High Pressure Fuel Pump issue?

[gillbe]

17 hours ago, Gramps said:

Anyone out there got any figures for fuel pressure when cold prior to start, ie just ignition on then same figure once it's fired up? Be interesting to see how they compare with mine. went to start it from cold tonight and my fuel rail pressure was about 150psi with ignition on, when statrted it rose to about 1100psi at fast idle, about 1100 rpm, then dropped down to 660psi or so when the tickover dropped. I also had all 3 error codes appear again, banks 1 & 2 too lean and P1094 ( Implausible Mass Air Flow Ahead Of Throttle Valve)  

Tried to get you these figures then when could not find the options on icarsoft realised probably not available as mine is the non DFI 2.9 987.2 !

Loosening my oil cap slightly also made it run like a dog.  Removing altogether was easy.

Re coils, was just fishing for some possible justification of the spend, as I have bought new whilst the old are still "sight unseen" , having done nearly 100K and can see never replaced from the extensive all-OPC records on my 13 year old model.  On their way from Autodoc via Evri, so expected any time next year...

 

[Gramps]

3 minutes ago, gillbe said:

Tried to get you these figures then when could not find the options on icarsoft realised probably not available as mine is the non DFI 2.9 987.2 !

Loosening my oil cap slightly also made it run like a dog.  Removing altogether was easy.

Re coils, was just fishing for some possible justification of the spend, as I have bought new whilst the old are still "sight unseen" , having done nearly 100K and can see never replaced from the extensive all-OPC records on my 13 year old model.  On their way from Autodoc via Evri, so expected any time next year...

 

Thanks for trying, much appreciated 👍. On my iCarsoft I went into OBD11, monitor overview, then scrolled down to live data. Once then you can just select the options you're interested in which makes things easier. But as you say if your's is not DFI then that option probably won't be there anyway? 

Strange how removing the oil filler cap can have that much of an effect on the smooth running. I think that part of the emissions controls means the engine is "vacuumed" so anything in there is spat out the rear. I remember not that long ago removing the oil filler caps with engine running just to check for any noise or sludge and the like, no doing that on these motors.

Yeh, still yet to see my coil packs, they may still be due for a change. Not seen anything my service history to say they've been changed at any stage. Cars now on 89k, so not far off yours. Are you getting any issues currently that makes youo want to change them?

[gillbe]

Re Are you getting any issues currently that makes you want to change them?

 

Only a feeling that car is running on a slightly uneven road surface at 30-35mph, when in fact the road is smooth.   This is on damp, rainy days.   Noticed the next day, with sunny weather and dry since the previous run, no such lumpiness.  So, that's what I'm hoping will go away with new coil packs.

Did not know about the live running OBDII section - always using the "Diagnostics" menu, thanks for that!

Edited April 6, 2023 by gillbe
icarsoft feature awareness

[iborguk]

1 hour ago, Gramps said:

Thanks for trying, much appreciated 👍. On my iCarsoft I went into OBD11, monitor overview, then scrolled down to live data. Once then you can just select the options you're interested in which makes things easier. But as you say if your's is not DFI then that option probably won't be there anyway? 

Strange how removing the oil filler cap can have that much of an effect on the smooth running. I think that part of the emissions controls means the engine is "vacuumed" so anything in there is spat out the rear. I remember not that long ago removing the oil filler caps with engine running just to check for any noise or sludge and the like, no doing that on these motors.

Yeh, still yet to see my coil packs, they may still be due for a change. Not seen anything my service history to say they've been changed at any stage. Cars now on 89k, so not far off yours. Are you getting any issues currently that makes youo want to change them?

An active codes since you tightened the oil cap ? 

[Gramps]

3 hours ago, gillbe said:

Re Are you getting any issues currently that makes you want to change them?

 

Only a feeling that car is running on a slightly uneven road surface at 30-35mph, when in fact the road is smooth.   This is on damp, rainy days.   Noticed the next day, with sunny weather and dry since the previous run, no such lumpiness.  So, that's what I'm hoping will go away with new coil packs.

Did not know about the live running OBDII section - always using the "Diagnostics" menu, thanks for that!

👍I find that if I go into the iCarsoft via Diagnostics menu it doesn't show me any fault codes though they are there???? But you can see the codes if you go in via the OBD11 option. If it sees any, and they are brand specific, it then asks you to drill down into make and model to find what the error is for. Not sure what version software you are running on your iCarsoft but I did post a short while ago to advise version 5 is now available to download.

Thanks again for your input...Rob

[Gramps]

2 hours ago, iborguk said:

An active codes since you tightened the oil cap ? 

Took the car out for some errands this afternoon wouldn't normally but wanted to see just that. And nothing popped up. Car started well (always less cranks when warm) and ran smoothly. Need to get out over the next couple of days when the sun's out and give it some beans, then see where we are. But good so far 🙂

[Richard Hamilton]

All I can find about the high pressure system is from the Service Technik:

"The direct fuel injection (DFI) used in the new flat engines is based on homogeneous direct injection. In this process, electromechanically controlled fuel injectors inject the fuel directly into the combustion chamber at a pressure of approx. 580 to 1740 psi (40 to 120 bar) and with millisecond accuracy as required by the respective driving state."

I believe some of the HP pump faults are actually attributed to a faulty sensor.   Also, the LP sytem can cause HP fault codes.  LP pressures are 5 bar (igniton on, engine off), with a holding pressure of 4.0bar after 20 minutes ignition off.

[iborguk]

48 minutes ago, Gramps said:

Took the car out for some errands this afternoon wouldn't normally but wanted to see just that. And nothing popped up. Car started well (always less cranks when warm) and ran smoothly. Need to get out over the next couple of days when the sun's out and give it some beans, then see where we are. But good so far 🙂

As you said previously a step in the right direction, maybe something else is in play.

Yes go use it in the sun  👍

[Gramps]

1 hour ago, Richard Hamilton said:

All I can find about the high pressure system is from the Service Technik:

"The direct fuel injection (DFI) used in the new flat engines is based on homogeneous direct injection. In this process, electromechanically controlled fuel injectors inject the fuel directly into the combustion chamber at a pressure of approx. 580 to 1740 psi (40 to 120 bar) and with millisecond accuracy as required by the respective driving state."

I believe some of the HP pump faults are actually attributed to a faulty sensor.   Also, the LP sytem can cause HP fault codes.  LP pressures are 5 bar (igniton on, engine off), with a holding pressure of 4.0bar after 20 minutes ignition off.

@Richard Hamilton Thanks for your input Richard. That figure of 4 bar on the low pressure side (20mins after ignition off) ties in exactly with what I see on the high pressure side with the same criteria. The HPFP is mechanical so seems reasonable to assume that the high pressure side could drop to the same as the low pressure side once the engine has stopped. Highest HP figure I've seen is about 1100psi. I assume the highest figure would only be seen with foot  to the floormaximum acceleration, and there's no way I'm trying to look at that myself whilst giving it some beans. Will have to get someone to ride shotgun with me, or try videoing it.

I believe Porsche are onto version 6 of the HPFP now (9A1-110-315-02 now supreceded by the 06 version), so it appears they've been mod'g the HPFP along the way.

Strange how those HP figures are so evasive on the web, but at least the figures I'm seeing when running fall within the range you've quoted, though my when running LP figure is quite near the quoted LP figure, but I guess that figure can only be gained with the engine running.

Thanks again 👍🙂 

[Gramps]

On 4/6/2023 at 10:34 AM, iborguk said:

How’d you get on ?

@gillbe @Paul P Have taken it out a few times now, including today when I was able to gve it some beans and no EMLs etc so looks like now all ok 🙂 , other than the prolonged cranking when cold, but I can live with that. Might stick my lithium jump starter on it next time just to see if it makes a difference. Still not had any live figures re the HP fuel rail but @Richard Hamilton Richard's input was handy