94 talon awd tsi hesitates during acceleration

[bigpula]

Hello

I filled up my car. Left the gas station, and the car had a big back fire (first one ever). I thought it was bad gas, so I emptied out the tank and change the fuel filter. But since the back fire the car has been hesitating on acceleration. It only hesitates when tou hit the gas,rpm's can be high or low and it won't hesitate unless you press the gas harder. Let off the gas a little and it runs fine until you hit the gas harder then it hesitates again. I have also changed the crank angle sensor. Any help would be appreciated. The tps sensor seems to be O.K.

[MrZ]

bigpula;
Have you checked your valve timing? I think your belt may have jumped and your valve timing is off now. If it has, don't drive the car until you change the belt.

In case you're not sure how to check valve timing;

Pull the timing cover top off. Jog the crank around to TDC. There are timing marks on each of your cam sprockets, they should be facing each other (left side at 3 oclock, right side at 9 oclock. If it's opposite of that, rotate the crank around one more time. If the marks aren't lined up when you have the crank at TDC, you've found the problem.

Mark

[bigpula]

Mark:
Thank you for the suggestion, we just checked the pulleys and the marks are right on. If you have any other suggestions, please let me know. Thank you.

Alex.

[MrZ]

bigpula;
My guess is that it's vacuum or intake related. The fact that it happened so suddenly is intriguing. I can only suggest to go over the obvious things first, check all the vacuum hoses for leaks, make sure the intake duct work is tight between the throtte body and the air filter housing, check the duct hose for cracks too. Have you checked the ignition timing?

I suppose it's also possible that something's happened within the fuel system, i.e., perhaps the pressure regulator isn't working properly (which is another vacuum hose you should check).

Sounds like you know your way around an engine block already, so I don't know that I'm giving you any ideas you haven't already thought of.

Good luck to you!

Mark