[Tunafish]

2012 E93 N55 Auto, FMIC updated, Elder coil, ngk 97506 all from FCP. I am having throttle closures. Not sure if it's an issue with the car or tune.. I have read that most say it might be the boost solenoid but I got a new from FCP (Pierburg 1174762635) a coupe months back with no change. The car has been doing the throttle closures since stock.. Here's the data:

Stock
https://datazap.me/u/tunafish389/sto...og=0&data=4-15

Stock with new FMIC
https://datazap.me/u/tunafish389/new...og=0&data=4-21

Stage 1 91ACN
https://datazap.me/u/tunafish389/91-...og=0&data=4-21

Stage 1 93OCT
https://datazap.me/u/tunafish389/log...og=0&data=4-21

Thanks for the feed back.

[e90_flyer]

I'm positive this is what blew my charge pipe today. Throttle reduction on the on ramp caused boost build up and POP! MHD Stage 1+ 2011 e90 N55

I think it's actually pretty common in turbo cars when searching the internet? Essentially the engine protecting its self from a harmful situation. This of course causes momentary massive pressure build up in the charge section of the car. I think as long as your charge pipe section can handle it, it's not really an issue. Unless you are feeling shuddering and an actual performance loss.

This article is referring to Ford Eco-Boost engines, but I think the general engineering principles are the same.

http://stratifiedauto.com/blog/ecobo...-closures-bad/

[e90_flyer]

It probably shouldn't be like that though, but I will say this happens to me as well. I'm far from an expert just putting that out there, look up some info on other turbo cars and you might be able to glean more info.

[e90_flyer]

What I see is that your boost target/load target is going above what it wants, and the throttle dials back to protect the engine from over boost pressure that could cause problems with combustion (detonation/knock)

I think the answer we need is what causes the boost/load to go above target?

Is it improper waste gate action, improper MAF/MAP sensor information, ???

[TheGoodTheBadTheUgly]

Originally Posted by e90_flyer

I'm positive this is what blew my charge pipe today. Throttle reduction on the on ramp caused boost build up and POP! MHD Stage 1+ 2011 e90 N55

I think it's actually pretty common in turbo cars when searching the internet? Essentially the engine protecting its self from a harmful situation. This of course causes momentary massive pressure build up in the charge section of the car. I think as long as your charge pipe section can handle it, it's not really an issue. Unless you are feeling shuddering and an actual performance loss.

This article is referring to Ford Eco-Boost engines, but I think the general engineering principles are the same.

http://stratifiedauto.com/blog/ecobo...-closures-bad/

Trust me it is an issue since you have a mixture that has a higher pressurized air content which might cause detonation as you mentionned, if timing is not tuned accordingly.

I initialy tought i had overboost between gear shifts because of throttle closure but it also happens in the middle of a pull when actual load meets requested load leading to more closure.

I can't seem to find a solution for it, so I am guessing that its because or the OTS tunes. I figuredthat a custom tune would probably fix this or I hope...

https://datazap.me/u/thegoodthebadth...og=0&data=4-21

[Tunafish]

Yeah i am thinking custom tune but not sure if that will help.. I think that its normal for the n55 but not sure.. It would be nice to know if it is an issue before trying custom tune..

[carguy138]

Had a similar issue and tracked it back to fuel quality.

Try running the tank low, put in several gallons of 100+ octane race gas and re-log.

Not sure if it was related to the covid shut downs but even top tier gas was terrible a few months ago. So bad that I was getting similar closures and timing corrections on the 91 ACN map while running Shell 93.

[Tunafish]

I understand if we were getting timing corrections but what we have should not cause throttle closure.. I think it more related to boost/torque targets meet.. I dont know if its one or the other because they both happen at the same time as throttle closures..
My thinking is that torque uses boost numbers as part of its calculation and when throttle closes it makes boost levels "thinks" its going up which in turn makes car thinks there is more torque than actually is.. The throttle closes to keep torque at target. But this false boost is actually not letting the cars run at top torque targets.. I am sure someone in the more know will correct me..

Either way i suspect that the car would run stronger without the throttle closers and suspect not to see an overboost..

[TheGoodTheBadTheUgly]

Originally Posted by Tunafish

I understand if we were getting timing corrections but what we have should not cause throttle closure.. I think it more related to boost/torque targets meet.. I dont know if its one or the other because they both happen at the same time as throttle closures..
My thinking is that torque uses boost numbers as part of its calculation and when throttle closes it makes boost levels "thinks" its going up which in turn makes car thinks there is more torque than actually is.. The throttle closes to keep torque at target. But this false boost is actually not letting the cars run at top torque targets.. I am sure someone in the more know will correct me..

Either way i suspect that the car would run stronger without the throttle closers and suspect not to see an overboost..

I don't quite believe that it is fake boost because when I am reaching these high psi values the car will sometime cutout/shake as if it was misfiring since the fuel injection can't keep up with the highly pressurized air mixture.

I don't know how to quite explain it but its more violent than a regular misfire and it happens when my boost peaks.

[Tunafish]

You sure the cut outnot throttle closure? That usaully coincides with peak boost..

[TheGoodTheBadTheUgly]

Originally Posted by Tunafish

You sure the cut outnot throttle closure? That usaully coincides with peak boost..

Ill try to log and notice the moment where it happens. It could be due to the high throttle closure, but I would expect it to happen more often. Never happens around 23 psi but at much higher values of 25-28 psi.

[TheGoodTheBadTheUgly]

Originally Posted by Padiyah

wassup guys.. this is my first time here and i need some help asap.. i bought me a 3series because i heard they were easy to work on.. so my car cranks but doesnt start. so long story short i found out its my valvetronic motor has to do with it.. or atleast the code says..valvetronic system : no movement identified.. so my question is. do i need to drain all my engine oil when im about to open my valve cover to remove my valvetronic.

Hey, you should move your question to a separate thread or under a post that adresses this issue if you want people to look at your issue and actually help you.

The current thread focuses on overboosting and peopme won't adress your issue here and might even get anal. For your own good I suggest you create a thread with your issue.

Best of luck!

[TheGoodTheBadTheUgly]

Originally Posted by Tunafish

You sure the cut outnot throttle closure? That usaully coincides with peak boost..

Can you try to explain ehat you mean by fake boost I don't see how it can be fake boost or I guess I don't get the concept you are trying to explain.

Our cars are over boosting and when the throttle plate closes the pressurized air is trapped in the chargepipe and the pressure goes up even more. The reading of the TMAP takes into account the absolute pressure of the air so I don't see how it can be faked. The only thing that could potentially affect the reading is hot intake air temperature because it would transfer heat to the silicone membrane which will have a thermal expansion. The instant the throttle plate will open, that pressurize air will be intaked in the cylinders.

Now when the throttle plate opens, the air can expand in the intake manifold and have a pressure drop before entering the cylinders but I don't know if this even relevant considering the fact that the air is being displaced so fast.

Finally another point leading me to believe that the pressure readings we are seeing are not falsed is the fact that my ETS charge pipe disconnected a few times and that one of my meth plugs was even ejected.

[Tunafish]

The fake is just as you describe. We are getting a PSI reading before the throttle body. Once the throttle body starts to close it starts to make an orifice. This will lose PSI on the down stream side of the orifice... I am not sure if the car compensate for this variance or even how big this variance is but there are formulas to calculate the difference of measured pressure and actual going into the cylinders.. Beyond me..

I imagine that these pressure are a big variance from one another because you don't see the major overboost (fake) without the throttle closers for what I have seen.. This is why I say "fake" because the pressure going into the cylinders is not the same as being measured. The bigger the throttle closer the bigger the variance.

[TheGoodTheBadTheUgly]

Originally Posted by Tunafish

The fake is just as you describe. We are getting a PSI reading before the throttle body. Once the throttle body starts to close it starts to make an orifice. This will lose PSI on the down stream side of the orifice... I am not sure if the car compensate for this variance or even how big this variance is but there are formulas to calculate the difference of measured pressure and actual going into the cylinders.. Beyond me..

I imagine that these pressure are a big variance from one another because you don't see the major overboost (fake) without the throttle closers for what I have seen.. This is why I say "fake" because the pressure going into the cylinders is not the same as being measured. The bigger the throttle closer the bigger the variance.

Yeah I guess its a shot in the dark trying to imagine what happens in there. Best thing to do would be to take approximate measure of a intake manifold, make a CAD file out of it and modelize it with Star CCM+ or other CFD program.

Do you think there is a way to utilise the TMAP in intake manifold to read pressure values?

[Tunafish]

Looking into this a little more, i believe the charge pipe and intake pressure sensors are the same for n55 after about 3/2011 production dates to ~2013 (PWG). So we should be able to view this data.. I will have to see if i can see it with Protool.

[Tunafish]

So I able to log intake manifold pressure with Protool.. There names and data are kinda raw. To sum it up the throttle closure does reduce intake manifold pressure and increase charge pipe pressure by a two psi difference at peak... The intake manifold pressure is still over boosting target.. You might notice different number on log than below because the PSI is including ambient pressure which was 12.4psi.. So 12.4psi will be zero boost in datalog.

Peak boost pressure set point (target)17.6psi
Charge pipe boost (pressure in front of throttle) 19.9psi
Intake manifold absolute pressure measured 17.9 psi
Throttle angle relative to lower stop (throttle position) 38.8%

Before throttle closure
Target 16.4psi
Charge pipe 16.7psi
Intake manifold16.5psi
Throttle 99.9%

After throttle closure
Target 14.2psi
Charge pipe 12.6psi
Intake manifold 12.5psi
Throttle 99.9%

https://datazap.me/u/tunafish389/log...7-9&zoom=32-48

This wasn't a full pull but enough to see the throttle closure, weather wasn't the best..