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      10-09-2010, 04:39 PM   #89
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Quote:
Originally Posted by VintageBMW View Post
Thanks - I have already written the dealer and requested the part - we shall see.
If they were on notice of of your potential claim and they no longer have the part, they have a real spoliation problem on their hands.
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      10-09-2010, 04:59 PM   #90
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Originally Posted by VintageBMW View Post
Thanks - I have already written the dealer and requested the part - we shall see.
You paid for the HPFP when you bought the car. It is yours. They are only allowed to retain old parts replaced under warranty - per the wording in the warranty.
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      10-09-2010, 05:07 PM   #91
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Service station suppliers will sometimes share product from for example Shell, with Petrocanada if the Petro Canada tanks run out. It's all the same base product, the additives are mixed in when the truck loads. All these discount stations get their gasoline from the same big producers but use different additives. All our main refineries are in Edmonton, we have tank farms in Calgary.
The ethanol blends would be a bit different.

As for seals in HPFP's, those of us that work in the petrochemical biz know that anything manufactured for use in our plants can come many different ways, configured for whatever product it needs to work in. It could be sour liquid, it could be sulphur or any number of things. An HPFP is no different, the damned things probably use some part mfg'd in some 3rd world country with little or no QC at the factory. A bad production run of one part can basically wreck an entire product line for years to come if not caught. That is why we have recalls.......and that is what BMW needs to do. Much like Ford , it is easier to wait and fix it when it's broke instead of recalling all the 35 series HPFP's, unfortunately we may need to have deaths attributable to it before anything else is done.
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      10-09-2010, 05:17 PM   #92
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Quote:
Originally Posted by warden View Post
If they were on notice of of your potential claim and they no longer have the part, they have a real spoliation problem on their hands.
you have given yourself away as a lawyer with the use of the word "spoliation," and I agree with you 100% - I know there are a lot of lawyers among us
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      10-09-2010, 06:54 PM   #93
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Quote:
Originally Posted by Silver-Bolt View Post
Teague,
I need to do more research on the N54 DI fuel system to fully understand how it operates. Typically in boosted application the fuel pressure is constant but the flow varies.

Here is a question I cannot find any information on. What fails in the HPFP? Seals, impeller, etc? Anyone had a bad pump apart to see what is actually failing? Ethonal is extremely hard on fuel systems and especially "rubber" components. I racing applications it takes a completely different fuel system to run alcohol including the fuel pump. Could the U.S. mandated ethonal be contributing to the HPFP failures?

Vintage,
If you happened to get the failed pump from your car you may be able to make your case by having it tested to diagnose what within the pump let go.
From the engineer dept. BMW N54 uses a Siemens Piezo GDI (gasoline Direct Injection) system. See the following links FYI. Photos and a simplified descrition of the system that even the lawyers can understand - just kidding!! The pump details are interesting 20 Mpa = 2900 psi.

The high-pressure fuel pump is a multi cylinder axial piston pump. The pump is mechanically driven by the engine. It is separated into two parts, the completely sealed oil chamber and the part that contains fuel. The oil and fuel halfs are separated from each other by a membrane. A swash plate transfers its rotation into axial strokes of the pistons, each of which are guided in a cylinder. The oil pressure is transferred from the oil to the fuel via the membrane, the fuel is fed to a common fuel rail, and then to the injectors.

http://www.n54tech.com/forums/showthread.php?t=8774


http://www.ae-plus.com/Key%20topics/...rain-news5.htm
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      10-09-2010, 07:38 PM   #94
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Silver-Bolt earlier I posted the comment to you.

Quote:
Originally Posted by teagueAMX View Post
Silver-Bolt, I considered that as well. I know that older fuel pump designs pumped a constant amount of fuel regardless of engine output. For BMW to make the case you're suggesting they would have to prove the pump varies pressure based on demand, however, I don’t think that’s case. If the pump is a constant pressure then they don’t have a leg to stand on concerning the FMIC. We’d need to talk with a BMW mechanic to verify.
HerrK's information supports that the HPFP produces a constant pressure based on RPM. This is critical to Vintage's case because the failure of the pump has nothing to do with how much horsepower the engine is producing.

Therefore, he can say the FMIC did not cause the engine or the HPFP to operate outside it's normal range. The failure of the HPFP is a result of it own poor design
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Last edited by teagueAMX; 10-09-2010 at 07:56 PM.
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      10-09-2010, 07:59 PM   #95
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The pistons rotate with the swash plate which is driven by a shaft/gear to the engine. The tilt of the swash plate (yellow) can (as in hydraulic pumps running at fixed RPM) be varied to vary the displacement (output) of the pump. In this case the swash plate is probably fixed and the out put increses with RPM.

The pressure is an effect of the inlet and outlet fluid porting - as the swash plate and pistons rotate the displacement is varied thus as the volume decreases the pressure increases.

Just as in the 19" 296 wheels - the "cause" of the HPFP failures has multiple paths. Poor internal dimensional control, seal failure, poor material, etc.



I still love my N54 and its technology. So on occasion it may fail. C'est la vie! Having been associated with BMW Mottorad problems for 30+ years I know and live with the following.

1. BMW do not like to admit to their mistakes publicly.
2. Sometimes it takes them a few years to correct their problems.

The pump is probably very sensitive (maybe overly so) to heat from the oil. Incresed performance = increased oil temp, which may lead to incresed failure rate. Which is probably how BMW will defend their warranty on this component.
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      10-09-2010, 11:12 PM   #96
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HerrK, as a testing engineer tell me what you think.

Of course the side of the pump connected of the engine is going to get plenty of lubrication, but the other side will be lubricated by the fuel itself. Now we know that gasoline (petrol) provides adequate lubrication for simple electric fuel pumps, as this is evident by the millions of in-tank pumps out there with thousands of miles on them.

The BMW HPFP seems to be a very complicated mechanical device to on rely gasoline (petrol) to provide adequate lubrication. Just my personal observation based on a poor quality photo, but if you look closely at the darkened color of the piston plungers sticking out of the device it appears they've experienced a fair amount of heat and inadequate lubrication.

I know the ethanol question is still out there but I'd really like to focus on the question of pump lubrication on the fuel side.

.
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Last edited by teagueAMX; 10-09-2010 at 11:35 PM.
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      10-10-2010, 08:46 AM   #97
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Herr & Teague,
This is good stuff. Sounds like we can rule out the membrane failing as we would end up with fuel in the oil and likely a bunch of smoke out the tail pipe. The parts do appear as if the have been hot but gasoline will auto ignight at 495f.

I have also read about many of the low pressure intank pumps either failing of becoming noisey. Perhaps the real issue is not sufficient volume of fuel reaching the HPFP causing it to overheat. If the intank pump is not replaced, replacing the HPFP will just be a bandaid. It will continue to fail until is has a constant supply of fuel.
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      10-10-2010, 11:16 AM   #98
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I love every word of this discussion - it is very helpful and I appreciate the help.

As for the higher performance = higher oil temp, which could contribute to HPFP failure; I guess this may be true and I am no engineer, but if that is what caused my HPFP failure, why is it that many N54 powered cars don't even come with an oil cooler from the factory to this day, including e89s. That would almost guarantee failure.
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      10-10-2010, 12:49 PM   #99
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Quote:
Originally Posted by Silver-Bolt View Post
Herr & Teague,
This is good stuff. Sounds like we can rule out the membrane failing as we would end up with fuel in the oil and likely a bunch of smoke out the tail pipe. The parts do appear as if the have been hot but gasoline will auto ignight at 495f.

I have also read about many of the low pressure intank pumps either failing of becoming noisey. Perhaps the real issue is not sufficient volume of fuel reaching the HPFP causing it to overheat. If the intank pump is not replaced, replacing the HPFP will just be a bandaid. It will continue to fail until is has a constant supply of fuel.
I agree.

I speculated a couple of months ago (looking for thread now) that the HPFP is failing as a result of loss of pressure from the in-tank low pressure fuel pump (LPFP).

I believe BMWs split fuel tank contributes somewhat to this problem. When a car has a full tank of gas and goes around turns, goes up and down hills, stops and starts it’s not much of a problem. But as the tank level gets low the fuel “sloshes” from front to back and side to side – away from the in-tank pump fuel pickup. Getting down to a quarter tank or less really makes this worse. The engineers came up with a solution and that is to put the in-tank pump in a slosh cylinder or canister that’s open on the bottom to receive fuel, but as the tank tilts with movement some of the fuel is captured within the cylinder to prevent the pump from going dry.

This is a good design, but BMW has defeated this somewhat but using spit fuel tanks. The advantage is a more compact car design, lower center of gravity, etc. However, a low fuel problem is compounded somewhat by splitting the supply between the two sections of tank. So when you get down to a quarter tank of gas, you’re really only have one-eighth in each tank. They sort of solved it by using a remote pickup, but. . .

A low fuel supply is the primary reason in-tank electric fuel pumps fail and that’s due to a lack of fuel for lubrication, damaging the internal bearings and they overheat. You can imagine that over the lifetime of a car, in-tank full pumps experience hundreds if not thousands of low fuel situations but they are built tough to withstand it for 70- 80 thousands of miles before they fail.

Now let’s fast forward and talk about the Z4’s HPFP. We know the LPFP sends a pressurized flow of fuel to the HPFP, which in turn further boosts that pressure to a monstrous 2900 PSI (as HerrK discovered) for the direct injection system. To say the HPFP is entirely dependent on the LPFP is an understatement. Not only does it impact the fuel supply to the injectors, but IMO and more importantly, has a major impact to the life of the HPFP.

Finally seeing the HPFP guts exposed shows IMO that it’s severely over designed, and I agree with HerrK that is could be very “sensitive”. A pump of this type must have extremely close mechanical tolerances, and imagine it must maintain those tolerances over the life of the unit, nearly impossible in less than idea conditions. IMO a low fuel situation, results in LPFP cavitation and surging within the fuel line prior to the HPFP. This results in shock waves in the fuel supply line, thus starving the HPFP of much needed lubrication and the pump overheats. The little pistons and cylinder walls are scored, seals are damaged and the unit no longer meet spec to enable it to produce 2900 PSI. Whalla – long cranks and limp mode.
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Last edited by teagueAMX; 10-15-2010 at 01:45 PM.
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      10-10-2010, 01:28 PM   #100
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Quote:
Originally Posted by teagueAMX View Post
I agree.

I speculated a couple of months ago (looking for thread now) that the HPFP is failing as a result of loss of pressure from the in-tank low pressure fuel pump (LPFP).

I believe BMWs split fuel tank contributes somewhat to this problem. When a car has a full tank of gas and goes around turns, goes up and down hills, stops and starts it’s not much of a problem. But as the tank level gets low the fuel “sloshes” from front to back and side to side – away from the in-tank pump fuel pickup. Getting down to a quarter tank or less really makes this worse. The engineers came up with a solution and that is to put the in-tank pump in a slosh cylinder or canister that’s open on the bottom to receive fuel, but as the tank tilts with movement some of the fuel is captured within the cylinder to prevent the pump from going dry.

This is a good design, but BMW has defeated this somewhat but using spit fuel tanks. The advantage is a more compact car design, lower center of gravity, etc. However, a low fuel problem is compounded somewhat by splitting the supply between the two sections of tank. So when you get down to a quarter tank of gas, you’re really only have one-eighth in each tank. They sort of solved it by using a remote pickup, but. . .

A low fuel supply is the primary reason in-tank electric fuel pumps fail and that’s due to a lack of fuel for lubrication, damaging the internal bearings and they overheat. You can imagine that over the lifetime of a car, in-tank full pumps experience hundreds if not thousands of low fuel situations but they are built tough to withstand it for 70- 80 thousands of miles before they fail.

Now let’s fast forward and talk about the Z4’s HPFP. We know the LPFP sends a pressurized flow of fuel to the HPFP, which in turn further boosts that pressure (as HerrK discovered) to a monstrous 2900 PSI for the direct injection system. To say the HPFP is entirely dependent on the LPFP is an understatement. Not only does it impact the fuel supply to the injectors, but IMO and more importantly, has a major impact to the life of the HPFP.

Finally seeing the HPFP guts exposed shows IMO that it’s severely overdesigned, and I agree with HerrK that is could be very “sensitive”. IMO a low fuel situation, results in LPFP cavitation and surging within the fuel line prior to the HPFP. This results in shock waves in the fuel supply and starves the HPFP of much needed lubrication and the pump overheats. The little piston cylinder walls are scored, seals are damaged and the unit no longer meet spec to enable it to produce 2900 PSI. Whalla – long cranks and limp mode.
This sounds like the most likely explination. I have seen standard in tank pumps fail very quickly (matter of seconds) when run dry. They rely 100% on the fuel for both cooling and lubrication. Inside the pump are radially mount blades/fins that spin within a cylinder. It is capped on each end by plates that also come in contact with the fins. Any scores of groves in those plates result in the loss of pressure as well as volume. In racing applications we worked around this by creating a sump and the bottom of the fuel cell that contained the pump. The sump and a trap door that allowed fuel but it could not splash out during cornering, accel/braking/etc. Watching a race when you see cars low on fuel weaving back and forth they are attempting to get the last bit of fuel into that sump.

To prove the theroy with the BMW HPFP we would have to monitor the fuel pressure from the tank to the HPFP. Observe if that pressure changes as the tank is drawn down. My bet is below 1/4 tank the pressure will begin to fluctuate as the fuel sloshes in the tank. This may aslo show as a lean condition in the cylinders as the HPFP begins to fail.

If the oil temp was truly the issue we would also see a large number of turbo failures and possibly engine failures.
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      10-10-2010, 06:49 PM   #101
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I have read on other forums that LPFP's are being replaced first with some success. Haven't had much time to look into this further. But from the pump description the engine oil provides all the lubrication for the moving axial pistons/rotating cylinder. I believe the HP oil (output from the axial pump) is pushing on a diaphragm much like a LP mechanical fuel pump. Although in this case the diaphragm is probably metallic.
Agree it is probably not the diaphragm failing fro the fuel/oil mix reasoning. I don't think that failure or low supply by the LPFP would physically affect the HPFP - other than lack of fuel. From my searching, the axial HPFP's are very propietary as there is not much public info. It would be intereting to tear into one of these and see how they work. Unfortunate that whoever took the photos did not provide any documentation. Although this looks like the oil end of the pump - the cover (which appears to be the fixed swash plate) has an inlet and outlet port. The fuel pressure regulating portion of the pump may be failing. Anyway it is a beautiful afternoon in SoCal and I think I'll go out now and test drive my n54 HPFP to make sure its still working OK.

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      10-11-2010, 03:48 AM   #102
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So, if all this hypothesis is correct - I would imagine that BMW will argue that the increased performance mods on cars will increase the fuel load required* from the HPFP, which in turn increases the probability that the LPFP will be able to keep up enough supply to keep the HPFP lubricated.
HEnce increased chance of HPFP runnign dry, and overheating, and failing as a result....

Lucky it is just a theory.

If you are taking them to court will you subpeona their corporate records on the number and exact diagnosis of HPFP failures?

* Increased performance = more fuel usage. Fact of life.
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      10-11-2010, 09:56 AM   #103
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Quote:
Originally Posted by Dr Stig 2 View Post
So, if all this hypothesis is correct - I would imagine that BMW will argue that the increased performance mods on cars will increase the fuel load required* from the HPFP, which in turn increases the probability that the LPFP will be able to keep up enough supply to keep the HPFP lubricated.
HEnce increased chance of HPFP runnign dry, and overheating, and failing as a result....

Lucky it is just a theory.

If you are taking them to court will you subpeona their corporate records on the number and exact diagnosis of HPFP failures?

* Increased performance = more fuel usage. Fact of life.
Stig,
Not quite as black & white as that. Tuning for increased performance in some cases will actually increase fuel economy. Really depends on what the stock tuning is. D/I motors I am still very new too and just learning what makes them work. My current tuning experience is with tradition injectors. With those I can data log and monitor exactly how much of the injector capacity is being used. Not sure that is possible with a D/I setup. The big thing hurting BMW by claiming the mods caused the failure is that 100% bone stock cars are having the same failure and BMWNA extended the warranties on the cars in question.

Another aspect to consider is that the fuel enerting the HPFP is at ambient temperature and the oil lubricating the HPFP is at 250f. That is a huge temperature differential to have withing the same casting.
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      10-11-2010, 11:27 AM   #104
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The big thing hurting BMW by claiming the mods caused the failure is that 100% bone stock cars are having the same failure and BMWNA extended the warranties on the cars in question.
This will prove their undoing in the litigation - that coupled with the fact that no real testing was done on my HPFP to determine the actual physical failure in the pump, which may indicate the cause.
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