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Juan Crespo
Juan Crespo, Tech Trainer
Category: BMW
Satisfied Customers: 1516
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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2006 BMW X3 3.0i i got intake monifold after i replaced with

Customer Question

2006 BMW X3 3.0i i got blown intake monifold
after i replaced with good used one its still backfiring in to intake monifold in low RPM.in higher rpm looks ok
WBXPA934X6WD32358
Submitted: 10 months ago.
Category: BMW
Customer: replied 10 months ago.
Customer: replied 10 months ago.
are you gonna get me an awensor??
Customer: replied 10 months ago.
Customer: replied 10 months ago.
COMPRESSION IN SYLINDERS IS 175+PSI
Expert:  Ron replied 10 months ago.

Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

Backfiring in most cases can be caused by either an engine vacuum leak and or a valve timing concern and in most cases the computer will set and store a fault code. Are you able to scan the computer system and see if there are any fault codes setting? Post back with the results and we can work from there.

Customer: replied 10 months ago.
before i cleared codes i had code for MAF sensor so i got good used one and nothing changedplugs were black and some wet.i replaced blown intake with good used one with all new(used) injectors.compression is good.still looking for answer.from explosion DISA valve got broken(fram that holding a door )but didnt fell a part,all still in one peace
Customer: replied 10 months ago.
Here some pictures attached below
Customer: replied 10 months ago.
Let me know
Expert:  Ron replied 10 months ago.

I would start first with replacing the Differential Intake Air Control Valve since its broken, It plays a major roll in the incoming air into the intake.

Customer: replied 10 months ago.
will take me few days to get me one
thanks keep you posted .But most important is alot of people on google discribe same problem and give me no solution!!! have you experiance this problem with bmw before?somebody must have....
Expert:  Ron replied 10 months ago.

In the cases where I have ran across the backfiring it was usually a vacuum leak and or a vale timing concern but the DIAC being broke really should be dealt with first .

Customer: replied 10 months ago.
I REPLACED DIAC VALVE AND NOTHING CHANGED.IT STILL BACKFIRES TO INTAKE IN IDLE
Expert:  Juan Crespo replied 10 months ago.

Hi there. Perhaps I can help.

Backfires are the product of lean conditions. As backfires occur, several sensors will send out signals that are out of range and the on-board computer will react by setting error codes that pertain to those signals. That means that a backfire caused by insufficient fuel pressure might result in MAF, O2 and misfire codes.

We're dealing here with a very sophiscated fuel delivery system that includes a fuel pump that has a three-phase motor, which ensures sufficient torque across the whole pump speed range. The pump speed is used to provide the required fuel pressure of 3-6 bar (43-87 psi), depending on the engine operating state.
A fuel pressure sensor sends its signal to the MSS60. The fuel pressure sensor is located behind the inner fenderwell. If the pressure sensor fails or there is a fault in the CAN bus and in the engine emergency program, the fuel pump is operated at full speed. In this process, the pressure is limited to 6 bar by the mechanical pressure sensor.
The signals from both tank fill level sensors are sent to the junction box and are forwarded to the instrument cluster via the K-CAN, where they are evaluated and displayed.

This is going to be hard to diagnose without access to ISTA software; measuring fuel pressure would confirm insufficient fuel as the cause of the backfires, but won't tell us whether it is caused by a false reading from the fuel pressure sensor, or a weak fuel pump, or bad wiring, or even a bad computer.

If you don't have ISTA, you might consider taking the vehicle somewhere where they do and can pinpoint the problem as a cheaper option to what is happening now.

Please let me know if you have any other questions.

Best Regards.

Customer: replied 10 months ago.
what steps i can take in order to pinpoint a problem?
Expert:  Juan Crespo replied 10 months ago.

Do you mean what steps using ISTA?

Customer: replied 10 months ago.
it was plug missing in intake monifold crieting huge waccum leak

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