[rpmaddict]

Hi. I run a BMW in the United States Touring Car Championship. We are defending our national title from last year, heading into round 2 this weekend. We switched from a Corvette to a BMW with an N54 this year and are struggling to get her working. I believe our team, collectively has read over 150 posts on forums regarding underboost and our problem is not like anything we have read or seen, therefore the new thread.

First: We are FBO with 100% brand new turbo related parts and have tried custom tunes from the best in the industry, and also have MHD OTS to fall back on. We have a JB4 but have not used it.

The car is a full race build so no emissions are in place. We are using NEW OEM style Pure stage 1 turbos with enlarged inlets.

Symptom: Car revs very slowly with zero boost.

Confirmed PROBLEM: Our wastegates are not keeping the flaps closed under acceleration. They are closed at idle. We have videos of actuator arm slowly opening upon first interaction with throttle, thus bleeding off boost. When we eventually hit about 4500rpm, then the arm will close the flap in an instant and boost kicks in. This is a very slow gain of RPM from 2000-4500. Slower than if it was completely N/A. We have tried a brand new DME with no fix.

We have replaced the following parts with NEW:

Pure stage 1 turbos
LPFP
HPFP
Fuel lines
Boost Solenoids (x2 Pierburg)
All vaccum lines
Knock sensors
Vanos sensors
Tial Spring (tried 3 rates)
TMAP (2.5 and 3.5 BAR tried)
Fuel Sensor
MAP
Throttle Body - NEW (tried 3 in total)
Pedal
Vacuum canisters
PCV
All FMIC, CP, in/outlets and related hoses NEW

DIOGNOSTICS: We have run all the normal tests several times. Vacuum is perfect. Boost-leak test shows a very very small leak at the cold intake side of the Pure Turbo aluminum housing where the clamp is, but this is not affecting pressurizing the system (not a boost leak problem as we have a zero value of boost during operation). We have verified (video) the Tial BOV is operating correctly. We can manually close the wastegates at 5in using mitivac and the diaphragm holds the rod and flapper closed indefinitely, so everything post boost solenoids is okay. We replaced 3 sets of boost solenoids and it did not improve. We checked the wired DME connections for the wastegate control and they are in-tact.

CODES:

2A12 (Evap and emissions not relevant)
2A13
2A18
2AFE
2F7B
However, the following codes come and go. we can usually can clear them but may reappear:
30CF Wastegate , activation
3100 Boost Pressure Control, deactivation

We did experience a 2CF9/2CFA, 2D09 but were fine after adaptation reset.

What we believe is happening and would like help to confirm:

The throttle body is not opening the valve/throttle plate. The DME will not send signal to boost solenoids because of this. Scanner proves the pedal position is working normal but the value for the throttle plate is not reacting as it should, thus the DME demands no boost.

What is the fix?

Thank you to the community in advance!

[CarAbuser]

2A12, 2A13 and 2A18 are all DTML. You can just disable that in the tune, I don't have time to check if they cause any limp conditions but it's doubtful.

2AFE is an O2 sensor failure. I'd get that one fixed, check live data and work out which sensor is reading bad. The exact error information for that code is "NOx sensor OBDII diagnosis - Signal gain"

2F7B is oil pressure switch. Check wiring and change it, pretty easy as it's on the oil filter housing up front. This shouldn't cause limp mode.

3100 is a symptom and the cause of your issues. This is caused by 30CF which is a fault condition of the driver for wastegate 1.
The three triggers for that code are: short circuit to 12v, short circuit to ground and "Open load".

It's possible to disable the wastegate diagnostic routine that causes 30CF in the tune. It's probably better to fix it though as I suspect that boost solenoid is not going to be driving the wastegate at all. I'd test the wiring to both boost solenoids. That error combined with the oil pressure sensor is suspicious to me, I believe those 2 connectors go through the same loom.

[RSL]

We have a JB4 but have not used it.

If this means it's installed and just on map 0, consider pulling it out. Just because it's not actively being used doesn't mean it isn't there.

[rpmaddict]

Originally Posted by CarAbuser

2A12, 2A13 and 2A18 are all DTML. You can just disable that in the tune, I don't have time to check if they cause any limp conditions but it's doubtful.

2AFE is an O2 sensor failure. I'd get that one fixed, check live data and work out which sensor is reading bad. The exact error information for that code is "NOx sensor OBDII diagnosis - Signal gain"

2F7B is oil pressure switch. Check wiring and change it, pretty easy as it's on the oil filter housing up front. This shouldn't cause limp mode.

3100 is a symptom and the cause of your issues. This is caused by 30CF which is a fault condition of the driver for wastegate 1.
The three triggers for that code are: short circuit to 12v, short circuit to ground and "Open load".

It's possible to disable the wastegate diagnostic routine that causes 30CF in the tune. It's probably better to fix it though as I suspect that boost solenoid is not going to be driving the wastegate at all. I'd test the wiring to both boost solenoids. That error combined with the oil pressure sensor is suspicious to me, I believe those 2 connectors go through the same loom.

First, THANK YOU for your response. We had to race without turbo power today as we did not discover this post until this afternoon. Needless to say, things did not go well today.

Second, I mistakenly indicated a 2AFE code when, in fact it was 2EFE (fan activation). Again, nothing we are too concerned with. Once we reset the DME, the 3100 and 30CF has remained absent with new code pulls. However, it was a consistent fault for a couple weeks and we are going to tear into the wiring this week to check your recommendations.

Finally, we did learn something today. We noticed that, while there is absolutely no boost in 1st-3rd gears, once we hit 5000RPM in 4th, the boost kicks in and we are able to hold that wastegate shut with an upshift to 5th. It didn't do us much good in the turns but it may help paint the picture.

I should mention that this has been getting progressively worse. We first noticed that the turbos were shut down between 1200 and 3700 RPM in 3rd gear pulls on the dyno. As we have been trying to grab some data from our pulls, we note that the turbos would kick in at 4400, then not until 4800 and today, not until 5000RPM and only in the gears mentioned above.

our codes remain the same on the following:

2A12 DMTL
2A13 DMTL
2A18 DMTL
2EFE Fan

The 2F7B Oil pressure switch remains a constant
Today, the only new code was a CDA8 for the instrument cluster.

We are not getting CEL's or the half CEL's yet NO BOOST in 1st -3rd gears. We believe the wastegate arms are consistently opening for whatever unknown reasons. We must figure that out. Why no codes for this limp mode?

As for the JB4, the vendor sent the wrong REV unit and we've not been able to connect, so we are leaving it off until we figure out this issue.

Again, any assistance or direction would be greatly appreciated.

[CarAbuser]

Originally Posted by rpmaddict

First, THANK YOU for your response. We had to race without turbo power today as we did not discover this post until this afternoon. Needless to say, things did not go well today.

Second, I mistakenly indicated a 2AFE code when, in fact it was 2EFE (fan activation). Again, nothing we are too concerned with. Once we reset the DME, the 3100 and 30CF has remained absent with new code pulls. However, it was a consistent fault for a couple weeks and we are going to tear into the wiring this week to check your recommendations.

Finally, we did learn something today. We noticed that, while there is absolutely no boost in 1st-3rd gears, once we hit 5000RPM in 4th, the boost kicks in and we are able to hold that wastegate shut with an upshift to 5th. It didn't do us much good in the turns but it may help paint the picture.

I should mention that this has been getting progressively worse. We first noticed that the turbos were shut down between 1200 and 3700 RPM in 3rd gear pulls on the dyno. As we have been trying to grab some data from our pulls, we note that the turbos would kick in at 4400, then not until 4800 and today, not until 5000RPM and only in the gears mentioned above.

our codes remain the same on the following:

2A12 DMTL
2A13 DMTL
2A18 DMTL
2EFE Fan

The 2F7B Oil pressure switch remains a constant
Today, the only new code was a CDA8 for the instrument cluster.

We are not getting CEL's or the half CEL's yet NO BOOST in 1st -3rd gears. We believe the wastegate arms are consistently opening for whatever unknown reasons. We must figure that out. Why no codes for this limp mode?

As for the JB4, the vendor sent the wrong REV unit and we've not been able to connect, so we are leaving it off until we figure out this issue.

Again, any assistance or direction would be greatly appreciated.

2EFE will cause your problems. Your cooling fan needs fixing. The engine is going to stay in emergency mode until you sort that. If you have removed the fan for a good reason then it's possible to bypass this check in the tune.

I would send the JB4 back to the supplier and get a refund, it's not useful. If a JB4 has been installed at any point it's worth checking the connectors in the DME box as it's possible some pins got bent or damaged by the install.

[rpmaddict]

Originally Posted by CarAbuser

2EFE will cause your problems. Your cooling fan needs fixing. The engine is going to stay in emergency mode until you sort that. If you have removed the fan for a good reason then it's possible to bypass this check in the tune.

I would send the JB4 back to the supplier and get a refund, it's not useful. If a JB4 has been installed at any point it's worth checking the connectors in the DME box as it's possible some pins got bent or damaged by the install.

Thanks for responding.

We disconnected the EOM fan and have a high flow custom race unit. I believe it was this way when we had our first race with the new setup and things were okay. I could be wrong. You are suggesting that the 2EFE will cause limp mode immediately, regardless that water temps are at 200 degrees or less?

Believe me we tried sending the JB4 back. The vendor sent us to the manufacture and they have not offered a solution. It was never successfully connected to the vehicle. We were sent the incorrect BT connector and it simply has never been powered up at the app. Could the fact that the pins were connected cause an issue, though connectivity has never been established? That would be a mind screw.

[CarAbuser]

Originally Posted by rpmaddict

Thanks for responding.

We disconnected the EOM fan and have a high flow custom race unit. I believe it was this way when we had our first race with the new setup and things were okay. I could be wrong. You are suggesting that the 2EFE will cause limp mode immediately, regardless that water temps are at 200 degrees or less?

Believe me we tried sending the JB4 back. The vendor sent us to the manufacture and they have not offered a solution. It was never successfully connected to the vehicle. We were sent the incorrect BT connector and it simply has never been powered up at the app. Could the fact that the pins were connected cause an issue, though connectivity has never been established? That would be a mind screw.

It's just possible that one of the pins was bent when installing the JB4. Something to check however improbable.

The high flow custom race fan is probably the cause of the issue. Having a bad stock fan causes those exact issues regardless of temp. It's a safety feature. Try plugging the stock fan back in, clear the faults then go for a test drive.

If you can confirm the fan is the cause of the problems you'll have to just get the electric fan diagnostic tuned out. It'll be monitoring the circuit so any aftermarket fan will cause that error.

[feuer]

Originally Posted by CarAbuser

2EFE will cause your problems. Your cooling fan needs fixing. The engine is going to stay in emergency mode until you sort that. If you have removed the fan for a good reason then it's possible to bypass this check in the tune.

I would send the JB4 back to the supplier and get a refund, it's not useful. If a JB4 has been installed at any point it's worth checking the connectors in the DME box as it's possible some pins got bent or damaged by the install.

JB4 is great. I been tracking my n54 car since 2010. Won’t consider doing on the track without it.

[Cloverdale]

A read of a JB4 log by staff at Burger or forum member may have determined your issue by now.

[rpmaddict]

Originally Posted by Cloverdale

A read of a JB4 log by staff at Burger or forum member may have determined your issue by now.

That would be good if we had a way to run the car, given it is a race car and we reside in California. It would be an instant impound situation if caught. Ask me how I know. Same as our custom tuner, we cannot even get him an MHD log unless we A: get on-track B: get into boost.

[rpmaddict]

Originally Posted by CarAbuser

It's just possible that one of the pins was bent when installing the JB4. Something to check however improbable.

The high flow custom race fan is probably the cause of the issue. Having a bad stock fan causes those exact issues regardless of temp. It's a safety feature. Try plugging the stock fan back in, clear the faults then go for a test drive.

If you can confirm the fan is the cause of the problems you'll have to just get the electric fan diagnostic tuned out. It'll be monitoring the circuit so any aftermarket fan will cause that error.

Our tuner created a new version that moved the 2EFE to a shadow inactive code. We are still experiencing the problem. HOWEVER, we are also getting the oil switch plausibility code since we bypass our oil signal to a stand-alone in-car guage. Can code 2F7B cause an engine power interruption as well, CarAbuser?

[IllSic_Design]

Originally Posted by rpmaddict

Our tuner created a new version that moved the 2EFE to a shadow inactive code. We are still experiencing the problem. HOWEVER, we are also getting the oil switch plausibility code since we bypass our oil signal to a stand-alone in-car guage. Can code 2F7B cause an engine power interruption as well, CarAbuser?

I would assume so. These cars use damn near every sensor to gauge how the engine is running, if one doesn't communicate it usually puts the car into limp mode as a safeguard

Is this a reputable BMW/N54 tuner, because he should know all this?

[CarAbuser]

Originally Posted by rpmaddict

Our tuner created a new version that moved the 2EFE to a shadow inactive code. We are still experiencing the problem. HOWEVER, we are also getting the oil switch plausibility code since we bypass our oil signal to a stand-alone in-car guage. Can code 2F7B cause an engine power interruption as well, CarAbuser?

Disabling the code doesn't stop the diagnostic, it just hides the dashboard light. The error codes are just a warning, the tuner either needs to disable fan diagnostic or alter the parameters so that the electrical profile of the new fan doesn't fail the check.

[rpmaddict]

Originally Posted by IllSic_Design

I would assume so. These cars use damn near every sensor to gauge how the engine is running, if one doesn't communicate it usually puts the car into limp mode as a safeguard

Is this a reputable BMW/N54 tuner, because he should know all this?

I think so. He is well known in all forums. I'll bring up the shadow situation brought up below.

[rpmaddict]

Originally Posted by CarAbuser

Disabling the code doesn't stop the diagnostic, it just hides the dashboard light. The error codes are just a warning, the tuner either needs to disable fan diagnostic or alter the parameters so that the electrical profile of the new fan doesn't fail the check.

Makes sense (to a corvette LS guy). I'll get with the tuner and see what he says. I appreciate the on-going assistance.