[alexjustdoit]

Hi all - got overboost condition and air mass too high today. 2013 335i - car has extensive aftermarket mods including an upgraded turbo.

Some context - car was tuned with worm clamps on all turbo hoses, no boost leak codes, year later was chasing down boost leaks and underboost conditions for a while, solution ended up being that clamps failed, put more robust pressure clamps on. Finally fixed them all - car ran well. Mechanic thought that since the car was tuned with the previous clamps, could have been leaking slightly before, and so he thought I may run into overboost after the new clamps were put on and no leaks found. Now second time (infrequent) overboost happened. Air mass too high is new.

In doing my research, I'm wondering - how does the DME determine that it is overboosting? I have a GFB boost controller that has a duty cycle setting set - but I can't imagine that this controller is telling the DME what boost to expect. I am realizing I dont really know how target boost is set. If target boost is, say 20psi, where is that 20psi expected figure coming from? Is there like a boost curve in the tune that determines it? Would overboost be triggered if my pre-throttle boost says 20psi but my target boost at the same point in time is only 13psi?

If it matters - car had all mods when it was tuned, except I recently swapped in an aftermarket GFB diverter valve for better boost retention (vents progressively rather than either full open or full close)

Theoretically, when the car was tuned, there were no boost leaks. None occurred during tuning dyno runs, and the previous owner never ran into any. It was only a year or two later that they started for me. So I'm not entirely sure what would be causing it, and I'm not sure whether I buy the tech's warning that overboost would be caused by the car being tuned while it was leaking before, because while they less reliable clamps were being used back then, no leaks were found (at least not any big enough to throw a code - can a leak be so minor that it doesnt throw a code ever?).

As an aside - I was running some logs to see if I could capture the overboost and not only could I not replicate it, but I actually ran into a drive train malfunction code that cut power and forced me to pull over / restart car: 1F0526 - DME, internal fault, safety function: Torque comparison. Thinking this may just be a tune issue but I'm wondering if it is related, or separate... And while I didnt capture the overboost DME code being triggered, I see that the pre-throttle boost is 20psi but the boost target just prio to power being cut was only 13psi (and had actually been dropping slowly)

Any help or insight would be greatly appreciated... I've been chasing boost issues with this car for ages it seems.

[thejeremyman9]

Originally Posted by alexjustdoit

Hi all - got overboost condition and air mass too high today. 2013 335i - car has extensive aftermarket mods including an upgraded turbo.

Some context - car was tuned with worm clamps on all turbo hoses, no boost leak codes, year later was chasing down boost leaks and underboost conditions for a while, solution ended up being that clamps failed, put more robust pressure clamps on. Finally fixed them all - car ran well. Mechanic thought that since the car was tuned with the previous clamps, could have been leaking slightly before, and so he thought I may run into overboost after the new clamps were put on and no leaks found. Now second time (infrequent) overboost happened. Air mass too high is new.

In doing my research, I'm wondering - how does the DME determine that it is overboosting? I have a GFB boost controller that has a duty cycle setting set - but I can't imagine that this controller is telling the DME what boost to expect. I am realizing I dont really know how target boost is set. If target boost is, say 20psi, where is that 20psi expected figure coming from? Is there like a boost curve in the tune that determines it? Would overboost be triggered if my pre-throttle boost says 20psi but my target boost at the same point in time is only 13psi?

If it matters - car had all mods when it was tuned, except I recently swapped in an aftermarket GFB diverter valve for better boost retention (vents progressively rather than either full open or full close)

Theoretically, when the car was tuned, there were no boost leaks. None occurred during tuning dyno runs, and the previous owner never ran into any. It was only a year or two later that they started for me. So I'm not entirely sure what would be causing it, and I'm not sure whether I buy the tech's warning that overboost would be caused by the car being tuned while it was leaking before, because while they less reliable clamps were being used back then, no leaks were found (at least not any big enough to throw a code - can a leak be so minor that it doesnt throw a code ever?).

As an aside - I was running some logs to see if I could capture the overboost and not only could I not replicate it, but I actually ran into a drive train malfunction code that cut power and forced me to pull over / restart car: 1F0526 - DME, internal fault, safety function: Torque comparison. Thinking this may just be a tune issue but I'm wondering if it is related, or separate... And while I didnt capture the overboost DME code being triggered, I see that the pre-throttle boost is 20psi but the boost target just prio to power being cut was only 13psi (and had actually been dropping slowly)

Any help or insight would be greatly appreciated... I've been chasing boost issues with this car for ages it seems.

Good background, but where's your datalogs? Based on your sig you have a BM3 tune, so the boost target should be set in the tune. I am not really sure where the GFB boost controller is supposed to come in... are you saying you (or the tuner) set the boost target in the GFB rather that in the DME tune?

How you are tuning is going to influence the answer to most of the questions you are asking but your setup/tune seems a bit strange, at least from how you described it. If the GFB has a WGDC setting and you set that with a boost leak, then fixed the boost leak, then yes you are going to be overboosting.

How your BM3 tune is configured is also going to determine your overboosting threshold but its not clear to me how that is interacting with the GFB settings. The OEM tune is load-based and the boost target is calculated based on a load target but BM3 does not use that tuning strategy and it sounds like your car does not either. BM3 also typically allows some degree of overboost (1-3 psi) but if you exceed that is closes the throttle. The boost target is set in the DME. If its a load based tune the DME calculates the target curve, if its a boost-based tune the target is set directly. And you don't look at pre-throttle boost, you need to look at MAP (manifold boost sensor).

The GFB DV could also be a factor if your OEM DV was bleeding boost, then you fixed that "boost leak" so now your WGDC setting is too high, causing overboost.

And it is very common to have a boost leak and not throw a code so it is entirely possible.

[alexjustdoit]

Originally Posted by thejeremyman9

Good background, but where's your datalogs? Based on your sig you have a BM3 tune, so the boost target should be set in the tune. I am not really sure where the GFB boost controller is supposed to come in... are you saying you (or the tuner) set the boost target in the GFB rather that in the DME tune?

How you are tuning is going to influence the answer to most of the questions you are asking but your setup/tune seems a bit strange, at least from how you described it. If the GFB has a WGDC setting and you set that with a boost leak, then fixed the boost leak, then yes you are going to be overboosting.

How your BM3 tune is configured is also going to determine your overboosting threshold but its not clear to me how that is interacting with the GFB settings. The OEM tune is load-based and the boost target is calculated based on a load target but BM3 does not use that tuning strategy and it sounds like your car does not either. BM3 also typically allows some degree of overboost (1-3 psi) but if you exceed that is closes the throttle. The boost target is set in the DME. If its a load based tune the DME calculates the target curve, if its a boost-based tune the target is set directly. And you don't look at pre-throttle boost, you need to look at MAP (manifold boost sensor).

The GFB DV could also be a factor if your OEM DV was bleeding boost, then you fixed that "boost leak" so now your WGDC setting is too high, causing overboost.

And it is very common to have a boost leak and not throw a code so it is entirely possible.

Thanks for the reply - I didnt initially include the logs because I wasnt actually able to catch the overboost triggering during them but I can upload them either as .csv or screenshot of the graph, is one particularly better than the other? Heres a Google Drive link to some .csv's.

Im not really sure where the GFB controller comes in - I was just wondering if that changes things. The previous owner had the controller when the tune was done and the tuner advised him as to what settings to put into the controller at the same time that he gave him the tune. I dont really know how it works in regards to target boost, I just know that you set the duty cycle and it controls the boost solenoid action. I will ask GFB support how the controller might change things - they are generally very helpful.

But based on your reply... yeah, maybe there was in fact some minor boost leaking before, and now it is overshooting. So if it is a boost based tune, the boost target is statically defined by the tune it sounds, then that makes sense to me that that could be the case. Now I wonder if I just lower the duty cycle setting on the controller, if that would fix it.

I know a natural response to all this might be "just ask your tuner dummy" which I agree with, but BigBoost / Juan is incredibly hard to get ahold of. He basically does not respond to my emails. A while back I need some replacement bolts fabricated and both me and my shop were shocked that BigBoost was still in business given how they handled the whole thing, so while I've started yet another email thread with Juan, I really can't rely on him replying at all, unfortunately.

[thejeremyman9]

Originally Posted by alexjustdoit

Thanks for the reply - I didnt initially include the logs because I wasnt actually able to catch the overboost triggering during them but I can upload them either as .csv or screenshot of the graph, is one particularly better than the other? Heres a Google Drive link to some .csv's.

Im not really sure where the GFB controller comes in - I was just wondering if that changes things. The previous owner had the controller when the tune was done and the tuner advised him as to what settings to put into the controller at the same time that he gave him the tune. I dont really know how it works in regards to target boost, I just know that you set the duty cycle and it controls the boost solenoid action. I will ask GFB support how the controller might change things - they are generally very helpful.

But based on your reply... yeah, maybe there was in fact some minor boost leaking before, and now it is overshooting. So if it is a boost based tune, the boost target is statically defined by the tune it sounds, then that makes sense to me that that could be the case. Now I wonder if I just lower the duty cycle setting on the controller, if that would fix it.

I know a natural response to all this might be "just ask your tuner dummy" which I agree with, but BigBoost / Juan is incredibly hard to get ahold of. He basically does not respond to my emails. A while back I need some replacement bolts fabricated and both me and my shop were shocked that BigBoost was still in business given how they handled the whole thing, so while I've started yet another email thread with Juan, I really can't rely on him replying at all, unfortunately.

You need to upload the datalogs to datazap (free account) and post the link to the log. Just send me the link to a specific log or log that captures the issue, and a timestamp if its a huge log.

Read my thread on datalogging FYI: https://f30.bimmerpost.com/forums/sh....php?t=1732327

Knowing how the controller comes in is important. You certainly could try lowering the WGDC on the controller to see if it prevents overboost, and although i don't see a significant risk turning boost down, making any adjustments without understanding the controller functionality or how it interacts with the tune has an inherent risk.

I think i have heard similar things about BB responsiveness before...

The other question is why the GFB was added in the first place, but i am less familiar with PWG, so maybe there's a reason you can't just control WGDC with the DME...

[alexjustdoit]

Yeah, Im not really sure why the controller was added - it might be for the other controls (like being able to control how quick the boost comes in etc). Or for scenarios like this where the previous owner foresaw the need to adjust the boost without having to go back to the tuner for adjustments haha.

In talking with GFB it sounds to me like the target boost should still defined in the map in the tune and not altered by the controller, so they recommended I lower the WGDC just a tad and see if the overboost occurs, repeat until it does not. I'm thinking there was a slight boost leak when it was tuned, and that explains the very occasional overboost, so hopefully this takes care of things. This is about the easiest resolution I could hope for, so fingers crossed.

I appreciate the reply, I learned some things in this thread!

[thejeremyman9]

Let us know what happens and get some datalogs