Hello, I own a MY2012 vrs 2.0 tsi dsg with 140k km.

 

A year ago at 130k km my HPFP started leaking fuel into the cylinder head so I replaced it with a new Pierburg unit and did an oil service. The cam follower (with roller) and cam looked OK and I didn't replace those.

 

Now I'm getting a p0087 code. I run some logs and saw my high fuel pressures drop (actual) vs the requested pressure. Specially under load/acceleration. 

 

While accelerating I get misfires and a strong hesitation. These coincide with the pressure drops.

 

Also, I now noticed a chirping noise from the pump which goes away if I unplug the solenoid on the pump, but the pressure shoots up to over 120bar (which leads me to believe the pressure sensor is fine).

 

If I'm very gentle with the throttle I don't get these cutoffs and the pump seems to be able to keep up with the requested pressure.

 

The symptoms are more evident when the engine is cold. After 25min of highway driving they are barely perceptible.

 

This started happening soon after I did a carbon cleaning. I also did an injector reaseal and scraped off some carbon from the injectors with a brass brush.

 

Is it possible my Pierburg pump is bad after 1 year and 10k km?

I still have the original pump. Could I swap the solenoids?

 

I ordered a new INA Cam follower just in case too (20usd at rockauto). The chirping sound has me worried that the roller might be stuck or something.

 

 

I also ordered a new 6.6bar fuel filter.

 

I forgot to mention that my LPFP primes ok and Vcds shows 6.5 bar when I open the door (engine off). But the LPFP duty cycle with the engine running is at 79.8% constantly, regardless of load rpm etc.

I read that stretched timing chains could cause issues with the HPFP.

 

I just read -4.51º intake cam phase angle.

This seems to indicate a stretching chain but it hasn't reached the ±5º limit I read somewhere.

 

Also, I noticed that the chirping noise gets louder if I unplug the solenoid (boosting rail pressure) and goes away when replugging it for some seconds (until the actual pressure reaches the specified pressure). Then it starts again.

 

This showes me that the HPFP under load makes the camshaft or itself noisy. I can't remember the "normal noise" for the HPFP.

 

Further analysis my logs and symptoms; it feels as the fuel system isn't able to keep up the requested pressure at higher flow rates (higher rpms and load).

The injector cleanup might have improved flow and worsen the situation.

 

I still can't understand why it goes away after 25min of driving.

 

Hello everyone,

 

2 weeks ago I tested the low side pressure near the HPFP inlet. My understanding is that it should be 6.6 bar but it oscillates around 3.5bar and then jumps to 6.5bar for a while. I believe the oscillation is due to the HPFP being a piston pump creating pulses.

 

Here are some videos of my testing. Note that the pressure jumps to 6.5bar sometimes when revving. The video shows the needle slowly oscillating but this is a video effect only. It was jumping very fast in reality.

Fuel Pressure testing 1

 

I read that somewhere that a guy with an A3 had a pump control module fail and had symptoms similar to me. This guy's LPFP barely sounded before the module replacement, sometime ago I thought that mine was very quiet so this might be a suspect.

 

I'll start by replacing the filter as the regulator might be failing, then I'll swap the pump control module.

 

PS: I believe the noise the HPFP is making is cavitation due to low pressure on the inlet side (the needle jumping reached 0 at times).

 

 

Hello,

 

I believe I fixed 99% of my issue:

-I replaced the pump module with a Vika unit -> LPFP noise changed (not louder, just different) but sputtering and hesitation still violently present.

-I replaced the fuel filter with a Xenst unit -> Problem almost completely gone!

 

I believe I have a weak LPFP as I can still feel some misfiring under load at 2k aprox. Its barely noticeable.

The fuel pressure at the HPFP still behaves the same as in the video but I noticed this:

 

When cold:

- LPFP duty cycle: 48-50% (after new filter).

-Fuel pressure: ~3.5bar

 

When warm:

- LPFP duty cycle: 78% (after new filter).

-Fuel pressure: ~6.5bar but increasingly "jumpy needle"

 

I've seen that the more the HPFP works (n276 valve off) the more the needle on the pressure gauge jumps and more noise it makes. So my theory is that the ECU is trying to compensate a low flow from the LPFP with the HPFP.

That would make the HPFF make noise at idle and could make low fuel pressure at the rail at high demand/low rev scenarios (HPFP not being able to compensate and supply the required fuel).

 

I've read that on a warm engine at idle LPFP duty cycle should be under 50% ideally. Over 70% indicates a weak LPFP or internal leak.

 

 

 

So yesterday on my way back from work I was logging fuel pressures, fuel pump duty cycle, and cam phase.

 

I read somewhere that a stretched chain could cause fuel pressure issues. I'm at 4.38° which isn't great but issues seem to appear on the 4.8° mark on.

 

Currently my HPFP pressures are on point during city driving. At WOT they dip up to -8bar and even the LPFP duty cycle rises to 85% approximately. 

 

I believe I have a weak LPFP as the problem almost disappeared with a filter replacement but is still somewhat present at high fuel demands.

 

So I didn't fix my issue...

 

My previous log was on an almost empty tank. Yesterday morning, just before I got to my office I filled up. On my way back home I felt a loss of power and logged the rest of the way.

 

At low loads and hi-ish RPMs (70km/h on 3rd) the fuel pressures becomes very erratic.

At WOT, the pressures just fall to 10bar and I have no power (before the filter replacement I would get a massive hesitation).

 

I believe the LPFP is bad as only my fuel level changed between logs and I can only see the LPFP being affected by it somehow.

Edited 6 June, 20241 yr by Etche
Add low pressure value info

Replaced LPFP last friday. I thought I fixed it but I got a similar log as on the 5th of june and later testing showed that symptoms still persists.....

 

Last night I removed my HPFP to replace the Cam Follower (roller type) as I saw a video of a 1.4 with my noise and issues. The original follower looked OK, I still replaced it with an INA unit (OEM).

I tried cleaning my HPFP by energizing the solenoid and spraying injector cleaner (I saw a video of rs4 pumps being cleaned like this). This didn't help either.

 

Comparing my Pierburg HPFP (10k km) to my old HPFP (Original) I found that:

• The Pierburg has a thinner rod.
• The Pierburg has a shorter stroke.
• The Original had its brass fitting cut for some reason.

My conclusions are:

• The shorter stroke causes follower slap and the "chirping" noise and lowers its flow.
• The Pierburg rod might be slightly bent and not allowing it to extend its full stroke. Once the pump housing is warm the rod can extend some more and the noise and symptoms decrease.
• During carbon cleaning a piece of carbon might have gotten into the HPFP limiting its extension somehow.
• The slapping might have worn my Camshaft. Upon inspection I didn't feel anything.

I just ordered a Hitachi HPP0010 (OEM pump) to replace my current one. It should arrive in a couple of weeks. I'll update my findings.

I fixed my issues. It was the HPFP.

 

I replaced my Pierburg unit with a Hitachi HPP0010 (oem). 

 

It wasn't without mishaps though... It arrived with the connector busted. I could wait another month for another and pay around 150USD JUST ON DUTIES AND SHIPPING or try and fix the connector. Thankfully all the pieces were in the box and I glue the connector puzzle back.

 

Looking back, I should have started by taking the Pierburg HPFP out for inspection. It did sound rattly and I thought it was overworking due to a weak LPFP, clogged filter, or bad LPFP module because it only had 1 year of use.

 

Removing and installing the HPFP is a 30 min job at most if its your first time.

 

I might swap back the original LPFP as it had a bigger baffle but keep the new module because it had a heatsink that the oem didn't.

 

I haven't checked VCDS but I'll try to post the new logs when I do.

 

Last Update: has been working fine these last months.

 

Some logs after the hpfp replacement:

 

 

 

Please mark as solved.