FSI erratic/uneven running

My previous offer still stands, I can spare an hour or two if you care to visit. Do not expect much in the way of expertise, but you can bring your diagnostic kit to take whatever readings you wish from my FSI to compare to yours. I do not know anything about your OBDII kit but It might be worth scanning with my my VCDS kit and see if that turns anything up.

Andy
 
Just to add to this. My FSI had been running poorly (hesitation, refusing to start when hot unless fully depressed throttle etc) No error codes. I suspected the O2 sensor and despite the garage suggesting otherwise had them replace it. The car has been transformed. Starting much easier even when boiling hot. Will run on 95 RON although it much prefers 97. Economy improved. Pull away at junctions much better with more torque. Conclusion; even if the computer doesn't show an error code for sensors does not mean they are working right. I suspect Sainsbury fuel I had to use in Cornwall sometime ago. I normally fill using branded fuels. After filling with Sainsbury fuel the car refused to start when hot a few miles later and had played up until the change of sensor.
 
jtmalmesbury said:
Just to add to this. My FSI had been running poorly (hesitation, refusing to start when hot unless fully depressed throttle etc) No error codes. I suspected the O2 sensor and despite the garage suggesting otherwise had them replace it. The car has been transformed. Starting much easier even when boiling hot. Will run on 95 RON although it much prefers 97. Economy improved. Pull away at junctions much better with more torque. Conclusion; even if the computer doesn't show an error code for sensors does not mean they are working right. I suspect Sainsbury fuel I had to use in Cornwall sometime ago. I normally fill using branded fuels. After filling with Sainsbury fuel the car refused to start when hot a few miles later and had played up until the change of sensor.
Click to expand...

Thanks for sharing this little gold nugget of information that all too often gets overlooked and neglected! You raise an important point here in that Lamda sensors don't last for ever and are actually a service item at some pre determined mileage and one for all of us to be aware of!! Really weird though that this should happen after filling up with Supermarket fuel. Perhaps a coincidence?
 
The same thing happened with my FSI. Filled up at Sainsbury, drove 3 miles and stopped, engine hot and would not start. Called the RAC for help, and they said the same scenario was not new to them and help would arrive. After about 15 minutes waiting for them the engine started, cancelled with the RAC, drove home and has been fine ever since.

Makes you think.

Andy
 
I am convinced that supermarket fuel is not worth the risk. I have seen several examples (BMW) having to go in for major work blamed on supermarket fuel. Then I am told they use 'bulking' agents that effectively make the fuel go further and that the additives that you get in branded fuels are deleted on the spec for supermarkets. having dealt with supermarkets on other issues I suspect this could easily be the case. A few years ago i was driving a Suzuki vitara 1.6 petrol that had a single-point fuel injector. ran out and had to fill-up in Morrisons. the vehicle ran very poorly and fuel consumption rose dramatically until I had put 'proper' fuel in. Anecdotal? yes, Convinced? I am. Disappointing that sensors fail and the computer doesn't pick it up. More disappointing that garages ignore the evidence putting their faith in the computer.
 
ive been looking into all of your problems as i had the same thing with my newly bought a2 1.6fsi.

did all sort of repairs, coils, vacuum actuator, teared down intake and cleaned. Nothing different with idle issue..

then, finaly!

opened up the breather box on the rear of the engine. Cracked membrane and alot of junk..cleaned and made a temporary fix on the membrane with gasket on tube..

Put i back in.. every issue disapered after this. Hope this helps.
 
Varg327 said:
ive been looking into all of your problems as i had the same thing with my newly bought a2 1.6fsi.

did all sort of repairs, coils, vacuum actuator, teared down intake and cleaned. Nothing different with idle issue..

then, finaly!

opened up the breather box on the rear of the engine. Cracked membrane and alot of junk..cleaned and made a temporary fix on the membrane with gasket on tube..

Put i back in.. every issue disapered after this. Hope this helps.
Click to expand...
Good job, I did this too :)
 
Just a reminder, FSIs must run on 98/99 octane fuel (E5). 85 octane, E10 is not compatible with the FSI, due to 10% alcohol content. The engine is designed to run on 98/99 anyway, due to compression ratio and running temperature.
A scan with VCDS or OBD Eleven should be fine first thing you do.
Mac.
 
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