[335i E92]

Originally Posted by DavS1

Not the same compressor surge i'm assuming he is feeling/having problems with.

Actual "compressor Surge" happens when accelerating with throtle open, Similar things happen though (turbo stalling), but under different circumstances.
This statement is describing compressor surge with throtle closed with no dump valve/stuck closed dump valve which I wouldn't class as a problem, just a noise which is the reason manufacturors fit dump valves in the first place.


325i E92, I should have asked earlier...I take it this compressor surge you describe is ON throtle, not a noise when you back off as described above?

Hi

Spot on!! The car is surging ON throtle and im NOT hearding any flutter coming off the gas!!

[335i E92]

Evening all

So here's the update!!

The car went in to my local Indy BMW specialist last week to have BMWs latest full ecu reflash. It was also suposed to have the meduim strenth yellow springs taken out of the Forge DVs and swaped for the softer green ones but they ran out of time.

So for the last week I have driven the car with a completley stanard map but with the medium yellow spring which is designed for higher boost pressue mapped cars.

Firstly the car ran much smoother with the new software but still felt a little surgy
and jerky on and off the throttle. The car had no lag, it's hard to explain but it just felt like I was riding the turbo all the time, Ide tap the throttle and I start to get an instant pull. However the pull felt contraint and strangled but constant with no boost variations.

So today Ive had the softer green springs put in and the car. The result is that it no longer feels surgy on throttle it's nice and flowy. However the boost is now all over the place. If I accelerate in 2nd full wot I get a meduim constant supply of boost up
to around 3.5rpm and then I get full boost for the rest of the rev range.

Obviously I'm hacked of, the usual 1 step forward 1 step back. I know some of you have suggsted a rolling road to look at what's going on. However given the change of spring today and the impact it's made on the drive it's obvious go me that it's a problem with the Forge DVs, springs are either too soft or too hard an I really can't be arsed dickin around with the spacers to find the best spring load. If I had know they were this fickle I wouldn't had bothered with them.

My theory is that I definatley had a fault with my oem dv's which is why I swapped for the forge and the forge dv's are clearly not working for me.

I'm thinking of ditching them and putting a set of new stock dv's on in the hope of a simple resolve with no spring tension guessing

Any help or advise would be greatly appreciated. The link that Neil supplied in the 3rd post on this thread backs up the problems I'm experiencing trying to get the correct spring resistance.

Just want to start enjoying the car again, please help

[DavS1]

Obviously, the thing to do IMO would be to fit new standard dump valves......if nothing else it eliminates them, and then the car is completely stock and such, BMW can then further investigate it as a std car and can't point the finger at anything else.

[335i E92]

Originally Posted by DavS1

Obviously, the thing to do IMO would be to fit new standard dump valves......if nothing else it eliminates them, and then the car is completely stock and such, BMW can then further investigate it as a std car and can't point the finger at anything else.

Thanks for the imput, agreed!!

I've only had them on the car for a couple of months and have had constant boost issues. I'm going to try and throw them back of Forge and demand a refund. Hopfully they'll play ball.

[doughboy]

I've yet to fit my DVs but I can't quite figure how they should cause you this much trouble? They should operate as a simple OPEN/CLOSED valve and only ever open under a closed or closing throttle, that is their function, they should never operate during acceleration or steady throttle - whatever the boost level, if the throttle is steady they should not open ever, so this means they should never effect your car under accleration or steady throttle

The DV spring is only there to hold it shut under running boost pressures, its the relative vaccum from behind the closing throttle that PULLS the DV open via the vaccum line, aided by the associated increase in boost PUSHING it open from intake tract. It should not open at any other time. If the throttle is steady then the pressures above and below the valve piston or diaphragm are equal, so the spring will hold it shut.

So DVs will not affect drive at WOT unless they are failing and leaking boost, as the OE ones are only rated to 12psi, this was the initial theory for your car.

Maybe you need to reset the engine adaptations after each change, else the DME will be chasing its tail trying to keep up? With adaptations moving the goal posts you don't know the true effect of any changes as you don't have a fixed reference point.

This is where a BT lead is handy as you can do all this yourself without visits to your indy.

[335i E92]

Originally Posted by doughboy

I've yet to fit my DVs but I can't quite figure how they should cause you this much trouble? They should operate as a simple OPEN/CLOSED valve and only ever open under a closed or closing throttle, that is their function, they should never operate during acceleration or steady throttle - whatever the boost level, if the throttle is steady they should not open ever, so this means they should never effect your car under accleration or steady throttle

The DV spring is only there to hold it shut under running boost pressures, its the relative vaccum from behind the closing throttle that PULLS the DV open via the vaccum line, aided by the associated increase in boost PUSHING it open from intake tract. It should not open at any other time. If the throttle is steady then the pressures above and below the valve piston or diaphragm are equal, so the spring will hold it shut.

So DVs will not affect drive at WOT unless they are failing and leaking boost, as the OE ones are only rated to 12psi, this was the initial theory for your car.

Maybe you need to reset the engine adaptations after each change, else the DME will be chasing its tail trying to keep up? With adaptations moving the goal posts you don't know the true effect of any changes as you don't have a fixed reference point.

This is where a BT lead is handy as you can do all this yourself without visits to your indy.

HI Mike

I really appreciate your input, unfortunately for me I’m not as technically minded as you and I can’t fully get my head around the complete operation of the DV’s above that it holds / releases boost pressure. My bad I know!!

As far as the BT cable goes, again I wouldn’t know what to look for even if I had one!!

If you look at the below link that Neil provided it discusses the issue of spring loaded DV’s and the headaches of finding the correct tension to suit the given boost pressure.

http://www.n54tech.com/forums/showth...highlight=tial

Of all the threads I’ve read about swapping DV springs none of them have mentioned having to reset the adaptations to bed in each change, I’ll check this with Mike at Woods.

Given the stark change in behaviour having had the spring swapped yesterday it obviously points to some kind of fault with them; whether this is a leak or just that the spring selection is off I don’t know.

[doughboy]

I'm no mechanic, but I'm just trying to think it through logically with a bit of physics thrown in!!!

Trying to keep it to basics, DVs should NEVER open under steady throttle or acceleration, they must only release boost on a closing throttle, so having TOO STIFF a spring should never alter WOT on-boost behaviour, only the transition phase from on-boost to off or lower boost will be altered i.e. when you close the throttle fully or partially.

TOO SOFT a spring will cause boost leaks, which can cause problems of course and effect on boost behaviour. The fact your cars WOT behaviour changed so much with the change of DVs is odd IMO, unless the softer springs are now leaking boost and causing stange behaviour.

My suggestion about resetting the adaptations has no technical basis other than the fact its seems good practice in assessing changes. As an engineer I know that any 'experiment' is useless without a known reference point on which to base your assessments.

If you reset adaptations after any change you will always be starting from the same reference point. Otherwise the DME (ECU) is changing variables you don't know about and will alter things to upset the effect of your changes.

[335i E92]

I agree with all of the above thinking logically…

All I know is when I was running the harder yellow spring with the standard map over the last week the engine felt instantly on the turbo. You could literally tap the accelerator and the turbos would pull instantly, although with this came jerky on / off throttle acceleration and the acceleration generally felt strangled.

I agreed that too softer spring will cause boost leak however I would understand that if I was getting boost that tapered of up the rev range. I’m actually getting it the other way around, on full what I’m getting what feels like 70% boost up until around 3.5rpm and then full boost after that. So it’s leaking and then closing towards the end of the pull to give boost.

[doughboy]

Hmmm.

Sounds like there's more to it than the DVs.

If Woods can reset all the adaptations for you, that should give you a benchmark.

I notice my car seems to go like stink when the adaptations are reset, its just throttle response I think, but it just seems to go great and taper off after a few days.

[335i E92]

Originally Posted by doughboy

Hmmm.

Sounds like there's more to it than the DVs.

If Woods can reset all the adaptations for you, that should give you a benchmark.

I notice my car seems to go like stink when the adaptations are reset, its just throttle response I think, but it just seems to go great and taper off after a few days.

I know exactly what you mean, I’ve had my adaptations reset a couple of times at Woods and it pulls like a train for the 1st few days n then drops off, annoying!!

I agree that it sounds more than just the DV’s, although its very odd that the variations in spring are causing such a difference.

I’m waiting for a price from Mike for a set of the oem’s.

By the way I had the AR Design catch can fitted yesterday, tidy bit of kit!!

[m1bjr]

I still dont think its the BOVS/DVS whatever you wish to call them.

My money is on a sticking wastegate still.

You need to plot the boost pressures at the manifold - the MAP pressure.
And do some full runs through the gears.
Lots of unexpected boost modulation will cause the DVs to do odd things, you may be overboosting if a gate is shut when it shouldnt be.

I think you changed out the wastegate controllers already, so then it points to the mechanical end of the turbo/actuators.
Steve

[335i E92]

Originally Posted by m1bjr

I still dont think its the BOVS/DVS whatever you wish to call them.

My money is on a sticking wastegate still.

You need to plot the boost pressures at the manifold - the MAP pressure.
And do some full runs through the gears.
Lots of unexpected boost modulation will cause the DVs to do odd things, you may be overboosting if a gate is shut when it shouldnt be.

I think you changed out the wastegate controllers already, so then it points to the mechanical end of the turbo/actuators.
Steve

Hi Steve

I agree that It doesn't make sense that symptoms I am experiencing are being caused by the DV's. There must be somthing else causing them to react the way they are to the different spring tensions.

As you said I have had the boost control solanoids changed recently and and this resulted it the car staring to pulse under wot. DMS then changed the software in their map to deliver a more progressive boost to the solanoids to stop the pulsing as they also said that they thought it was a likley to do with the way the preload had been set on the actuators when they where retrofited by BMW earlier in the year. This update did stop the pulsing but caused the car to surge and generaly just didn't feel right.

So as I mentioned earlier in this thread I've had the ecu set back to stock and I'm still having boost issues. I think the only way forward is to get it completley back to stock by taking the Forge DVs off and putting new oem dv's in.

If it still plays up then maybe some dyno diagnostics / look at the wastegates?

I drove the car earlier and was in 2nd gear 20mph i floored it and nothing for 3 seconds before the boost finally kicked in. Tried it agian and agian and it happend everytime!!

[Quisp]

I am having very simialr problems with my car. Differences would be that my car is stock except for a Dinan Stage 3 tune , oil cooler and intercooler. The similarities are surging and jerking acceleration, mild acceleration under 3500 with the full acceleratrion after 3500. Car would run strong for some time then fade after ecu flash.No codes and the dealership telling me it is in my head even though i know it is not driving like it used to. I have had both turbos and wategates replaced along with 6 injectors. but I think I am starting to hear the wastegates loosening becasue the rattle seems to be comig back.
This is my last dyno run. It shows before th dinan flash and after. Dinan saw it and said it is OK but not as good as they want,. The peak torque came on too early and there was some concern over the AFR. I am throwing these things out in case there may be something that helps yo with your situation since it is somewhat similar.
I had suspected a boost leak that wouldnt happen and would happen at higher boost pressure. I also saw mention of the possibility of a faulty sensor that would send incorrect temperature readings and then the ecu would adjust accordingly. I donot know if either of those help. I am not the most tech minded but i am smart enough to learn and this car is a learning process. I have a BT Scan tool but am not sure what values to look at in order to isolate or eliminate some of the ppossibilities. Any suggestions would be greatly appreciated. I do not mean to hijack the thread and if I did I apologize. I was thinking maybe we can help each other figure this out..

[335i E92]

Hi

Sorry to hear you having similar problems...

I'm focusing on the Forge DVs at the moment. They were surging on yellow spring although I had just had the car taken back to bone stock so this could have been the problem. After putting the green ones in the it now has serious lag if I plant my foot down I takes 2-3 seconds before I get full boost!!

Given the major effect the change of spring gave I'm taking them off and having a set of new oem dv's and adaptaions reset on Sat.

I'm hoping this will sort it, if not I'll get some dyno dyagnostics carried outto try to pin point the issue.

If it still plays up with stock DVs then I'm sure it is eiher a boost leak or a wastegate issue, maybe sticking?

What did you mean by AFR?

I'll post again at the wend with an update.

Ta

H

[m1bjr]

Air/fuel ratio.
Mixture....lean or rich.

You guys are going at this arse-about-face.
Get it to a good dyno operator.

TDI North maybe?
The southern branch is excellent and full of REAL engineers, I have been...

Some words on experience-
System-R Ltd was set-up in 2003 by Paul Jones as a Japanese Performance tuning company in the North West of England specifically for Honda vehicles.

Paul is a time served Engineer and was previously employed at Garrett Turbochargers Ltd for 11 years in various roles including Quality, Manufacturing, Mechanical engineering, New product introduction and Program management. During his 11 years at Garrett Turbochargers Paul gained a BEng (Hons), MBA and a MIEE and worked on various turbo-charger programs such as Cosworth, Focus RS, Jaguar, Bentley, Lotus, etc. as well as supporting race and competition teams at all levels including the Le Mans series, etc.

In 2004 System-R were approached by Toda Racing Europe (TDi PLC) to become their northern division in England, TDi themselves were the first company in the UK specialising in Japanese cars and offering 4 wheel drive dyno tuning.

In 2006 TDi North became accredited by the EFI University based in the USA, the EFI University is regarded as the bench mark qualification amongst tuning companies in order to obtain a thorough understanding in engine tuning

HTH matey
Steve.

[335i E92]

Hi Steve

Thanks for that amigo...

I 100% agree with your dyno dyagnostics. I just wanted to get the car back to stock 1st to rule any mods out. The stock dvs are only £80 fitted.

I live in Manchester so I'll look this guy up, does it matter that he specialises in japanese cars? Will he be able to diagnose the N54?

Thanks again for the info.

[m1bjr]

Originally Posted by 335i E92

Hi Steve

Thanks for that amigo...

I 100% agree with your dyno dyagnostics. I just wanted to get the car back to stock 1st to rule any mods out. The stock dvs are only £80 fitted.

I live in Manchester so I'll look this guy up, does it matter that he specialises in japanese cars? Will he be able to diagnose the N54?

Thanks again for the info.

I have been to the Southern outfit and its excellent.
No personal experience with the Northern but on S2ki I have heard great reports.
I thought as its not far from you, at least it'll give you a start.
A turbo car is a turbo car. All you need is a good Engineer

As for Jap specialist, it doesnt matter.
But what they will have as a result is a lot of experience with modified oem turbo systems.
The TDi South guys have worked with BMWs for endurance racing for example.

How many turbo BMW petrols are there
So this is why your average dealer mechanic will be knee deep in handbooks when you arrive. And worrying

[E92Fan]

OP - can you confirm the following status of your car, as it is now-

1) stock map or DMS remap at the moment?
2) Forge DVs or OEM DVs?
3) have the actuators been replaced, and when?
4) how were the actuators setup? were they done at a BMW dealer or at an independent?
5) have any fault codes shown themselves?


If the problems you are describing are wholly boost-related, then there is only a finite list of issues that can present themselves.

1) DVs failing - in the first instance, you changed from OEM DVs to Forge DVs to see if that would stabilise the boost variance. It appears that this hasn't worked effectively, and boost oscillation is still apparent regardless of spring choice? Does the variance still occur with OEM DVs reinstalled? This is a first course of action, because if variance does still exist then the problem does not lie with DVs.

2) Other factors that cause boost variation - Actuators, compressor failure, boost leak

The most likely cause of boost variation is a boost leak. You need to check all the boost hoses and charge pipes to see if they are all secure. You should be able to audibly hear a boost leak via a hose, as on boost the car should make a noise like a vacuum cleaner and it's hard to miss. If there is no noise, it is likely that a boost leak will be coming from a failing actuator.

Actuators are fiddly things to replace correctly - it's not good enough just to install a new actuator. The preload must be set correctly, and that requires an MIB pressure machine to measure atmospheric pressure before setting the correct preload. The wastegate diaphragm must then be regulated by hand to ensure the correct seating position. If this isn't done properly, you can very often get an underboost situation which may be minor enough to avoid causing any fault codes being stored, but major enough to cause boost oscillation.

Actuators have also been known to 'stick', due to an offset stroke causing abnormal wear to the bush. This can happen with new actuators as well. It's quite easy to see by visually inspecting the turbos - if there's a sticky residue on the actuator rod then it's likely it's failing.


Bottom line -

1) revert the car to standard
2) log boost pressure under load to see if there is any variance
3) if there is variance, then an inspection of the turbos and the turbo system is needed
4) if there is no variance, then the issue lies outside the boost control system and you will need to look at the air/fuelling system

[335i E92]

Hi Tony...

I had the dms map taken off 2 weeks ago and had the latest BMW software installed. I noticed stright away the the car had much less lag but was surging as I still had the yellow forge springs in.

I then had the softer green springs installed and i was experiencing boost leak as the spring was too soft. This is a noted problem with the new design forge dvs which I have.

Today I had a new set of oem dvs installed and the car is running perfectly!!

I think I have identified what my problem was all along. My car had the actuators replaced by a main BMW dealer in April and sincse they were fitted the car haa always felt laggy. I suspect that after having the actuators installed BMW didn't reprograme ghe software to close the wategates, I still had the software that holds thfm open slightly running on the car which wad the software fix inicially introduced to stop the metalic noise.

This I what I think has been causing my boost problems with the dms map all this time.

This has only come to light since having the latest BMW software installed a couple of weeks ago as although i have had the spring issues the car has been much less laggy and responds much much quicker.

Now with this new BMW software and standard dvs the car is running really smooth with no lag.

I'm gonna run it for a week and see how infer on then get the car mapped agian.

I hope with the standard dvs and wastegates now set to the correct closed postion I should have nailed months of boost issues!!

What's your oppionion, you agree it makes sense??

Cheers

Howard

[335i E92]

I can spell... Posting from I iPhone, fat fingers!!

[335i E92]

Hey guys... Tony? Anyone?

Any thoughts on the above theory?

[DavS1]

wastegates sitting open will cause lag/boost coming in later than normal but wouldn't affect it flat out. Metalic noise may have been wastegate penny's rattling about as they wouldnt have been held shut against the turbine.