Splutter under hard acceleration

[TomC]

Looking for help on a problem. Car's currently in being repaired after a minor front end crash (not my fault).

Repairer has put it all back together. The car drives well except for one issue. Under WOT car boosts up to around 3500/4000 rpm and then splutters, exactely like it's not getting enough fuel. Scanned for error codes and came up with "low fuel pressure control outside normal parameters". Dealer replaced a fuel sensor but no fix. They are not prepared to go any further as the car is tuned.

The repairer is at a loose end. I'm going over to set computer back to stock tune and see if that fixes it. It sounds like a dodgy fuel pump to me. The thing is, it was fine prior to the accident so is there a chance it was damaged in that somehow?

I'd apprecaite any wise thoughts/help!

[zhifchik]

The car drives well except for one issue. Under WOT car boosts up to around 3500/4000 rpm and then splutters, exactely like it's not getting enough fuel. Scanned for error codes and came up with "low fuel pressure control outside normal parameters". Dealer replaced a fuel sensor but no fix. They are not prepared to go any further as the car is tuned.

I'd apprecaite any wise thoughts/help!

I have exactly the same issue and same error code. Didn't want to go to the dealer with a Stage 2+ kit and tune so I was going to put my own Bosch 044 pump in until I realised the pump needs to be wired into the CANBUS and is driven by the low pressure fuel sensor. It was time to sit down, map it out and plan accurately before acting.

Will watch your solution with interest. Will also share any of my findings.

NOTE: It doesn't happen at the track when you are up in the revs at all times. It's only the mid range, typically accellrating away from the track environment.

[TomC]

Update: just been to repairer. Reset ECU back to stock. He took me for another drive and problem still exists. It's not a splutter - more a hard cut - anywhere around 4000rpm and only under WOT. It spools up fine if you feed the power in.

The following entries were logged in the ECU:
12555 P310B Low Fuel Pressure Control
04767 P129F low fuel pressure system, pressure too high
00135 P0087 fuel/system pressure, too low.

[Transporter]

Where in Adelaide are you?

[TomC]

Where in Adelaide are you?

Have sent you a PM Transporter

[NabzGTI]

Have sent you a PM Transporter

I had a similar issue, and vagcom returned something about cylinder 1.. i assumed a coil pack.

After annoying the daylights out of me.. I pushed it real hard once and came up with multiple CEL's. I reset the codes and been perfect ever since (as if the computer learnt something new).

[mk5fsi]

I'm Having the same Problem, however it happens under load and WOT, after some searching around it, the problem could be because of a worn out cam follower. As i understand the High pressure fuel pump, runs of the camshaft, since the cam follow is probably worn, it slips, meaning that the high pressure pump doesn't work therefore causing a fuel cut. Anyone that can shed light to this please do.

[Transporter]

...or leaking PCV.

[TomC]

Thanks all for your reply. I had the PCV done 5000km ago as a precaution so I doubt it would be that.

Could be a worn cam follower although at 61k that would seem funny and I don't thrash the car by any means. I did think it might be the fuel pump but normally you'd expect quite a stutter with fuelling wouldn't you? It's really just a hard cut and lunge at which point the repairer pulled out of the power. But given the codes that were logged, it'd have to be something fuel related? Interestingly though, no dash lights appeared, which surprised me...

Still, will pass this all on to repairer for investigation. Thanks all, keep it coming

[zhifchik]

Update: just been to repairer. Reset ECU back to stock. He took me for another drive and problem still exists. It's not a splutter - more a hard cut - anywhere around 4000rpm and only under WOT. It spools up fine if you feed the power in.

The following entries were logged in the ECU:
12555 P310B Low Fuel Pressure Control
04767 P129F low fuel pressure system, pressure too high
00135 P0087 fuel/system pressure, too low.

As mentioned, same issues.
My fault codes were
12555 Low Pressure Fuel regulation P310B - 002 - Fuel Pressure Outside Specification - Intermittent
004688 - Fuel Level too Low P1250 - 008 - Andrew you kent, don't do laps with such a low fuel load - Fix It Bustard
012425 - Signal Line for Fuel Pump Electronics - P3089 - 004 - Electrical Malfunction - Intermittent

H'mm, off to trawl the VAG forums on Rosstech and VWWC

[TomC]

Bumping this up top - still appreciate any thoughts if you haven't chipped in yet

[h100vw]

Bumping this up top - still appreciate any thoughts if you haven't chipped in yet

I reckon logging the rail pressure would be worthwhile.

Measuring blocks fuel pressure 2, 230 and 231,( boost 3 115, 118, ignition 2, 20, 22, fuelling 2, 31, 99.)

Probably worth doing the fuelling too.

Run it in 3rd gear if you can, from 1500 revs until it plays up, with the throttle wide open.

I have logs of other modded MK5s to compare with.

Gavin

[TomC]

Thanks Gavin, this is very helpful. Will pass it straight on.

[h100vw]

PM me an email address and I'll send you a log of a Phase 2 MK5 to compare with.

Gavin

[TomC]

Update: Just come back from AVW (who work closely with the crash repairer) and they discovered a small particle of dirt in the HPFP which, every time you really kicked it, would stop the full flow of fuel getting in.

They couldn't really work out how it would have got in there, but the crash repairer suspects it might have happened during the removal and then replacement of the engine during the repair process. Has anyone had this happen?

Anyway, great outcome because it means I can get my car back tomorrow