Acceleration shutter...fuel system?

[pit1]

Hey guy,

Over the past month of so I've noticed some hesitation under heavy expressway acceleration. Most noticeable going full throttle in 6th at expressway speeds. First started as a subtle miss or "bump" from the rear end. Last night it was a noticeable shutter, skipping and vibration with a clear loss in power. This was at the tail end of a 150 mile cruise.

I feed her nothing but 93 octane and I've been through half a dozen tanks with the same result. Effects vary and are intermittent at the least. It feels exactly like the driveshaft failure of my E30, but with only 36K miles I'm suspicious it's HPFP #2 though no signs of long crank yet.

Any thoughts?

UPDATE

Confirmed HPFP issue. The dealer pulled error code (though diff this time around), opened a Puma case and reprogrammed the DME. All shutter and misses are gone, throttle response is back, and exhaust note a tad more throaty. I can be over-sensitive, but glad I'm not crazy. To confirm questions below, YES the shutter was felt between 2,200 and 2,500 RPM. Not talking about WOT scenario, just casual expressway passing. We have plenty of power down there, and the shutter was very unwelcome. However subtle misses were present here and there at even light acceleration. Symptoms were synonymous to failed oxygen sensors or bad fuel...any fuel delivery issue really.

[Mega Man]

At about what RPM are you "punching it" at?

[Cisitalia]

Mine had similar issues and my car did not exhibit the long cranks either. I did not have a check engine light, but took it to the dealer. Of course no problems at the dealer and it checked out fine. Well I knew this was just a prelude to a full blown HPFP issue and I would have to wait for it to act up again.

Well it certainly did, but it took several months later. Then one day cruising at 55 mph in fifth, I needed to pass a car and accelerated rapidly then it started to vibrate weirdly. The engine miss fired like it was running on less than six cylinders. The car also just bogged down in an extreme loss of power situation. I limped home only one mile and shut it off. Then I started it up and it ran fine at idle and when revving the engine well past 4k rpm. I backed out of the drive way and it stalled on its own. Then I got the service engine red light and it stayed locked in even after cycling on/off the car a few times. My car is a March 2009 build with only 3,800 miles on it.

I called my same SA and he said bring it in for what sounded like a HPFP problem (duh!). I had to short shift the car at low rpm gear shifts to limp it to the dealer. The engine would bog down when trying to apply any throttle more than 1/3 to ½ so I shifted at about 2500 rpm and I made it there. They had a loaner car waiting for me for a quick drop and go. This happened last week and the repair went fine and I have a couple hundred miles on it with no issues.

So your car just might be on its way to a new HPFP. Good luck.

[Dackelone]

Without the ability to scan the ECU... there is no way to know what is going on. And even then, its tough to understand some of the codes. I think, if you are a DIY-er or live far from a dealer or... are too busy(time wsie)... having a BT scanner will pay dividends! Looks like I better order mine soon. lol

[Cisitalia]

Originally Posted by Dackelone

Without the ability to scan the ECU... there is no way to know what is going on. And even then, its tough to understand some of the codes. I think, if you are a DIY-er or live far from a dealer or... are too busy(time wsie)... having a BT scanner will pay dividends! Looks like I better order mine soon. lol

I agree with Dack on this and below is a similar post that shows the benefit of a BT scanner. I was planning on getting one as well.

The OP of this post and the following post exhibit very similar problems as well as my experience.
http://www.1addicts.com/forums/showthread.php?t=390630

[randomquickness]

I don't need a scan tool to tell you, it is most likely your HPFP. Mine did the same thing for a little while until the car just died completely from HPFP failure. Read some of the many threads on it and you will find other people who had the same issue.

[nordique14]

I know that most people will say it is a precursor to a HPFP fail. I has this same thing happen to me one day when I was on a trip 300 miles from home. The car stuttered when entering a freeway. Down on power. Felt like it was not getting fuel or running on less than all cylinders. Happened again 2 more times that day after shutting down and restarting the car.

That was almost a year ago. I have not had a reoccurrence since then. Still on my first HPFP after almost 2 years. I know it will eventually fail but, for me, there seems to be a long time between the first symptoms and the eventual failure.

[adrean8j]

Still another thread of people crying wolf....a stutter on acceleration does NOT necessarily mean that it is a HPFP.....

[randomquickness]

^true, but nearly everyone I know personally who has the N54 has had similar symptoms and ended up having their HPFP fail and I know a lot of people around here with N54's. The likely hood is definitely there.

[Brad135]

Can't speak to the HPFP situation....

However, I've gotten shutter, but it was due to traction control cutting in and out on imperfect surfaces and low traction situations. Try DTC.

[adrean8j]

Originally Posted by randomquickness

^true, but nearly everyone I know personally who has the N54 has had similar symptoms and ended up having their HPFP fail and I know a lot of people around here with N54's. The likely hood is definitely there.

But saying that it IS the HPFP just drives me nuts....bottom line take it to the mechanic and have them replicate the problem...all of this forum conjecture just creates possible false diagnosis and leads to others saying "mine too!"...just sayin' I have had some stutter at acceleration in higher gears after doing long highway stints. Yet the car did not go into limp and drove normally the rest of the time...and still on my original HPFP with 32k miles on the odo....so in my opinion it could be ANYTHING.....

[RPM90]

Originally Posted by adrean8j

But saying that it IS the HPFP just drives me nuts....bottom line take it to the mechanic and have them replicate the problem...all of this forum conjecture just creates possible false diagnosis and leads to others saying "mine too!"...just sayin' I have had some stutter at acceleration in higher gears after doing long highway stints. Yet the car did not go into limp and drove normally the rest of the time...and still on my original HPFP with 32k miles on the odo....so in my opinion it could be ANYTHING.....

I concur.

We've got HPFP immanentfailiosis. It's a form of hypochondria where every problem MUST be cancer. Then, when it finally is cancer, you can say; "See, I told you it was!"

OP, there have been a number of cars with faulty injectors or coil packs.
One of these parts could easily cause the symptoms you describe.

[pit1]

Thanks for the input all. Worked out of a remote office today 75 miles down I-95, no symptoms throughout the trip today. My first HPFP failure was extremely intermittent, still not ruling that out, but agree it's not proof positive for diagnosis.

Absolutely not traction loss, stutter is most prevalent in 6th @ 2,500-3,500RPM at which point higher revs smooth things out. When it's acting up, it's subtle <3,500RPM in every gear but less noticeable under lighter drag.

Appointment next week...will follow up.

[adrean8j]

You actually try to accelerate in 6th at 2500-3500rpm??? LOL....drop that thing down a gear and see if you still have the problem...would be interesting....

[RPM90]

Originally Posted by adrean8j

You actually try to accelerate in 6th at 2500-3500rpm??? LOL....drop that thing down a gear and see if you still have the problem...would be interesting....

I agree that if you really want passing POWER then downshift.
But, I've found that at that rpm in 6th, the car moves out nicely, if you're simply wanting to accelerate at a leisure pace. It doesn't lug. This engine does have very good low rpm torque.

I could see if his rpm was under 2000rpm in top gear and he went full throttle, then there could be shudder from lugging the engine.

[BrokenVert]

Adrean and rpm90 I'm right with you guys...37k miles and no issue with my hpfp. I drive 5 hours through cell signaless mountains and I'm never afraid...just drive it until it fails, if that's what you believe the problem actually is. It's the only thig that you can do anyway

[RPM90]

Originally Posted by pit1

Thanks for the input all. Worked out of a remote office today 75 miles down I-95, no symptoms throughout the trip today. My first HPFP failure was extremely intermittent, still not ruling that out, but agree it's not proof positive for diagnosis.

Absolutely not traction loss, stutter is most prevalent in 6th @ 2,500-3,500RPM at which point higher revs smooth things out. When it's acting up, it's subtle <3,500RPM in every gear but less noticeable under lighter drag.

Appointment next week...will follow up.

Maybe Adrian might be on to something.
Are you sure engine rpm isn't lower than what you state?
If it's under 2k rpm and you floor it, it could lug the engine.
But, you'd have to be in some low rpm, probably even below 1500-1700rpm.

In top gear at low engine speed, when you go full throttle, that is quite a load on the engine. 6th is an over drive gear, not really intended for heavy acceleration.

[pit1]

Update posted top...confirmed HPFP fault. Reprogrammed DME.

[mryakanisachoad]

Originally Posted by adrean8j

Still another thread of people crying wolf....a stutter on acceleration does NOT necessarily mean that it is a HPFP.....

2 for 2 here with n54 fuel delivery issues.

335i @ 3,000 miles for HOP (high pressure pump)

and

135i @ 1,086 miles for VDO (low pressure pump)

[adrean8j]

Originally Posted by pit1

Update posted top...confirmed HPFP fault. Reprogrammed DME.

Was the HPFP replaced? When you say it is a HPFP fault that is hardware not software...the code is just the software saying there is a hardware fault. If it was just your DME being reprogrammed then the actual HPFP hardware was NOT at fault.

Originally Posted by mryakanisachoad

2 for 2 here with n54 fuel delivery issues.

335i @ 3,000 miles for HOP (high pressure pump)

and

135i @ 1,086 miles for VDO (low pressure pump)

??? And this proves what? We already know there are people with the issues at low mileage...we also know there are people with relatively high mileage without these problems...

[mryakanisachoad]

Originally Posted by adrean8j

??? And this proves what? We already know there are people with the issues at low mileage...we also know there are people with relatively high mileage without these problems...

defensive, much?

i wasn't submitting a proof, professor.

[adrean8j]

Originally Posted by mryakanisachoad

defensive, much?

i wasn't submitting a proof, professor.

No not normally padawan....but quoting me and then providing data seems to be providing proof.