[Yozh]

Here trying to help someone who is having this issues. The person has gone through quite a lot of indepth research, diagnosis and logging. The reason I help is because of language limitations of the vehicle owner. Thought this may be interesting to those that race their cars at the limit of a drag strip. Lots of little things may stack up at the limit and who knows, some may experience the same.

A bit of a background on the car. E90 335d US Spec, imported into one of the Eurasian countries. Car had been inspected for CBU. Found some CBU, about 1-2mm on the walls of swirl ports, about 10-15% restriction. Intake manifold cleaned as well as top of the swirl ports. Swirl flaps are still in place, but will be removed shortly. No pics of the CBU. Car had been deleted with a downpipe, factory gutted SCR. EGR and EGR cooler had been deleted. All necessary sensors in place. The DDE has been retuned, but not through any of the known tunes we know (JR, BPC, DUDMD, Malone). It is some Euro adapted tune. Also, originally, when the vehicle was purchased it had a limp mode and was not in a driveable state. Owner spent several days diagnosing it and found issues with fuelling system. Pressure contol valve and flow control valve were replaced. Pressure control valve was replaced by previous owners and was from a 530d. Car would drive fine after flow control valve replacement, but would throw a code until correct pressure control valve was fitted.

I have suggested to the owner that MAF adaptations should be cleared because of a new MAF and Mean Quantity adaptations should be done at the same time. Given the fact that fuelling system was updated as well with new sensors, the following adaptations should also be done: mean quantity, rail pressure sensor, increment wheel (due to CBU work).

Owner experiences the above codes at higher boost pressures and higher speeds. The logs that will be presented later, you will see that basically from about 80kph/55mph, owner hits pedal to a metal and does not let go. At about 180kph/110mph error sets in and if pedal is not relaxed a limp mode will set it. Otherwise, the vehicle performs fine.

It should be noted that MAF, MAP, One pressure converter and all the vacuum lines had been replaced. Pressure converters has been swapped places and there is no change in behaviour. Owner had followed a suggested process for testing physical vacuum actuators for all three turbo control sets, wategate, turbo switchover and compressor bypass. All seem to be functioning and holding vacuum. System vacuum was tested in-drive situation and in conditions that fault is experienced at. Vacuum is held throughout a high boost pull. Same was tested for all three sets of turbo control systems. videos are presented later below.

Here are the fault descriptions:

Attachment 1755039

Attachment 1755040

Attachment 1755041

Here is a view of a TestO log that shows pedal value, RPM and Speed. You can see that from third gear, throttle was engaged 100%. Subsequent view will be of the same log, but with different set of values shown. It also worth noting that a series of logs were provided basically repeating the conditions and fault issue at hand, and they are all very similar.

Attachment 1755054

As soon as pedal hits the metal, turbo switchover releases vacuum and switches completely to the LP turbo. Blue line. This is a normal behaviour. This also will make a compressor bypass fully open. They go hand in hand. Compressor bypass parameter was not logged, but it's a standard behaviour. Will see later in video.

Attachment 1755057

One thing to keep in mind when comparing graphs of similar values in TestO. Visually, they may not line up, but based on actual values, they actually may be bang on. For example, a value of actual and expected air mass. Same values, visually, may be different, but values may be very closely aligned. Here is a graph of Air Mass expected vs actual against RPM. Please ignore the data past 14th second as this is where the problem is. But is also interesting to note that air mass drops right before the shift. Is is MAF being saturated? Anyone else had seen this behaviour at a full fuel run?

Attachment 1755058

Here is rail pressure actual vs expected. Values are very closely aligned. But it's interesting to note that actual is very jumpy and a strange behaviour at shiftpoints. I think it's all in the adaptations that need to be performed. May be an injector? Again, please ignore anything past 14th second.

Attachment 1755059

14th Second Problem Too bad TestO chose yellow for actual value of boost graph colour. But basically, it reaches 3299mbar (47.8 absolute/33.1 gauge) pressure and then a perfect linear drop and then back up.

Attachment 1755060

Here is the same against an expected boost. They go hand in hand with actual being about 4 psi higher throughout. NOte that drop in actual happens first, then actual. Same goes for other parameters such as airmass and rail pressure. Boost pulls down first, everything else folows, naturally.

Attachment 1755061

Here is Boost vs Exhaust Pressure. Throughout this pull, ration stayed within 1.3/1.4 to boost and that is normal. What is interesting, is the EMP bump right after boost dropped.

Attachment 1755062

You can see the same in this video. It shows boost readout through TestO and a vacuum gauge hooked to wastegate. You can see that boost reading drops to atm value and then steady back up, like in our TestO logs. Vacuum on wastegate first builds as wastegate opens and then when boost drops, wategate vacuum is rapidly removed that results in wastegate closure that creates our EMP bump. When Boost is back online, wategate comes online as well
And here is vacuum at wastegate that shows wastegate opens and then drops closed. And the drama of this has been shown in the first video against boost.


Next steps:
-owner will reset adaptations
-owner will swap boost sensors to see if the problem persists (current boost sensor is new)

I feel that this is where the problem is. It is very unusual for boost reading to drop in such a linear fashion and out of sync with voltage readout. I feel that somewhere there is an electrical fault. Owner has verified wiring all the way to the DDE to make sure no shorts or breaks. I feel that boost pulls everything else after it, it's a trigger for the behaviour. May be it's a tolerance stack up somewhere and adaptations will help. If this persists, I can only think that somewhere in the tune something is not right and some protection is activated.

Would love to hear expert thoughts on the above. And sorry for the long one.

[Yozh]

reserved

[Yozh]

Dmitriy from DUDMD Tuning posted a great response. Just linking here for continuity.

https://m.facebook.com/groups/188773..._comment_reply

[Specail_K]

So im having the same issue as described above....but for the life of me cannot find the reply from Dmitriy.

Any help would be appreciated!

[Yozh]

What tune do you have?

[Specail_K]

Originally Posted by Yozh

What tune do you have?

Malone 2.9

[Yozh]

Contact Malone. They had the same issue a while ago but fixed it. It was an overboost protection.

[Figo]

Hi all, I have exactly the same problem. Can I have the solution please...
I can't find the answer from Dmitriy and Malone...

[Yozh]

Dmitriy’s answer is in the link above.

[Figo]

Originally Posted by Yozh

Dmitriy’s answer is in the link above.

Thanks Yozh to your answer, but the Facebook link doesn't work...

[Yozh]

It works if you are a part of that group. But basically it’s an overboost issue where map sensor gets maxed out with a tune. If these codes are present they will throw you into a limp. What tune do you have. Usually, it’s a tune issue.

[Figo]

Originally Posted by Yozh

It works if you are a part of that group. But basically it’s an overboost issue where map sensor gets maxed out with a tune. If these codes are present they will throw you into a limp. What tune do you have. Usually, it’s a tune issue.

Thanks, i'm in the group

I bought my bmw e90 lci 335d USA broken down with stage 2 (bad tune)
After the purchase:
- 2 pressure converters remplaced (the vacuum lines are good)
- MAP Sensor replaced
- swirl flap removed (32cm plug)
- EGR removed with the Bimmertune kit
- New tune stage 2.5 (a local company)

The big turbo does not launch and after 3000 very pout and mode a limp activated

This failure known in the U.S., do you know the solution?

In addition, I think the problem comes from tune or the downpipe because there is 1 pipe for the exhaust pressure and this one is clogged (welded) and the differential pressure sensor is not present.
Normally on the bmw e9x 335d US must be 2 pipes for this differential pressure sensor

What do you think?

[Yozh]

First order is to make sure your vacuum system is all functioning correctly. Sounds like you have already replaced some items. Then, your downpipe should not have any exhaust sensor feed tubes If your car has been tuned. What tune are you running.