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Matt
Matt, Mechanical Engineer
Category: BMW
Satisfied Customers: 23879
Experience:  BEng hons Mech engineering, in auto industry 22 years
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My BMW Compact 316ti year 2004 keeps cutting out I've

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My BMW Compact 316ti year 2004 keeps cutting out I've changed the Valvetronic unit I've had the air pipe at the back of the engine underneath the cover changed two sensors at the front of the engine I've put additives and cleaners into the petrol twice and started to change the petrol to BP's V8 unleaded and still get the same problem

Customer: replied 7 months ago.
I did add this at the near beginning about my BMW but have not as yet received an answer. My BMW Compact 316ti year 2004 keeps cutting out I've changed the Valvetronic unit I've had the air pipe at the back of the engine underneath the cover changed two sensors at the front of the engine I've put additives and cleaners into the petrol twice and started to change the petrol to BP's V8 unleaded and still get the same problem

Hello and welcome to Just Answer

as you're getting a fault light on then

The quickest route to repair is to have the car plugged into a diagnostic machine which will read off the fault code stored in the ECU (providing the light is still on at this point) and indicate which sensor has failed or whether the fault is more serious.

You can do a very rough and ready check yourself by unplugging sensors one at a time and seeing if any of them change the driving condition which would indicate the most recently unplugged sensor is the faulty one. This method is not foolproof though and reading a fault code off is the better method.

from your description this could be a wiring issue as things tend to expand when hot and its possible a poor or partial electrical connection is being pushed apart on one of the major sensors so check the connection plug and wiring to the following;

Airflow meter
Crank position sensor
Cam position sensor
O2 sensor
Throttle position sensor

unplug each in turn and use some switch / contact cleaner spray on the pins to ensure its all grease / dirt free

Also worth checking the connections to the fuel pump for the same reason - unplug each in turn and give them a good squirt of switch / contact cleaner - Not WD40

and also unplug and inspect the main power relays and fuses for signs of overheating or corroded terminals - so the ones for the ECU and the fuel pump

And also unplug the wiring loom connections in the engine bay one at time and inspect for corroded or recessed pins.

- Also replace the spark plugs if any of them fail this checklist:

https://www.ngksparkplugs.com/about-ngk/faqs/spark-plug-faqs/how-do-i-read-a-spark-plug

My goal is to give you the best advice that I can and I hope that I've helped today. Please remember to rate my service by selecting from the 5 stars at the top of the screen before you leave. If you need more help, use the reply box to let me know.

If you're not pleased, also let me know because rating bad does not result in a refund, there are better options. Rating now will not close this post nor prevent further replies

Thanks Matt

Customer: replied 7 months ago.
I cannot give a rating as yet because the car is not going in to the garage until Wednesday the 28th of this month. I will hand them your report and see what they say. I will though thank you for your report and hope it is of some use to them, it certainly looks useful to me. thank you

no problem

just get back to me on this post

Matt and 2 other BMW Specialists are ready to help you

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Thanks Matt