Slight hesitations under full load

fmorelli

Major General
Staff member
Aug 11, 2017
3,177
2,905
0
54
Virginia
www.morelliguitars.com
Ride
E89 Z4 35i, F10 535d
I've been having an issue for some time now. My car went through a slew of upgrades which I thought might address the issue, so I didn't worry about it too much. My car is a 2011 Z4 N54 30k miles, FBO/inlet/outlet, stock turbos. Under full acceleration (say mash the pedal at 2k) the car builds boost and RPM but hesitates like 100 milliseconds for every second, as if you went to 60% throttle momentarily then back to 100%. From 2k to 6k it will do it 4-5 times on the climb. The car doesn't jerk or anything, not that strong. There are no codes. Vacuum lines look like new. The car makes full boost no issues. Runs like a freight train aside from this funky hesitation.

I'm thinking I have a hardware issue. It was doing it on my 93 pump gas tune. Then I did Index 12s, BL coils, 95770 @ 0.028", LPFP Stage 2, fuel lines, 02 pre-cat sensors, and went to flex fuel. Completely new tune, obviously. It does the same exact thing from E10 to E75. Hence my suspicion that it is hardware. Here's a typical log: https://datazap.me/u/fmorelli/july-1-2018-ff-v1?log=0&data=3-20

@NoQuarter suggested I check out the boost solenoids and wastegates. Before I go checking things (and figure out how to test), I thought I'd pop out to the bigger group and see if there is any advice on tests, other ideas, experiences, et cetera.

Thanks, Filippo
 
Last edited:

Jeffman

Captain
Jan 7, 2017
1,472
528
0
07B4F9A6-43EC-4F7F-8FF8-E58B1C17A7EC.png
Filippo,

Your boost control is oscillating (my guess is your tune WGDC is too aggressive). But to rule out the tune I’d flash back to stock, or if you’d rather not go into your DME and switch your FF plugs to OE plugs, flash a FF tune that uses the same WGDC control tables as stock.
 
  • Informative
Reactions: fmorelli

Rob09msport

Major
Oct 28, 2017
1,928
661
0
Monroe CT
Ride
09 335i msport le mans 18 x5
I was gonna say same sounds like throttle closure. Quick ghetto test block off your air filters halfway that will show that it deff your wastegate duty cycle or something that can be fixed with tune
 

Jeffman

Captain
Jan 7, 2017
1,472
528
0
I was gonna say same sounds like throttle closure. Quick ghetto test block off your air filters halfway that will show that it deff your wastegate duty cycle or something that can be fixed with tune
Throttle log looks solid, however.
 

Rob09msport

Major
Oct 28, 2017
1,928
661
0
Monroe CT
Ride
09 335i msport le mans 18 x5
Is it gear dependant and does long pressing traction control alter behavior at all. And last question are your front and rear overall tire diameters close if diff by how much?
 

fmorelli

Major General
Staff member
Aug 11, 2017
3,177
2,905
0
54
Virginia
www.morelliguitars.com
Ride
E89 Z4 35i, F10 535d
No difference in gears, though my logs are all 3rd gear pulls. I haven't tried long push on the DSC ... will do and report back. 1.2% difference between my front and rear tires. I just got done running the zero turn around and cutting all this grass. Planning to wash the sleds and do the vacuum test on the N54. Will report back. Thanks guys ...

Filippo
 
Last edited:

fmorelli

Major General
Staff member
Aug 11, 2017
3,177
2,905
0
54
Virginia
www.morelliguitars.com
Ride
E89 Z4 35i, F10 535d
So I tested the boost solenoids by pulling the inlet line from the vac canister for each. I drew 25 inches of vacuum. The front solenoid bled down to 10 inches over about 45 seconds, and pretty much didn't want to bleed much more. The rear solenoid bled down to 10 inches in about 10 seconds, and was happy to continue bleeding down. Reading around forums, I can't get a bead on what this means - I've seen different answers with bleed down varying between solenoids seeming common.

Hopefully someone hear can say intelligent things? Thanks in advance!

Filippo
 
  • Like
Reactions: Rob09msport

fmorelli

Major General
Staff member
Aug 11, 2017
3,177
2,905
0
54
Virginia
www.morelliguitars.com
Ride
E89 Z4 35i, F10 535d
So aside from my boost solenoid test questions above, I got back out and did another set of pulls. Prior post was for Sport+ without DSC off (since @Rob09msport asked about DSC off). Here's the pull with Sport+ / DSC Off. Here's the prior pull (same everything but only Sport+). Jeffman posted the first (prior) log, so I've attached the latest here for those that doesn't want to go to datazap.

Filippo

Screen Shot 2018-07-08 at 7.07.25 PM.png
 

Rob09msport

Major
Oct 28, 2017
1,928
661
0
Monroe CT
Ride
09 335i msport le mans 18 x5
Not sure about the readings but i do know when mine were going it sounded like i had a little gremlin In engine bay at idle for like 5 to 10 sec randomly but around min between cycles. Also i do believe you can bypass vacuum canisters and also try running one pressure converter at a time as that used to be a common mod with early jb tunes
 
  • Like
Reactions: fmorelli

matreyia

Major
Apr 19, 2017
1,748
685
0
Ride
335i e93
So aside from my boost solenoid test questions above, I got back out and did another set of pulls. Prior post was for Sport+ without DSC off (since @Rob09msport asked about DSC off). Here's the pull with Sport+ / DSC Off. Here's the prior pull (same everything but only Sport+). Jeffman posted the first (prior) log, so I've attached the latest here for those that doesn't want to go to datazap.

Filippo

View attachment 13231


Give this a try: Take off the coils, double check the torque on all the spark plugs, then make sure all the BL coils are seated when you reinstall them.

Ask me how I came to this advice about the torquing... yeah, same problem with all fully upgraded 'everything', no leaks.... After double checking the plug torque values, runs totally normal no matter what I do with the pedal. Those plugs apparently get loose for some reason...they literally screwed right off with barely any effort with my bare hands and the extension socket without a wrench.
 

NoQuarter

Major
Nov 24, 2017
1,545
962
0
Indiana, USA
Ride
Z4 35is, 535xi, X5 35i
Give this a try: Take off the coils, double check the torque on all the spark plugs, then make sure all the BL coils are seated when you reinstall them.

Ask me how I came to this advice about the torquing... yeah, same problem with all fully upgraded 'everything', no leaks.... After double checking the plug torque values, runs totally normal no matter what I do with the pedal. Those plugs apparently get loose for some reason...they literally screwed right off with barely any effort with my bare hands and the extension socket without a wrench.

I have had this problem as well. My fear of over torqing the plugs caused other problems. I finally bought a small enough torque wrench that I trusted.
 

fmorelli

Major General
Staff member
Aug 11, 2017
3,177
2,905
0
54
Virginia
www.morelliguitars.com
Ride
E89 Z4 35i, F10 535d
Interesting. We used a torque wrench on the install. Also, I was seeing this issue before I changed to the BL ignition system. I don't think this is our issue, given those factors.

Filippo
 

matreyia

Major
Apr 19, 2017
1,748
685
0
Ride
335i e93
Interesting. We used a torque wrench on the install. Also, I was seeing this issue before I changed to the BL ignition system. I don't think this is our issue, given those factors.

Filippo

Trust me, I am OCD about torque values. The plugs just loosened over time.
 
  • Like
Reactions: fmorelli

matreyia

Major
Apr 19, 2017
1,748
685
0
Ride
335i e93
Interesting. We used a torque wrench on the install. Also, I was seeing this issue before I changed to the BL ignition system. I don't think this is our issue, given those factors.

Filippo
I just did another double check, this time with two different torque wrenches and the plugs did get a tiny bit loose again. It didn't matter if the engine was hot or cold when torquing.

But I doubt that was my issue. The WOT oscillation is returning again. I now am suspecting the BL coils are acting up. The connectors literally crumbled from my fingers touching them when I go to check the plugs. I guess I should contact Alex to see if he can send me the updated ones for shipping costs...these coil harness things are less than a year old. I would think his warranty would cover at least the same duration as PR coils.
 

matreyia

Major
Apr 19, 2017
1,748
685
0
Ride
335i e93
sounds like you have the same issue as I do. Car pulls, but WOT on freeway... will shift then pull back, then go back to full power, and sometimes will oscillate waowaowao. Just replaced both solenoids with bmw new ones less than two months, new crankshaft sensor, camshaft sensors, stage 3 Precision Raceworks LPFP installed by Rob himself, new plugs, BL coils, you name, I got it... aluminum outlet from PSP.

Just ordered from FCP - remanufactured HPFP, new HPF Sensor, LPF Sensor. Should arrive in two weeks. Will see if all those make it go away.
 

fmorelli

Major General
Staff member
Aug 11, 2017
3,177
2,905
0
54
Virginia
www.morelliguitars.com
Ride
E89 Z4 35i, F10 535d
I had this before BL coils. Here is a log with new Eldor coils, NGK 95770s set on 0.020" gap, FBO/inlet/outlet stock turbos, 93 pump gas. https://datazap.me/u/fmorelli/october-15-2017-v14?log=0&data=3-22-29

See the WGDC Bank 1 % oscillate? As we know it mimics the PID value + adders. In my case ... it is not the BL coils, even though I have them now.

The BL coils crumble at the sleeve. This will have no bearing on what you are seeing. Assemble the connectors and put a couple wraps of black electrical tape. If you want BL to update your harness, you can do that, but I don't think it relates to this.

Filippo
 

fmorelli

Major General
Staff member
Aug 11, 2017
3,177
2,905
0
54
Virginia
www.morelliguitars.com
Ride
E89 Z4 35i, F10 535d
Just replaced both solenoids with bmw new ones less than two months, new crankshaft sensor, camshaft sensors, stage 3 Precision Raceworks LPFP installed by Rob himself, new plugs, BL coils, you name, I got it... aluminum outlet from PSP.

Just ordered from FCP - remanufactured HPFP, new HPF Sensor, LPF Sensor. Should arrive in two weeks. Will see if all those make it go away.
Ouch ... throwing parts at it is painful.

My car runs like a raped ape. The only thing is the funny oscillation/hesitation under full WOT. The car doesn't jerk, it just gently hesitates as it builds.

Filippo
 

matreyia

Major
Apr 19, 2017
1,748
685
0
Ride
335i e93
I
Ouch ... throwing parts at it is painful.

My car runs like a raped ape. The only thing is the funny oscillation/hesitation under full WOT. The car doesn't jerk, it just gently hesitates as it builds.

Filippo

I am getting fuel related faults. that's why. Also, last HPFP I will ever buy since it's FCP. And last time I changed sensors, the car ran perfect for two straight years so I think they just go bad. And when the HPF Sensor goes bad, the HPFP runs permanently at 100%, when the LPF Sensor goes bad, you get wrong data to the other systems and it's a cascading effect that will make you confused as hell because it literally feels like all kinds of other things from vacuum leaks to coils...all due to these stupid sensors. Basically you may get a situation where the HPFP is running 100% while the LPF Sensor is telling the LPFP wrong readings and the LPFP is not sending correct fuel pressures to the 100% capacity HPFP... that would definitely cause the oscillations at WOT. A mismatch between a HPFP running at 100% capacity while the LPFP is not do the same. The fuel pressure/amount differential would in theory cause oscillations. At least that's what I can think of so far.

1. I know it isn't any of the LPFP's, they are new.
2. I know it isn't the ekpm3 that is also new.
3. I know it isn't vacuum leaks - double checked all lines, upgraded them.
4. I know it isn't solenoids or vanos units, all new.
5. all faults point to voltage too high from stage 3 pumps (sometimes shadow, sometimes active)
6. also tell tale fault "2FDB fuel high pressure nach freigabe der Einspritzung" - which literally means: fuel high pressure after injector release" <---- if the pressure is high after the injectors, then it is most likely due to a bad HPF Sensor located on the fuel rail at the end tip.
7. not the injectors...they are less than three months brand new index 12. and no fuel or oil leaks anywhere.

It was time to change the HPFP anyways...
 
  • Informative
Reactions: fmorelli