[Tuned335i]

1.) Get a boost gauge

2.) Only a small percentage of cars are experiencing a boost spike (that we know of)

3.) A boost spike, if it does occur, isn't going to blow up your motor or transmission.

It's an issue for sure and needs to be addressed, but it's not going to kill your car. We need more data from people to compare what the PROcede logs vs. what the secondary boost gauge shows regarding spikes and max boost numbers...

[scalbert]

Originally Posted by Orb

You did mention that the problem was repeatable at 3000 RPM right were the maximum amount of torque is produced so I assuming boost as well?

No, not always repeatable. That makes this all more interesting and enjoyable to diagnose.

[scalbert]

Originally Posted by Orb

This did make me think that if there was a very minor leak the ECU may be adapting to it and overshooting under certain conditions so if this was the case then it may be possible that a mechanical device (diverter valve) is not responding predictably at certain boost levels.

The issue I find with a leak is that I do not see how it would cause a spike. The wastegate actuators are vacuum operated and default to open. So the DME (or PROcede) has to try and keep them closed otherwise no boost is made. A leak in the vacuum lines shoulc cause the system to build boost more slowly or not at all. My boost builds very quickly; too quick I suppose.

[scalbert]

Originally Posted by Tuned335i

1.) Get a boost gauge

2.) Only a small percentage of cars are experiencing a boost spike (that we know of)

3.) A boost spike, if it does occur, isn't going to blow up your motor or transmission.

It's an issue for sure and needs to be addressed, but it's not going to kill your car. We need more data from people to compare what the PROcede logs vs. what the secondary boost gauge shows regarding spikes and max boost numbers...

+10

This is not a critical flaw causing us to borderline on impending driveline failure. It should be resolved but can be managed in the mean time. Heck, I rarely go WOT, so I can manage when I do and the manner of which I do this.

I too would like others to perform this same exact test to see if they can induce the spike. But I suspect the majority do not have an external boost gauige to compare with.

[e.n335]

I did not read all the postings, just one short question. Is it possible that the diverter valves are undersized now and cannot blow off fast enough ? When I accelerate @ WOT, the steptronic shifts at e.g. 13 psi, after the shift I have lower revs and 14+ psi. I did not see this with v1.47.

Thanks,
Eugen

[scalbert]

Originally Posted by e.n335

I did not read all the postings, just one short question. Is it possible that the diverter valves are undersized now and cannot blow off fast enough ? When I accelerate @ WOT, the steptronic shifts at e.g. 13 psi, after the shift I have lower revs and 14+ psi. I did not see this with v1.47.

Thanks,
Eugen

That would be unrelated to the spike. The diverters are only active (open) when there is manifold vacuum.

[e.n335]

Originally Posted by scalbert

That would be unrelated to the spike. The diverters are only active (open) when there is manifold vacuum.

Thanks for your answer. Even when it's unrelated to the discussed spike, what could be the cause for the behavior I described ?

[scalbert]

Originally Posted by e.n335

Thanks for your answer. Even when it's unrelated to the discussed spike, what could be the cause for the behavior I described ?

It may be in the way it is responding and could be a slight spike. Does it hang on at 14.5 or does it drop?

[e.n335]

It hangs on for 1-2 seconds, then it drops.

[e.n335]

For all of you V2 owners who want to play it save I have tested torque settings which do not exceed 15 psi, in any case, until the boost issues are solved:



I use these settings by myself now. Yes, you feel the power decrease.

- Eugen

[E90 335i]

My guess is that the V2 owners without a boost gauge are thinking they are okay because of what the logging software is reporting to them. The slight few that have a boost gauge and took the time to notice it are seeing the boost spikes. My guess is that the more V2 users that get a boost gauge will start seeing the spike. This seems isolated to only three people because only these people have bothered to put a boost gauge in and monitor it.

[e.n335]

I have a boost gauge, the torque settings are tested by monitoring the gauge.

- Eugen

[E90 335i]

Eugen,

I know you have a boost gauge and that is my point. You and the other two guys on here who are having these spike issues did the actual testing with gauges, not the logging software PROcede has. I'm sure since you guys have gauges and did the testing, you noticed the spikes. I bet if all the V2 users did the same, we'd have a vast majority of users with the same symptoms. It seems to be isolated only to the people who have boost gauges -- I hope I am wrong, but it sure seems that way. Best of luck finding a resolution.

[Orb]

Originally Posted by scalbert

The issue I find with a leak is that I do not see how it would cause a spike. The wastegate actuators are vacuum operated and default to open. So the DME (or PROcede) has to try and keep them closed otherwise no boost is made. A leak in the vacuum lines shoulc cause the system to build boost more slowly or not at all. My boost builds very quickly; too quick I suppose.

I agree with you that this not likely and the leak would have to be extremely small and all the other pieces have to fall in place. I only mentioned this as Shiv did have a customer who had spiking problems with v2 which was caused by a small leak at the diverter valve tubing connection. I hope Shiv can explain this one.

Orb

[DrDomer]

Originally Posted by scalbert

The issue I find with a leak is that I do not see how it would cause a spike. The wastegate actuators are vacuum operated and default to open. So the DME (or PROcede) has to try and keep them closed otherwise no boost is made. A leak in the vacuum lines shoulc cause the system to build boost more slowly or not at all. My boost builds very quickly; too quick I suppose.

In the idle phase the wastegates default to closed. At least that's what the documentation at the top of the Forced Induction forum says. Technically if the wastegates are closed then all exhaust gases go to the turbine of the turbocharger to build boost (makes sense - less turbo lag). The solenoids actuate the wastegates to open them to bleed exhaust gases and prevent overboost.

[Sniz]

subscribed......good work guys, hope you get it resolved w/ Vishnu's help tomorrow.

[Tuned335i]

I assume everyone with a boost gauge has it installed in the same place, i.e., in the diverter valve (the BMW documentation calls them blow off valves). Is there any way that the spikes in boost could be just what is seen inside the intake piping between the intercooler and the throttle plate because the spring loaded diverter valves are not reacting fast enough, possibly due to the fact that we're running +6-7psi more than a stock engine?

Eugen mentioned this a few posts ago and after reading the documentation section on Blow-off Control, and it sounds like that could be a contributing factor...

If this is true, then the engine itself isn't seeing the boost spike, but it's spiking in the intake plumbing and at the intake turbine itself which apparently is exactly what the diverter/blow-off valves are supposed to prevent.

Someone who knows about this stuff needs to chime in...

[Moggie]

Originally Posted by E90 335i

Eugen,

I know you have a boost gauge and that is my point. You and the other two guys on here who are having these spike issues did the actual testing with gauges, not the logging software PROcede has. I'm sure since you guys have gauges and did the testing, you noticed the spikes. I bet if all the V2 users did the same, we'd have a vast majority of users with the same symptoms. It seems to be isolated only to the people who have boost gauges -- I hope I am wrong, but it sure seems that way. Best of luck finding a resolution.

I've yet to verify that the PROcede data logging does not see the spike but since my symptoms otherwise match those of Scalbert so I expect that data logs are going to look good. My laptop is almost back to working so I should have this data by Monday. BTW I am reading the boost from a tee place close to the divertor values. I'm assume that this is where everybody is taking their readings from?

[Orb]

Originally Posted by Tuned335i

I assume everyone with a boost gauge has it installed in the same place, i.e., in the diverter valve (the BMW documentation calls them blow off valves). Is there any way that the spikes in boost could be just what is seen inside the intake piping between the intercooler and the throttle plate because the spring loaded diverter valves are not reacting fast enough, possibly due to the fact that we're running +6-7psi more than a stock engine?

Eugen mentioned this a few posts ago and after reading the documentation section on Blow-off Control, and it sounds like that could be a contributing factor...

If this is true, then the engine itself isn't seeing the boost spike, but it's spiking in the intake plumbing and at the intake turbine itself which apparently is exactly what the diverter/blow-off valves are supposed to prevent.

Someone who knows about this stuff needs to chime in...

Good question…I would like to know how it all being instrumented as well.

The diaphragm valve by its design is fast reacting. The problem with this valve is they are not typically designed for differential pressure more than 10-12 PSI. At higher pressure the valve can start to work unexpectedly due to fluttering or seating and resetting problems and could cause a momentary restriction or even leak after resetting. The behavior can be very inconstant and hard to repeat. It is not very clear if the valve is designed to work at this pressure or if Shiv has even validated this. I don’t think the plumping would cause enough of restriction to be of any concern.

It doesn’t look like this is a problem but I wouldn’t rule it out. Too many pieces are missing to get a clear picture.

I think Shiv will need to chime in to clarify all our assumptions.

Orb

[e.n335]

Originally Posted by Moggie

I've yet to verify that the PROcede data logging does not see the spike but since my symptoms otherwise match those of Scalbert so I expect that data logs are going to look good. My laptop is almost back to working so I should have this data by Monday. BTW I am reading the boost from a tee place close to the divertor values. I'm assume that this is where everybody is taking their readings from?

Yes, the boost reading source is correct. Close to the diverter valves. I am getting there up to -24 inHg. I aviod to test the high boost peaks (18+ psi ) you get. Shiv should do. Anyway, I get boost peaks where there should be none ( WOT, right after shifting, steptronic ).

- Eugen

[Moggie]

FWIW here are a couple of data logs I just recorded.
During the two bursts on the first log I recorded 17.4 and 16.8 on my boost gauge. I estimated the location of the 17.4 with the red dotted line. You can see that the log is only reporting about 14.5 psi max.


The second log was when I was trying to provoke a spike by suddenly letting off the gas. Here data log records those very short spikes but my external boost gauge did not.

One other data point. Under very light cruise conditions the data log showed a 0.5 - 0.8 psi boost whilst I was not seeing any boost at all. I don't know what all this means -- I'm just reporting my findings (v2.0.1 default map).

[Sniz]

My guess is that this is hardware related, not software.....I think you are on the right track.