E89 Z4 HPFP nightmare

Neg89

Specialist
Jul 4, 2021
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Hello all folks.


So the snow has melted and i have opportunity to log the car, since last year when my tuner pureboost.de started to tune my car i encountered a HPFP dips at midrange on my N54 DCT. The car has TTE500 turbos, wagner ic, Catless dp, Inlets,Chargepipe, hidro steering, m4 brakes and so on.

In the winter i put in new genuine BMW HPFP
3x new genuine BMW injectors (the rest 3 i put in 2021) so all injectors is new.
Before that in 2021 fall i upgraded LPFP with walbro 535, which gave no difference.

Unfortunately the logs in 2022 show very low HPFP pressure. The pressure drops even to 700 psi So I decided to put in new oem fuel filter/pressure regulator.(yes it very funny to work on e89 fuel pump, yikes) It did not make any difference ether. Also tried the log with open fuel tank cap=no difference.

We are here

Injectors new.
LPFP new
HPFP new
Filter/regulator new
Running 98 fuel from different fuel stations

What else can it be?

I have observed that the first logs at WOT which i made (after warm up 40+ min drive) the HPFP drops . But little later when i make logs again at WOT the HPFP drops a significant amount more. At first attempts the log sowed dip to 1200psi, later on even 800psi. Once the pressure drops so low sometimes i get misfire on clinder 6 and cutout, i think because it is on the far end of the fuel rail. Other times it runs just fine but you and i now it is not good at all at so low HPFP pressure.

I am really stuck here, i really need some help. And of course z4 does not have lpfp sensor,which is another coincidence.


Any help?
 
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martymil

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Seeing how much boost your running you need to overdrive your HPFP as it can't supply enough fuel.

Get a PFS pod as that will fix your HPFP issues or turn down the boost.


This is the problem with e89's as you can't see what the LPFP is doing, put a low pressure fuel pump gauge on your LPFP so you can keep an eye on it under boost, you can tee into the low pressure side just before the HPFP.

Cylinder 6 misfire is due to the n54 DCT flywheel at that boost level, you might have to upgrade the flywheel to S55.

One more thing you can try as a band aid that will lift your HPFP pressures up slightly is remove the inline filter in the HPFP where the LPFP
fuel line joins it as its extremely restrictive.
 
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Neg89

Specialist
Jul 4, 2021
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Seeing how much boost your running you need to overdrive your HPFP as it can't supply enough fuel.

Get a PFS pod as that will fix your HPFP issues or turn down the boost.


This is the problem with e89's as you can't see what the LPFP is doing, put a low pressure fuel pump gauge on your LPFP so you can keep an eye on it under boost, you can tee into the low pressure side just before the HPFP.

Cylinder 6 misfire is due to the n54 DCT flywheel at that boost level, you might have to upgrade the flywheel to S55.

One more thing you can try as a band aid that will lift your HPFP pressures up slightly is remove the inline filter in the HPFP where the LPFP
fuel line joins it as its extremely restrictive.
Thank you for answer, do you have info on what type of lpfp sensor ? From n54, or alternarive, and connect to dme or other metod of logging?
 

Neg89

Specialist
Jul 4, 2021
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No different to any n54 and you will need a new tune.
I am a bit confused, as i run only pump fuel and no emix or something.Do i really run out of original fuel supply capabilities? Damn,really? Ekpm3 has nothing to do with this? If so. Do i need to put in pod thwn log and then request new tune or different order. I am from europe, the place to get the pod?
 

wheela

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Jun 4, 2021
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At 24 psi and no E yes your hpfp is on its limits, turn the boost down or overdrive you hpfp using a pod
Agree. The other option would be to add PI (instead of POD) but if it were my car, I'd do the POD overdrive to avoid adding more complexity to the system.
 

Neg89

Specialist
Jul 4, 2021
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Looked that i better install vacuum pumo plate together with this, the plate is cheap but in spool website shipping is 200$ whis is no no . Any oprions to get that in europe.?
 

fmorelli

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Aug 11, 2017
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@martymil is on point. The HPFP is at limits, as well you didn't mention what you are using as an LPFP. Given you went in and did the regulator, I assume you have an upgraded LPFP? As for sensor, we don't have it. There are people that have integrated it - I have not. There are some threads here but it requires some technical knowledge to do so (there is not an enumerated set of steps posted anywhere).

I'm also going to assume factory turbos (since you don't say anything else). Drop down to about 19psi and see how things go.

If you want to upgrade your setup to run more power - that's a separate conversation, so to speak.
 

Neg89

Specialist
Jul 4, 2021
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@martymil is on point. The HPFP is at limits, as well you didn't mention what you are using as an LPFP. Given you went in and did the regulator, I assume you have an upgraded LPFP? As for sensor, we don't have it. There are people that have integrated it - I have not. There are some threads here but it requires some technical knowledge to do so (there is not an enumerated set of steps posted anywhere).

I'm also going to assume factory turbos (since you don't say anything else). Drop down to about 19psi and see how things go.

If you want to upgrade your setup to run more power - that's a separate conversation, so to speak.
As mentioned in first post tte500 turbos,535 fuel pump.
 
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martymil

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I personally would wind back the boost to 21psi especially on a stock motor as you will lift the head eventually as many of us have found out.

That will solve your fuel issue, stop the 6 cylinder misfire and make your motor last

Most of us been where you are and they are not bulletproof
 

Neg89

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Jul 4, 2021
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I personally would wind back the boost to 21psi especially on a stock motor as you will lift the head eventually as many of us have found out.

That will solve your fuel issue, stop the 6 cylinder misfire and make your motor last

Most of us been where you are and they are not bulletproof
You mean blow head gasket? I was thinking i have moderate power level.
 

martymil

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You mean blow head gasket? I was thinking i have moderate power level.
No You will stretch the factory head bolts and lift the head of the block.

its not about the power level, its cylinder pressures and many have found out the hard way.

21psi is about as much as you want to run on a stock motor with stock head bolts.
 

Neg89

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Jul 4, 2021
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Fck. No way i want tu run 21psi. That would be no power at all. So what options we got in 2022 for standart sized head bolts/studs. No intention to go further in HP means thanbi am now,just to make it reliable. Standart size or ovesize studs?Engine must be taken out and stripped to what level? Fck. Seriously.?
 

martymil

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They start to lift heads at your boost level your at now its only matter of time.

Put a OD on the hpfp and hope it lasts as your in for a rebuild with a min of forged rods, pistons and arp head studs to make it reliable.
 

Neg89

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Then i will ned pod anyway.:hearteyes: THIS thing is getting more and more expensive.Ok.so if i ask the tuner to leave 22psi max, maybe i can just leave it as is.No pod,no studs,no pistons etc.? Not shure i want to put in (even not knowing how much money?) .
 

martymil

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It will depend on your hpfp on how much boost you can run without your fuel pressure tanking, you don't want to misfire either as you might crack a ring land and cause piston failure.

21psi is the sweetspot for a long lasting stock motor.
 
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fmorelli

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They start to lift heads at your boost level your at now its only matter of time.

Put a OD on the hpfp and hope it lasts as your in for a rebuild with a min of forged rods, pistons and arp head studs to make it reliable.
And then there is the crank hub ....

Do you have access to ethanol?
 
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pbondar

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So what sort of crank BHP can you expect of an E89 N54 running TTE500s (or similar turbos) on 98 Ron fuel before you run out of HPFP at 21 PSI ( if that’s the limit for stock motor studs)?