My car was running great until yesterday . I was doing a 600KM highway trip from Melbourne to Canberra and I topped up from half a tank of 95 at Albury APCO. After that the car would hesitate under light acceleration. The weird thing was cruising was fine and If I planted the foot acceleration was fine as well - it was just light acceleration where the jerking was. I suspect a clogged injector. I thought maybe the fuel was mistakenly the lower grade so after having just over a quarter of a tank left I filled up with 98. The jerking improved slightly but was still there. I am going to run down to a quarter of a tank again and this time I am going to try injector cleaner fluid. Sound like a plan?

 

Incidentally also my my 2.1L X-Type (and not long ago) I drove about 90km and arrived exactly at my destination, when the engine cut out when I was turning the car around to park on the other side of the street.
I parked the car, and 10 hours later, when I wanted to drive back, the car would not start anymore - just a few turns of the engine, with just enought power to drive 5m (meters!) and not more.
I got towed home, where I quickly found the issue: Simply a blocked fuel filter (and it is very easy to change, too). If they have not changed the way the fuel filter is connected between 2006 and 2009:
The fuel filter is under the car, in the rear section on the left. You just need something (small screwdriver or similar) to press those blue squares in to allow you to remove and swap the fuel filter...

 

If you suspect you may have inadvertently acquired some water in your fuel, then just running it down to 1/4 tank and refilling won't clear it as the water will remain separated and lying in a strata at the bottom of the tank.
Try adding some Meths to your tank as that binds with water and it can then be successfully passed through the fuel system and burnt off.
If you are down at a 1/4 of a tank (15 litres or so of contaminated petrol), start with adding only about 100ml of Meths.
It needs to blend so the meths binds with any water, so find a empty carpark or a quiet street and do some tight turns and/or virtual chicanes to get the fuel mixing well in the tank.

Hopefully that will remove any water or condensate that has set up residence in your tank without much fuss.
Good luck.

 

I was down to about 1/4 of a tank so i put a bottle of meths in and filled with 98 RON fuel. If the problem persists I will next try injector cleaner once I am down to 1/4 of a tank again.

 

I don't suspect the fuel as being the culprit as I called the servo and they hadn't received any other calls about the quality of the fuel. I suspect a partially blocked injector - but I put the meths in just in case.

 

I should have done it before but I put my exact symptoms into AI and came up with the result that the issue might be a dirty MAF sensor or possibly a vacuum leak. This is because the stuttering only exhibits at gentle acceleration - if I floor it there is no issue. Also at cruise the hesitation goes away. Makes sense when you think about it. The AI also gave me some codes to check to confirm whether it is either of these causes which I am going to do tonight after I get back from work. In the meantime I have put injector cleaner into my tank in case it is the injectors - too early to tell if this has made a difference as I have only done a few Ks since putting it in.

 

In case it does it uphill it'll probably be a failing coil.

 

It doesn't really make a difference what incline I am doing - the hesitation is under light throttle. I have checked for codes and found nothing but the P1111 (all systems clear) so i am suspecting a slightly blocked injector now. I have put injector cleaner in the tank and tonight I'll take her for a 40 min run to see if things improve.

 

Do you have a code reader with live data that you can read fuel trims and O2 readings? I don't think it's an injector, I suspect you're dealing with a vacuum leak.

 

No I don't have a code reader - I am no longer going to use the cheap ebay one I bought as it has made my car have a no crank condition. I have booked a smoke test to check for vacuum leaks at my local dealership (to be done after they fix the no crank issue).