess with, but to verify the pressure readings you need to install a gauge. There looks to be a plug under the output line from the HPFP. Is this the gauge port?

000135 - Fuel Rail/System Pressure
P0087 - 001 - Too Low - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 71244 km
Time Indication: 0
Date: 2058.14.14
Time: 18:51:23

Freeze Frame:
RPM: 1955 /min
Inj. Quantity: 39.0 mg/str
(no units): 5.0
Pressure: 1592.0 bar
Pressure: 1096.0 bar
Temperature: 43.2°C
Tank Cont.: 37.5 l

This was the first P0087 fault they are all in the same Ball Park.
 
Last edited:

Red64

Member
Joined
Feb 8, 2013
Location
Wisconsin
TDI
2005 New Beetle, 2014 Sportwagen
Could this be an injector sticking open when hot? Just checked my oil level and its off the top of the stick, normally in the crosshatch. Oil is black, not creamy white, fuel leaking out of a stuck injector would pool on the piston then run into the sump. I am guessing the cat would mask the smoke when the car was started.
 

MikeH31324

Veteran Member
Joined
Aug 5, 2019
Location
SE Georgia USA
TDI
2012 Golf TDI 2 door 6MT
Yes a malfunctioning or sticking injector could cause you’re issues. Normally injector issues in common rail engines seem to present themselves in the 250000-30000 mile range. I would think it is very uncommon to have an injector fail at 44000 miles, but that would be the only reasonable explanation for the oil dilution.
 

Red64

Member
Joined
Feb 8, 2013
Location
Wisconsin
TDI
2005 New Beetle, 2014 Sportwagen

I replaced the pressure switch on the passenger side of the fuel rail because I got an intermittent fault for the switch, but it made no difference. From cold it takes about 10 mins before the low pressure fault occurs. I logged the above as it occurred. Requested pressure in blue, actual in red, injector duration in green. For reference the horizontal lines on the upper graph are 2000bar 1500bar 1000bar 500bar and zero. The injector quantity ranges from 0.3 mg/str to -0.3 mg/str on the lower one, the plotted points are all from the same log. My next thought was to replace the pressure regulator, but the injector duration puzzles me. Anyone got any insight.
 

Red64

Member
Joined
Feb 8, 2013
Location
Wisconsin
TDI
2005 New Beetle, 2014 Sportwagen
Up date, still no fix. Remove the injectors and had them cleaned and tested. Everything was as it should be. Reinstalled the injectors and a new pressure regulator on the fuel rail. Ran the car and got the same low fuel pressure warning when warm. ordered a HPFP mounted modulator from Europe and installed that this week. Tested and got the same fault, granted it took longer but it's getting cold in Wisconsin.

Next are the fuel pumps. I have the in-tank pump and the lift pump or Aux pump, but need to buy the HPFP. Any recommendations on HPFP sources?

Is there a way to test the pumps while they are on the car? I am thinking VCDS and some careful re-plumbing.

Any input would be appreciated.
 

Red64

Member
Joined
Feb 8, 2013
Location
Wisconsin
TDI
2005 New Beetle, 2014 Sportwagen
Not the pump in tank, changed that . I half thought it probably was, as there was no filter on the bottom of the pump assembly and the pump was hot. Ran the hose over the aux lift pump until it was good and cold and the problem persisted.

Unless someone has other ideas my best guess would be that when cold the HPFP seals enough to pump the required pressure, as the pump gets hot the pistons start to leak and the pressure is lost. Given that the heat mass of the pump is large it takes a long time to cool, but once cold the pump will work fine until hot. looks like i get to change an HPFP.

Still looking for purchase options.
 

Red64

Member
Joined
Feb 8, 2013
Location
Wisconsin
TDI
2005 New Beetle, 2014 Sportwagen
So to update. I fitted the new HPFP at the weekend and it seems to have fixed the problem. Requested fuel pressure matches the actual, and no lost after the fuel gets hot. I got the VW rebuilt pump from ID parts

A couple of comments that may help others:
I never saw metal particles in any of the places listed to check.
I had near perfect fuel pressure for the first 10 min until the fuel was warm.
Looking at the log, the pressure drop off was very abrupt.
Changing the HPFP is not that hard, only a little worse than changing the timing belt.
You don't have to remove the timing belt and therefore the engine mount, you can loosen the tensioner, and work around the belt. If you are close to your timing belt change do both, at 44,000 I was not.
Prime, prime, prime. I was amazed at the amount of air i got out, or heard cycling through with both the lift and aux pumps running.

Hope this help someone.
 
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