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CarDoc, Auto Mechanic
Category: Car
Satisfied Customers: 519
Experience:  IMI L3 Motor Vehicle Mechanic
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Engine is stalling when i decelerate Assistant: Is the check

Customer Question

Engine is stalling when i decelerate
Assistant: Is the check engine light on? Does the car stall at idle or when driving?
Customer: When i driving the check engine is appear for a second and when is disapeared the car is running again
Assistant: What is the make/model/year of your car?
Customer: Bmw e90 318i 2006 n46 engine
Assistant: Are you fixing your 318i yourself? What have you tried so far?
Customer: Yes, i changed the valvetronic i cleaned the throttle body
Assistant: Anything else you want the Mechanic to know before I connect you?
Customer: I have no errors in dashboard the check engine light it appear only when the car is stalling and the handbrake with yellow and control traction is appearing in dashboard
Submitted: 6 months ago.
Category: Car
Expert:  Marc Webster replied 6 months ago.

Hello my names Marc, ill assist you with this problem, let me take a look at the notes above

Expert:  Marc Webster replied 6 months ago.

is the fault happening all the time, and do you have a way to disable the traction control on your vehicle via a button

Expert:  Marc Webster replied 6 months ago.

should be a DTC button somewhere on the dash, press and hold this for 8 - 10 seconds, the light will stay on permamnantly this indicates the traction control is now disabled, do not drive the car yet. let me know when you have got to this stage.

Customer: replied 6 months ago.
Ive got in this stage
Expert:  Marc Webster replied 6 months ago.

take the car for a spin, be very caerfeul as the traction control is now disabled, the yellow light should remain on the dashboard permamnently. if the fault dissapears then i think i may know what it is. let me know after a road test and be very careful round corners

Customer: replied 6 months ago.
The problem still persist the check engine came out for a sec the car stall and back to normal just now i had already traction control off but the yellow hand break didn't came out
Expert:  Marc Webster replied 6 months ago.

ok, this can rule out a problem on the traction control system that can limit the performance and make it judder, so we rule that out
my next advice would be to check the mass air flow sensor have you done this already?

Customer: replied 6 months ago.
I unpluged the mass air flow and i was driving with it like that and still was the problem, thing is if i plug and odb2 reader the voltage is 0
Expert:  Marc Webster replied 6 months ago.

the voltage to what is 0 ?

Customer: replied 6 months ago.
To the mass air flow bank 1
Expert:  Marc Webster replied 6 months ago.

ok, this could indicate a fault in the wiring , and would explain the symptoms, the mass air flow helps control the fuel air mix, and if unplugged should resort to stored values to run smooth. with a reading of 0v this would indicate a break in the wire somewhere and being totaly unresponsive, my advice would be to check all the wiring for the mass air flow sensor, and replace the sensor aswell

Customer: replied 6 months ago.
I was checked the wire conection 3 times and the fuses for valvetronic and everithing is ok with it. Can be a problem with the fuel pump? Or valvetronic not to have the setting right ?
Expert:  Marc Webster replied 6 months ago.

im unable to assist any further im not certain about the valvetronic issue, would you like me to leave this for another expert.

Customer: replied 6 months ago.
No is ok thank you anyway
Expert:  CarDoc replied 6 months ago.

Thank you for using JA. I'm Baz, one of the automotive experts, I try to be available in the afternoon on weekdays and in the evenings on the weekend. I apologise if I do not respond to your question promptly, I can assure you that I will respond as soon as I can. Thank you

What type of fault code reader did you use? Generic obd2 readers don't pick up faults on BMW cars.

Do you have power+ground at the MAF connector?

Customer: replied 6 months ago.
Hi , i was lookin if i have some wires disconnected and i found my ecu have water inside it. Can you advise what to do please if it can be repaired or i need a new one and if the car will be ok after i repair/replace it.
Expert:  CarDoc replied 6 months ago.

If you're doing the work yourself, I would recommend opening it and dry it out and clean the pcb+components with an electrical contact cleaner and see what happens after. Leave it on a radiator for a few days because water can get under the black chips on the pcb even if it all looks dry, use compressed air if you have access to it.

There are online services that repair ECU modules (which is the best option), because if you replace the ECU, you may have to replace other components such as the BCM/igntion module+keys etc.