[wings516]

Tried finding advice on this, even asked indies and dealers to no avail, dealership even ran "diagnostics" for the fuel system and said it could be the HPFP or injectors. Symptoms started 12/2023, CELs for low/out of limits fuel pressure, poor start, hesitation on acceleration, crap gas mileage. Car was not a candidate for the HPFP recall.

Car: f30 328dx 197k, SCR delete, stage 2 tune, afe intake, buzzken exhaust

Fast forward to a month ago, ended up replacing all injectors, CELs went away, MPG restored, all is well, except the hesitation from stop is still VERY present. Ran an xHP TCU tune to see if it was tranny related, no luck there despite various tinkering like decoupling, 2nd gear start. No loss of power under WOT, no stuttering, no CELs.

Hoping to get some new ideas on where to look or if this even could be HPFP related.

[armend195]

Hello, i will be following your thread as i’m experiencing similar issue.
On mine, when reading live data, the fuel rail pressure is unstable and erratic jumping anywhere from 25000kpa to 32000kpa. Check yours too so we can see if we have same issue. I’m also worried that it might be hpfp related.
I changed the fuel rail pressure sensor and it didnt help. Now planning to change fuel pressure regulator sensor on rail, and further down the road the quantity valve on the pump itself.

Hope you get it sorted

[TurboWeasel]

At 197K, I would suspect the lift pump in the tank is tired. If that isn't feeding enough fuel to the HPFP, it will struggle to meet the commanded rail pressure, but measured pressure doesn't always tell the full story. It's the flow rate that suffers when the feed pump is weak.....which isn't monitored. Only the rail pressure and injection quantity is.

Assume you've been doing the fuel filters on time and not using the cheapest, dirtiest fuel available?

[wings516]

Originally Posted by TurboWeasel

At 197K, I would suspect the lift pump in the tank is tired. If that isn't feeding enough fuel to the HPFP, it will struggle to meet the commanded rail pressure, but measured pressure doesn't always tell the full story. It's the flow rate that suffers when the feed pump is weak.....which isn't monitored. Only the rail pressure and injection quantity is.

Assume you've been doing the fuel filters on time and not using the cheapest, dirtiest fuel available?

Fuel filters have been routine. Typically Sheetz diesel with intermittent Kroger. Same CEL's just reappeared yesterday.

I will probably consider replacing the tank pump at this point given my mileage, as well as the HPFP. The only other thing I am considering is getting a smoke test.

[barf]

I would replace both fuel pressure regulators and sensor first before replacing HPFP since they are quite cheap and not hard to replace. Pierburg or Bosch sensors are fine to use, no need for OEM - one of them is OEM.
Proper logging of the car would result in more information but since its quite impossible to do well online I would just recommend replacing the sensors and regulators first.

[wings516]

Originally Posted by barf

I would replace both fuel pressure regulators and sensor first before replacing HPFP since they are quite cheap and not hard to replace. Pierburg or Bosch sensors are fine to use, no need for OEM - one of them is OEM.
Proper logging of the car would result in more information but since its quite impossible to do well online I would just recommend replacing the sensors and regulators first.

These two?
Sensor: 13537800602
Regulator: 13537801992

[TurboWeasel]

Originally Posted by wings516

Fuel filters have been routine. Typically Sheetz diesel with intermittent Kroger. Same CEL's just reappeared yesterday.

I will probably consider replacing the tank pump at this point given my mileage, as well as the HPFP. The only other thing I am considering is getting a smoke test.

Good man

Maybe get the in-tank pump pressure tested first, before getting the parts cannon out. I'm not sure if the low side pump is PWM speed controlled, or a flat flow rate.

Have you got ISTA? It comes with instructions for most jobs and there might be a BMW procedure for testing it.

The low and high side pumps are expensive, so we need to fire the right part(s) at it!

[wings516]

Originally Posted by TurboWeasel

Good man

Maybe get the in-tank pump pressure tested first, before getting the parts cannon out. I'm not sure if the low side pump is PWM speed controlled, or a flat flow rate.

Have you got ISTA? It comes with instructions for most jobs and there might be a BMW procedure for testing it.

The low and high side pumps are expensive, so we need to fire the right part(s) at it!

I do have ISTA. What diagnostics should I run through it?
Low side pump is cheap enough and easy to replace... I will start there and wait for advice on ISTA.

[barf]

Intank pump is PWM controlled by ECU according to load and other parameters.

[wings516]

Update. Installed a new fuel pressure rail sensor and the car still runs like crap. Actually, worse.
Cranking seems like it is about to die, and almost doesn't start after 10-15 cranks. Idle continues to be very rough. The car now drives like it has 1 horsepower until it hits about 1800-2000 rpm and then it gains full power.

Threw my hands up and brought it to the dealer. Tech told me the issue all along was the fuel pressure sensor. He was seeing 164 bar at the sensor with the car off, and no residual pressure in the rail (meaning the regulator is fine?). Wiring and reference voltage was good.

Cost to replace another fuel pressure sensor I just spent $200 and 30 minutes of time myself? $1200

I'm kind of at a loss here. Looking for some advice. What are the odds I got a bad Bosch sensor? He didn't say if he took cranking/idle pressures, which I feel like would be good info to have to investigate the hpfp?

[dieselwagon]

Damn, that sucks. Sorry.

Its not helpful I know, but in the past with other diesels, I have had a lot of luck with using additives to the fuel to 'clean' injectors and things. Much of them are snake oil, but some of the more reputable brands do something. It might be worth seeing if you can keep the car running and try something that cleans out the fuel system a little.

As for sensors - I had an ongoing issue that I couldnt track down - fingers crossed I have fixed it and it seems to be working well. Tried a bunch of things but turned out that it was the MAF sensor was failing. Replaced a couple of other sensors including the MAP. Not suggesting to throw parts at it (never a good idea), but it might be worth digging through to see what might be affecting it.

Did you try ISTA? I find it one of the worst systems to use as its unfriendly, but when you get to the tests, its pretty thorough when completing them. What I have failed to do is find out where the real-time data is, so I use Bimmerlink for that. Its not perfect, but does give some decent data.

[wings516]

Thank you. I have scoured ISTA and everything keeps throwing lean codes in bank 1 and pressure being too low. Cleaned the MAF with no changes. What were you experiencing with your MAF dying? I have also been using hot shots additives over some time to address that point.

[Eddamoo]

Can you give a full list of your current codes? The information so far is quite disjointed.

If you're getting Lean codes, your EGR could be stuck open for example.

[wings516]

Originally Posted by Eddamoo

Can you give a full list of your current codes? The information so far is quite disjointed.

If you're getting Lean codes, your EGR could be stuck open for example.

These were taken shortly after the first replacement of the sensor.

I think you were just using the EGR as an example, but that has been coded to be off per tuner. The level sensors/ride height errors are normal; I retro'd Xenons in place of the halogens.

I unfortunately do not have the ISTA readout where it was showing the lean codes, but I have uploaded the codes from my generic code reader as well.

[MinivanDan]

Did you happen to code your injectors when you put the new ones in?

[wings516]

Originally Posted by MinivanDan

Did you happen to code your injectors when you put the new ones in?

Yes.