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Steve
Steve, BMW Expert
Category: BMW
Satisfied Customers: 24191
Experience:  BMW Expert
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some times my 523i will start to chug ie forward backward while

Resolved Question:

some times my 523i will start to chug ie forward backward while driving. when i lift my foot off accelorator it stops when i put my foot down again it starts to chug again. when i stop and switch off engine, wait 10 seconds and start up and drive, the chugging has gone. the car is 1999.
Submitted: 3 years ago.
Category: BMW
Expert:  Steve replied 3 years ago.
can you please clarify what you mean by "chug" ?
Customer: replied 3 years ago.

driving along very smoothly, suddenly the car starts to shake in a forward backward jumping motion. this stops when i take my foot off accellorator and will start again if i push the accellorator. when i stop and turn the engine off, wait for 10 seconds and drive off everything is fine.

Customer: replied 3 years ago.

driving along very smoothly, suddenly the car starts to shake in a forward backward jumping motion. this stops when i take my foot off accellorator and will start again if i push the accellorator. when i stop and turn the engine off, wait for 10 seconds and drive off, everything is fine.

Expert:  Steve replied 3 years ago.

if you are driving in a forward motion, I do not understand how the car can move in a backwards motion?

 

Customer: replied 3 years ago.

the car statrs to shake and vibrate

Expert:  Steve replied 3 years ago.
do any warning lights come on?
Customer: replied 3 years ago.

no

Expert:  Steve replied 3 years ago.

this suggests a fuel delivery or mixture issue

 

common causes would be a failing fuel pump, clogged fuel filter, or bad pressure regulator

 

other things which can cause similar issues would be a failed airflow sensor or crankcase vent valve.

 

to verify the cause, you will need to replicate the issue at a time when the fuel pressure can be tested/monitored, and a diagnostic machine connected to monitor live data from all of the car's sensors

 

Sorry if you were hoping for a different answer, please don't shoot the messenger - I can only give the honest answer, which I have. Please remember that a low rating PUNISHES me for my honest and prompt response, and I receive nothing for my time and answer until a positive rating is clicked.

Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.

 

Customer: replied 3 years ago.

you just confirmed what i origionally suspected, fuel problem.


your help and suggested actions are excellant.


regards XXXXX XXXXX

Expert:  Steve replied 3 years ago.
You are welcome. Please do not forget to CLICK ON a positive rating.
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