[minulache]

Hi guys,

I just installed MHD stage 1 on my N55 but it seems it doesn't meet the boost target. Is this a possible boost leak?
Everything looks alright, except the STFT and boost under target which leads me to believe that there is a boost leak but my question is, shouldn't WGDC be 100% because it should be closed to meet the boost when a boost leak occurs or it's not a rule of thumb?
Attached the log.

https://datazap.me/u/minulache/stage...og=0&data=4-16

Many thanks for the help!

[whyzee125]

Originally Posted by minulache

Hi guys,

I just installed MHD stage 1 on my N55 but it seems it doesn't meet the boost target. Is this a possible boost leak?
Everything looks alright, except the STFT and boost under target which leads me to believe that there is a boost leak but my question is, shouldn't WGDC be 100% because it should be closed to meet the boost when a boost leak occurs or it's not a rule of thumb?
Attached the log.

https://datazap.me/u/minulache/stage...og=0&data=4-16

Many thanks for the help!

I'm not super familiar with the MHD OTS maps BUT I know that Ken @ Wedge makes them. On his custom tunes at least, he uses commanded wastegate which means the boost target is all but irrelevant. That does look a little low to me but so did one of my custom tunes from him and he said that's 100% by design and he could adjust it as desired. I'm right about on target with the next revision. Could be the case here too.

[wheela]

I know Ken @ Wedge does the MHD OTS maps for n54, but I'm pretty sure Twisted Tuning does the MHD n55e OTS maps.

minulache, I don't expect you'd ever see 100% wgdc% on the n55e OTS maps. From all the n55e OTS map logs I've seen, they all seem to have a pretty big gap between boost target and actual boost, so it's hard to say. Your stft% goes pretty negative during the pull as you said, so you may be right about a boost leak, but that could also be fuel system related. Probably worth doing a boost leak test.

[minulache]

Tomorrow I am planning to do a boost leak test, just got the tools to do it today. On virtual dyno it shows similar results to stock, so it's like this stage 1 is not doing anything.

[minulache]

Tried today to smoke test but I am smoking from the inlet pipe on the turbo, so that is not the cause of the boost leak...I cannot seem to get it to pressurize so I could actually see from where it's coming from. Any ideas from where to smoke test the N55?

View post on imgur.com

View post on imgur.com

[fastboatster]

if you are smoking from the inlet pipes, that will def affect your fuel trims. That leak is downstream of MAF sensor and will absolutely affect how the car runs. you def need to replace the inlet pipe gasket

[minulache]

There is no gasket at the pipe that is joined with the inlet pipe from the turbo, the place from where I see smoke

[robrxt]

Originally Posted by minulache

There is no gasket at the pipe that is joined with the inlet pipe from the turbo, the place from where I see smoke

That plastic pipe cracked on my car near the turbo. I purchase a metal one to replace it. You can remove it and check it.

[minulache]

Tomorrow I will remove and retest on the inlet pipe on the turbo, not the one that leads to it. I also think there might be a problem there. From where did you get a metal one? The only option I could find is the VRSF but I'm not keen to get something from them

[fastboatster]

Originally Posted by minulache

There is no gasket at the pipe that is joined with the inlet pipe from the turbo, the place from where I see smoke

okay, we are talking about different spots on that pipe, I thought you were talking about the spot where it goes to the turbo.

[minulache]

Originally Posted by fastboatster

okay, we are talking about different spots on that pipe, I thought you were talking about the spot where it goes to the turbo.

Nono, sorry for the misunderstanding. Tomorrow I will test from that pipe to see if the gasket needs replacing

[wrevilo]

See this thread also. I had air leaks before and after the turbo requiring new gaskets on turbo inlet and a new pipe to the intercooler on turbo outlet.

https://www.e90post.com/forums/showt...2069688&page=2

[minulache]

wrevilo , thank you!
Did you smoke test to find out which parts you needed to replace?

[minulache]

So also the gasket that leads from the inlet pipe to the turbo is gone, tested today. Ordered the gaskets and gonna give it another try with all the new gaskets to see where the leaks lead me )

[wrevilo]

Originally Posted by minulache

wrevilo , thank you!
Did you smoke test to find out which parts you needed to replace?

Yes, the leaks were really apparent with the system smoke tested. The mechanic blocked the intake system between the exit of the air filter box and intercooler outlet pipe.

[minulache]

Update, also the gasket on the boost pressure sensor in the CP was done. Changing also that.

[Malteser_wfj]

Originally Posted by minulache

Update, also the gasket on the boost pressure sensor in the CP was done. Changing also that.

I never thought about checking this one!

I've been gettinc 2BC0 codes on and off alongside a rough idle that loves to drop below 500rpm at times & replaced the gaskets going into & out of the intercooler 17 & 19 in the diagram.

The only modification is a VRSF chargepipe.

I'll check out the sensor o-rings as well as the turbo feed pipes now.

Thanks for posting your updates

This is one of my recent-ish logs and I'll upload some more from the last week or so

https://datazap.me/u/lemansn55/30032...19&zoom=96-181

[minulache]

Update time. I replaced all the gaskets, no more leaks detected after the turbo but still same result on Stg 1: https://datazap.me/u/minulache/log-1...og=0&data=4-16

I also put Stage 1+ for curiosity on the car, and the boost seems a bit better, but still under target and negative STFT:https://datazap.me/u/minulache/log-1-2nd

Any other ideas...?

[Malteser_wfj]

Not based on any experience or data but maybe these pipes?

https://www.realoem.com/bmw/enUS/sho...diagId=11_4472

Only because I eventually want to do these myself and buy a GFB Diverter Valve the 12 year old and 120k mile factory unit

[minulache]

View post on imgur.com

Either there is something wrong with the car, or with the MHD map.
On stage 1+ only 10 whp difference (I know it's just an estimation but still...) with the boost bumped up.

[wheela]

Originally Posted by Malteser_wfj

Not based on any experience or data but maybe these pipes?

https://www.realoem.com/bmw/enUS/sho...diagId=11_4472

Only because I eventually want to do these myself and buy a GFB Diverter Valve the 12 year old and 120k mile factory unit

The boost you're achieving on 1+ seems pretty normal. That 12-ish psi you're getting at 6500rpm isn't bad for the stock turbo, I get similar on stage 2+. WGDC% is kinda high up there, but that could be due to high ambient temp (less dense air, turbo has to work harder to make boost, and needs more boost to hit load% request).

I alway suspected I had a bit of a boostleak due to stft% going negative on pulls like you. But I recently replaced my injectors and rail pressure sensor and that doesn't really happen any more.

[wheela]

Also, if you're smoke testing for leaks, there could still be some leaks that don't open up until higher pressure that you could be missing.

Did you mention what all mods are on the car?