Rough running,fueling?.

[Tryw]

Following on from a previous thread i started, my s3 still seems to be running rough! it starts fine, drives away fine, but after a while of indeterminate time it feels like its having a partial sieze. You get a drop in power as if its on three cylinders then if you gun the throttle seems to clear, but its a bit like when your automatic choke is not working. or fuel starvation. gets to the stage its almost un-driveable! want to get it sorted for neil garners so any advice would be great! cheers all.!
PS I put in some injector cleaner today but may take a time to work through, and the car only did a handful of miles last year before i had it.

[steve j]

Rob, it could be a coil problem, breaking down with heat, mine did it two years ago with similar faults.

[glenrobbo]

I wonder if there is any rust or crud in the fuel tank obstructing the pump pick-up? If it's an ordinary steel tank & the car has been laid up for long periods with a low fuel level, it is one possibility.

[Loach1]

I like Glen '1000 posts's suggestion of a fuel delivery problem. Listen to see if the fuel pump whine changes when this occurs - if it is sucking air, it gets quite loud. The best way to check is with a fuel pressure gauge, but no everyone has one. If the car starts and initially runs fine, the fuel injectors must be doing ok. It could be heat related, so coil or ignition leads could be causing these symptoms. Other than that, maybe separate and clean every connector related to injection and ignition.

[Mr Clifford]

"Other than that, maybe separate and clean every connector related to injection and ignition."

Agree with above comment.

Had the same rough running when I first bought mine.

Garage carried out this work and immediately fixed the very rough (kangaroo ) running.

Car was fine when cold but after 5 minutes of running (hot) was as rough as hell !

[Tryw]

Thanks everyone!

[Niiige]

Fuel additives start to work quite quickly - after as few as 30 miles, but you need to empty the tank before the full benefit is revealed. Did you put a system clean additive in or just an injector ?

[Barkychoc]

Lots of possibilities but yellow connector under steering column or multiconnector on RHS on engine?

Injectors fire 3 at a time (oh yes they do!) so if you have a dodgy connection or short circuit etc you could be compromising 3 injectors.

[mycroft]

Yellow connector done .

[Tryw]

Niiige said:

Fuel additives start to work quite quickly - after as few as 30 miles, but you need to empty the tank before the full benefit is revealed. Did you put a system clean additive in or just an injector ?

just an injector.

[Spathodus77]

If you could borrow a star tester it would tell you if there are any electrical issues. I've had issues with the crud on the connectors going into the airflow meters a couple of times but this generally gives rough running after 30 mins of driving.

Star meter showed it up...the wiggle test is also useful.