N54 Hesitant Power

grahams · 08-28-2020, 06:01 AM

Hi All,

I'm hoping there is someone who's had this issue before and can point me in the right direction.

I have been struggling with my n54 since buying it a couple of years ago and in short I'm getting pretty tired of it being bad to drive.

Since my ownership the car has has new turbos, eldor coils and 1 step colder plugs gapped to 20 thou, intake valves cleaned and a high pressure fuel pump
Modifications: catless downpipes, MHD stage 2 98ron, charge pipe.

For clarity the car has been like this without the mods too, they have just accentuated it.

When applying partial throttle you're never quite sure how much power you're going to get. Put your foot down a bit and it starts to do something and then with maybe 0.5-1s delay power kicks in much harder. When cornering this is a nightmare as feeding in the power gradually is almost impossible. The car also seems to run on a bit when you close the throttle. Let off and there is a delay.

I have started to think this could be a fault BOV but there are also a lot of sensors deciding how the car is run so not wanting to jump in without knowledge I thought it best to ask here first.

On WOT the car runs fine bar some timing being pulled up high. The issue is when you apply partial throttle or are transitioning from partial to WOT. I trust the car operates almost solely on open loop during WOT.

When the car had a JB4 on it I used to get very very bad bad boost oscillations when on partial throttle. The car would suddenly surge in power and let off again as the PID struggled to manage the boost levels, even extreme duty cycle changes didn't change this. I removed the JB4 because of this but think there is an underlying issue.

I don't frequent the forums for the BMW much as I'm sure like a lot of others find there are countless posts saying "have you got warranty" and for someone with a strong technical knowledge this just doesn't cut the mustard. I'm hoping there will be technical folk out there who can shed light on this issue.

Thanks

Graham

iqraceworks · 08-28-2020, 08:27 AM

Have you tried resetting the throttle adaptations? Have you tried running logs to see what your throttle is doing in relation to your gas pedal? Have you checked your vacuum like to make sure you have no leaks? Ever replaced your boost solenoids?

I would run some logs...see what's going on.

You've been dealing with this for 2 years? Wow...that stinks!

grahams · 08-28-2020, 08:48 AM

Unfortunately I have done that to no avail. The throttle does close intermittently when the boost goes over target.

Not done vacuum test and solenoids original. There are all items on the list but before buying any parts I want to have a rationale behind the purchase. I have a list of about £700 of parts which could be causing this. Quite a sum of money for a car I drive barely 1000 miles in a year.

You can't see a lot on the logs unfortunately.
https://datazap.me/u/grahams/2nd3rd-...og=0&data=3-18

RoughKnight · 08-28-2020, 09:29 AM

if throttle is closing its cause DME thinks your overboosting, find the leak

stewbets · 08-28-2020, 10:45 AM

Have you tried the linear throttle setting in MHD to see if that helps? It definitely sounds like a deeper issue, but I'm curious if that feels better. Your .5 to 1 second delay in power sounds normal to me for a turbo, at least at lower RPMs. So you're running a BOV? Does it give you a nice woosh when you let off the throttle or does it flutter a bit? If it's wooshing, I'd say it's not the problem.

The most curious thing to me about your description is when you said "The car also seems to run on a bit when you close the throttle. Let off and there is a delay." Do you mean that the car still pulls for a moment after lifting off the pedal? That would be very concerning to me!

grahams · 08-28-2020, 10:45 AM

Quote:

Originally Posted by RoughKnight

if throttle is closing its cause DME thinks your overboosting, find the leak

Boost or vacuum?

This portion of the log is a good example of this happening. However I think this is a different trait to the one I discuss above.

https://datazap.me/u/grahams/2nd3rd-...-21&zoom=4-140

Bimmer_Bro · 08-28-2020, 10:52 AM

Sounds like bad boost solenoids to me. They can cause very unpredictable boosting since they control the waste gates. They are pretty cheap and easy to do yourself. If they are the originals I would just do them to rule them out.
What bov are you using? And what version of MHD are you running?

Saif2018 · 08-28-2020, 10:54 AM

Quote:

Originally Posted by grahams

Unfortunately I have done that to no avail. The throttle does close intermittently when the boost goes over target.

Not done vacuum test and solenoids original. There are all items on the list but before buying any parts I want to have a rationale behind the purchase. I have a list of about £700 of parts which could be causing this. Quite a sum of money for a car I drive barely 1000 miles in a year.

You can't see a lot on the logs unfortunately.
https://datazap.me/u/grahams/2nd3rd-...og=0&data=3-18

That log is a bit all over the place. V8 maps have known issues reported by several users.

First flash V9 or v7.1 map.

Secondly Can you do a proper 3rd gear log.

Turn DSC fully off, bring the car upto 3rd gear 2500rpm, start log, go Full throttle, keep the throttle pinned let the car shift into 4th then back off.

Obviously do this in a safe place.

Bimmer_Bro · 08-28-2020, 10:58 AM

Definitely avoid version 8! It's terrible in my opinion. Version 7.1 seems to run the best for most people.

grahams · 08-28-2020, 11:10 AM

Quote:

Originally Posted by stewbets

Have you tried the linear throttle setting in MHD to see if that helps? It definitely sounds like a deeper issue, but I'm curious if that feels better. Your .5 to 1 second delay in power sounds normal to me for a turbo, at least at lower RPMs. So you're running a BOV? Does it give you a nice woosh when you let off the throttle or does it flutter a bit? If it's wooshing, I'd say it's not the problem.

The most curious thing to me about your description is when you said "The car also seems to run on a bit when you close the throttle. Let off and there is a delay." Do you mean that the car still pulls for a moment after lifting off the pedal? That would be very concerning to me!

I have that setting ticked to see if it was a map table characteristic but it isn't. Actually it made it worse. It also happens with the car on the OEM map too though.

I have the standard diverter valves. My other car is a turbo with a larger turbo for the displacement and the power delivery is instant and predictable when coming on and off the accelerator so there is something off here either mechanically or electronically. It's definitely not lag as the change is sharp and not like a smooth progression you get with boost building to target. The td03s are tiny so at 2000-3000rpm they're at full chat.

Spot on though, that's exactly what happens when you let off, there is a noticeable delay, like it's still going. Although short it is noticeable.

Other car..

Bimmer_Bro · 08-28-2020, 11:23 AM

Quote:

Originally Posted by grahams

Quote:

Originally Posted by stewbets

Have you tried the linear throttle setting in MHD to see if that helps? It definitely sounds like a deeper issue, but I'm curious if that feels better. Your .5 to 1 second delay in power sounds normal to me for a turbo, at least at lower RPMs. So you're running a BOV? Does it give you a nice woosh when you let off the throttle or does it flutter a bit? If it's wooshing, I'd say it's not the problem.

The most curious thing to me about your description is when you said "The car also seems to run on a bit when you close the throttle. Let off and there is a delay." Do you mean that the car still pulls for a moment after lifting off the pedal? That would be very concerning to me!

I have that setting ticked to see if it was a map table characteristic but it isn't. Actually it made it worse. It also happens with the car on the OEM map too though.

I have the standard diverter valves. My other car is a turbo with a larger turbo for the displacement and the power delivery is instant and predictable when coming on and off the accelerator so there is something off here either mechanically or electronically. It's definitely not lag as the change is sharp and not like a smooth progression you get with boost building to target. The td03s are tiny so at 2000-3000rpm they're at full chat.

Spot on though, that's exactly what happens when you let off, there is a noticeable delay, like it's still going. Although short it is noticeable.

Other car..

How many miles on your ride? I would still try replacing boost solenoids and inspect or replace those vacuum lines.
Also inspect those vacuum lines to your DVs. Maybe a leak on those is causing them not to vent properly.

TheN45Struggle · 08-28-2020, 11:43 AM

I just went through this situation, it seems like lag or lack of fuel but for me it was my elbow on the chargepipe that was collapsing from pressure, so verifty your elbow from the lower chargepipe to your upper charge pipe isnt collapsing

grahams · 08-28-2020, 01:38 PM

I'll get onto the better revision of MHD as a start, best to go to stage 0 so I can log but we can rule out any mapping issues.

Lots of good suggestions here. Appreciate the feedback so far.

This log is pre-downpipes and valve cleaning but does show the delay when letting off the pedal and throttle closures from over boosting.

Vacuum lines are of course the cheapest place to start so how many meters of each type (braided and non-braided) does one need to do the entire n54 as for vacuum line it's quite dear.

https://datazap.me/u/grahams/older-s...ta=2-3-4-18-21

Vinc3 · 08-28-2020, 04:30 PM

I'd suggest checking for any splits in the vacuum hoses first... How many miles have you done?

Possibly injectors?

Clean the air sensor in the chargepipe too, I just put a BMS charge pipe on mine and the sensor was covered in oil... Installed a BMS oil catch can too to prevent the air load of oil that goes through these cars!

Can you put it in a garage for a health check? Hoses, injectors etc?

I can vouch for MHD maps as I've just taken a shit stage 1 map off mine with MHD to stock, and then put the stage 1 MHD on and it's lovely. Was a version 9 map.

Bimmer_Bro · 08-28-2020, 06:21 PM

Quote:

Originally Posted by grahams

I'll get onto the better revision of MHD as a start, best to go to stage 0 so I can log but we can rule out any mapping issues.

Lots of good suggestions here. Appreciate the feedback so far.

This log is pre-downpipes and valve cleaning but does show the delay when letting off the pedal and throttle closures from over boosting.

Vacuum lines are of course the cheapest place to start so how many meters of each type (braided and non-braided) does one need to do the entire n54 as for vacuum line it's quite dear.

https://datazap.me/u/grahams/older-s...ta=2-3-4-18-21

About 12 feet will work. 3.5mm is factory size. I fine silicone best as it won't fray and it high temp resistance. I used 4mm and it also fit fine. Just do each line one at a time and it's super easy. The wastegates are the hardest part as you are going by feel.
I wonder if your DVs are not releasing the pressure once your let off causing an over boost spike.

Use a very sharp exacto knife to cut the old ones off at the nipples. The intake manifold one going to the DVs is very small and delicate. Do not break it!

Saif2018 · 08-28-2020, 06:30 PM

Quote:

Originally Posted by grahams

I'll get onto the better revision of MHD as a start, best to go to stage 0 so I can log but we can rule out any mapping issues.

Lots of good suggestions here. Appreciate the feedback so far.

This log is pre-downpipes and valve cleaning but does show the delay when letting off the pedal and throttle closures from over boosting.

Vacuum lines are of course the cheapest place to start so how many meters of each type (braided and non-braided) does one need to do the entire n54 as for vacuum line it's quite dear.

https://datazap.me/u/grahams/older-s...ta=2-3-4-18-21

You will likely get throttle closures with the stock map, I just double checked with mine, and I had it too. Seems normal to me.

I'm on v7.1 and I get some throttle closures, but in my opinion the map runs better for my car.

When I tested v9 map, I had zero throttle closures when I went WOT.

As mentioned by others, replacing all Vacuum lines is highly recommended if you haven't done so. It's cheap and can prevent boost leaks which can result from worn out ones in future.

08-28-2020, 06:01 AM	#1
grahams Enlisted Member 6 Rep 39 Posts Drives: 135i, Clio 172 Join Date: Mar 2020 Location: London iTrader: (0)	N54 Hesitant Power - Unpredictable throttle Hi All, I'm hoping there is someone who's had this issue before and can point me in the right direction. I have been struggling with my n54 since buying it a couple of years ago and in short I'm getting pretty tired of it being bad to drive. Since my ownership the car has has new turbos, eldor coils and 1 step colder plugs gapped to 20 thou, intake valves cleaned and a high pressure fuel pump Modifications: catless downpipes, MHD stage 2 98ron, charge pipe. For clarity the car has been like this without the mods too, they have just accentuated it. When applying partial throttle you're never quite sure how much power you're going to get. Put your foot down a bit and it starts to do something and then with maybe 0.5-1s delay power kicks in much harder. When cornering this is a nightmare as feeding in the power gradually is almost impossible. The car also seems to run on a bit when you close the throttle. Let off and there is a delay. I have started to think this could be a fault BOV but there are also a lot of sensors deciding how the car is run so not wanting to jump in without knowledge I thought it best to ask here first. On WOT the car runs fine bar some timing being pulled up high. The issue is when you apply partial throttle or are transitioning from partial to WOT. I trust the car operates almost solely on open loop during WOT. When the car had a JB4 on it I used to get very very bad bad boost oscillations when on partial throttle. The car would suddenly surge in power and let off again as the PID struggled to manage the boost levels, even extreme duty cycle changes didn't change this. I removed the JB4 because of this but think there is an underlying issue. I don't frequent the forums for the BMW much as I'm sure like a lot of others find there are countless posts saying "have you got warranty" and for someone with a strong technical knowledge this just doesn't cut the mustard. I'm hoping there will be technical folk out there who can shed light on this issue. Thanks Graham
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08-28-2020, 08:27 AM	#2
iqraceworks Brigadier General 2098 Rep 3,811 Posts Drives: 2007 335i Join Date: Aug 2019 Location: Missouri iTrader: (0)	Have you tried resetting the throttle adaptations? Have you tried running logs to see what your throttle is doing in relation to your gas pedal? Have you checked your vacuum like to make sure you have no leaks? Ever replaced your boost solenoids? I would run some logs...see what's going on. You've been dealing with this for 2 years? Wow...that stinks!
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08-28-2020, 08:48 AM	#3
grahams Enlisted Member 6 Rep 39 Posts Drives: 135i, Clio 172 Join Date: Mar 2020 Location: London iTrader: (0)	Unfortunately I have done that to no avail. The throttle does close intermittently when the boost goes over target. Not done vacuum test and solenoids original. There are all items on the list but before buying any parts I want to have a rationale behind the purchase. I have a list of about £700 of parts which could be causing this. Quite a sum of money for a car I drive barely 1000 miles in a year. You can't see a lot on the logs unfortunately. https://datazap.me/u/grahams/2nd3rd-...og=0&data=3-18 Last edited by grahams; 08-28-2020 at 08:54 AM..
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08-28-2020, 09:29 AM	#4
RoughKnight Private First Class 54 Rep 174 Posts Drives: BMW 335xi N54 Auto Join Date: Apr 2019 Location: Ottawa Ontario iTrader: (0)	if throttle is closing its cause DME thinks your overboosting, find the leak __________________ -------------------------------------------------------- ARM CP, DP, 7.5 FMIC, TiAl Q Bov MHD Stage2+/xHP/xDelete Road to 500hp daily on the way (ya right lol) --------------------------------------------------------
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08-28-2020, 10:45 AM	#5
stewbets Captain 452 Rep 823 Posts Drives: '08 335xi, '04 545i Join Date: Sep 2019 Location: Dayton, OH iTrader: (0)	Have you tried the linear throttle setting in MHD to see if that helps? It definitely sounds like a deeper issue, but I'm curious if that feels better. Your .5 to 1 second delay in power sounds normal to me for a turbo, at least at lower RPMs. So you're running a BOV? Does it give you a nice woosh when you let off the throttle or does it flutter a bit? If it's wooshing, I'd say it's not the problem. The most curious thing to me about your description is when you said "The car also seems to run on a bit when you close the throttle. Let off and there is a delay." Do you mean that the car still pulls for a moment after lifting off the pedal? That would be very concerning to me! __________________ 2008 335xi 6MT - 16T China Turbskies - eBay FMIC, DP & CP - VRSF Inlets - SSR DCI's - Walbro 450 LPFP - RFP e85 Tune
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08-28-2020, 10:52 AM	#7
Bimmer_Bro Captain 394 Rep 972 Posts Drives: 2010 BMW 335xi LCI Join Date: Dec 2019 Location: Calgary Alberta Canada iTrader: (0)	Sounds like bad boost solenoids to me. They can cause very unpredictable boosting since they control the waste gates. They are pretty cheap and easy to do yourself. If they are the originals I would just do them to rule them out. What bov are you using? And what version of MHD are you running? __________________ Instagram : @Bimmer_bro
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08-28-2020, 10:58 AM	#9
Bimmer_Bro Captain 394 Rep 972 Posts Drives: 2010 BMW 335xi LCI Join Date: Dec 2019 Location: Calgary Alberta Canada iTrader: (0)	Definitely avoid version 8! It's terrible in my opinion. Version 7.1 seems to run the best for most people. __________________ Instagram : @Bimmer_bro
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08-28-2020, 11:43 AM	#12
TheN45Struggle New Member 0 Rep 23 Posts Drives: e92 335i Join Date: May 2015 Location: toronto iTrader: (0)	I just went through this situation, it seems like lag or lack of fuel but for me it was my elbow on the chargepipe that was collapsing from pressure, so verifty your elbow from the lower chargepipe to your upper charge pipe isnt collapsing
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08-28-2020, 01:38 PM	#13
grahams Enlisted Member 6 Rep 39 Posts Drives: 135i, Clio 172 Join Date: Mar 2020 Location: London iTrader: (0)	I'll get onto the better revision of MHD as a start, best to go to stage 0 so I can log but we can rule out any mapping issues. Lots of good suggestions here. Appreciate the feedback so far. This log is pre-downpipes and valve cleaning but does show the delay when letting off the pedal and throttle closures from over boosting. Vacuum lines are of course the cheapest place to start so how many meters of each type (braided and non-braided) does one need to do the entire n54 as for vacuum line it's quite dear. https://datazap.me/u/grahams/older-s...ta=2-3-4-18-21
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08-28-2020, 04:30 PM	#14
Vinc3 Your Clothes Are Black! 16 Rep 74 Posts Drives: 335d XDRIVE Join Date: May 2009 Location: Kent iTrader: (0)	I'd suggest checking for any splits in the vacuum hoses first... How many miles have you done? Possibly injectors? Clean the air sensor in the chargepipe too, I just put a BMS charge pipe on mine and the sensor was covered in oil... Installed a BMS oil catch can too to prevent the air load of oil that goes through these cars! Can you put it in a garage for a health check? Hoses, injectors etc? I can vouch for MHD maps as I've just taken a shit stage 1 map off mine with MHD to stock, and then put the stage 1 MHD on and it's lovely. Was a version 9 map.
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