3.0TDI (CCWA) Low Fuel Pressure DTC (P0087)

[Sootpig]

Hello everyone!

I hate for my first ever post on here to be asking for help, but im scratching my noggin so much my hairs falling out.

I recently brought a 3.0 TDI B8 Avant on 96k miles, engine code CCWA.

On the way home from buying (350 mile trip) it drove great, apart from after stopping at the services, when it stalled after re-starting the engine. I thought nothing of it, and carried on

then last week, i started the car (warm engine) and the glow plug light started flashing and the EML was on.

plugged in VCDS, and it gave me a code for low fuel pressure (P0087) First off i tried putting premium quality diesel in, just in case it was the questionable quality diesel i put in to get home. The power band improved and the engine stopped 'flat spotting' at 4,200 like it had been doing, but after the next hot start, the problem was back.

Yesterday, i replaced the fuel filter, the old one looked dirty, but not as bad as i have seen before:



Today I took the car for a drive and it's pulling nicely through the rev range and hits 5,500 rpm which it wasn't doing before (ran out of puff at about 5K). But after stopping off to take some pictures, and re-starting the car (half an hour or so), the same problem appeared, glow plug light flashing, EML on, engine stalled of first start. P0087. Cleared the code (I took my laptop with me) and drive home without any problems.

Has anyone else experienced these symptoms? the car drives well and feels as fast as the R32 I had previously (as it should) and this fault only ever appears when starting a warm engine, never when driving, or cold starting.

Any suggestions or ideas would be greatly appreciated, and I'm sorry for the long SOS post being my first one.

 

[NotNormal]

I've had issues with a similar fault code, after everything, and I did allot of things, it was the fuel pump relay
In my a6, it's located under the drivers seat (not sure for your car)

As its only a couple of quid part, I'd replace that first, then see how you fare

I know of a TPI from Audi, and you need to check for swarfe at the high pressure pump, easy enough to do, undo the balance pipe and take out the metering valve (side of the HPFP) and see if there is any swarfe.

My first port of call would be the relay though, cheap to try, clean and you don't get your finger covered in the sink of diesel


Hope it helps

Tom

 

[Sootpig]

Hmm i'll look in to the relay, although it seemed to be switching fine when I cycled the pump with VCDS after changing the filter to bleed the fuel system, so I'm not sure that would be causing my issue.

What exactly were the symptoms in your case, if you don't mind me asking?

 

[NotNormal]

My symptoms were :

Driving along, then randomly the coil light would flash and the car would go in to limp mode.
This gradually got worse and worse, firstly only happening once every two weeks, then over 15,000 mils ish, getting to the point of every few hundred metres.

We tried re-addapting so many modules, on Audi Germany's request, then I had a complete fuel system (rails, injectors, LPFP, HPFP, line, ect...., the car was fine for about 10 miles, then, limp mode.

Audi had it back, checked the wiring loom complete, nothing......

Then, they took out the relay, took the top off it, and with a magnifying glass you could see a tiny strand of wire, just looping out of the main coil of wire, as it sat it made contact, but when you knocked it (simulating bumps in the road whilst driving) the wire broke contact momentarily, thus flagging the low fuel pressure warning.

Hope this helps

Tom

 

[Sootpig]

Cheers Tom, I've spoken to a few people regarding the issue, and the general consensus is the lift pump. Not the supplementary pump, but the lift pump in the tank. I didn't even realise there was on in the tank, I thought the pump in front of the filter was the only one, but apparently not.

So tomorrow, I'm going to get to get access to the tank lift pump, and test it, if it runs, I'll check the flow rate.

Today on my way home, I was driving around in 6th and the revs dropped to near idle, when I put my foot down a little, the glow plug light started flashing, and the low fuel pressure code was generated. This is the first time it's actually happened to me while driving.

My theory is; the HPFP and one of the electric pumps is working fine (lift pump is #1 suspect) and together they can usually pull enough fuel, but when the revs dropped, the HPFP (run from the aux belt) no longer has the power to pull the fuel on it's own. Putting my foot on the accelerator increased the requested fuel pressure and the requirement wasn't met, so a fault code was generated.

That's my theory, anyway. I will endeavour to find out if one of the pumps is faulty (or indeed the relay!) and i will report back with my findings in the hope to help someone else out in future.

 

[NotNormal]

You should be able to hear the in tank pump prime when you cycle the ignition.

Good luck

 

[Sootpig]

As promised, albiet a long time coming; My solution was in the end a replacement HPFP. After replacing the rail pressure sensor and the pressure control valve with no sucsess, I checked the upstreme pressure to the pump, which held a steady 4.5BAR so i replaced the pump with a known working unit and bam, runs like a dream now. I can finally start to fall in love with this car after a year of loathing it.





Its quite an involved job, but really not as hard as i feared. It does look very intimidating, but the engine is actually quite bice to work on. Well layed out and most things are easy to get to with a little effort.

Sent from my SM-G920F using Tapatalk

 

[desertstorm]

Glad you got it sorted, I was surprised to see a thread like this that I hadn't commented on. I was on holiday back in Feb when this started.
Not sure why you are revving the car past 5K there is absolutely no point as the engine is well down on power at this point. You are more liable to cause issues with the cam chains and tensioners by running it any where past 5K.

 

[bobby singh]

Glad its finally fixed

 

[youngy93]

Was it easy to remove the belt as mine is due a change? cheers

 

[Sootpig]

Was it easy to remove the belt as mine is due a change? cheers

Easy peasy, just undo the 13mm and slacken the tensioner off (loosen the pump pulley nut first) then slip the belt off, no timing required

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[Bjørn Roger Larsen]

I have almost the same problem on my 2008 q7 3.0tdi.
It stalls when it reaches operating temp.
New HP pump, regulator, filter and crankposition sensor ...
If I unplug the temperature sensor, the fan blows all the time and the engine does not reach operating temp, resulting in no stalling...