Originally Posted By: Cujet
I agree with an above post.
It sounds like your ignition timing is being "pulled" for some reason. When this happens, uneven acceleration is often the result, coupled with lack of power.
1) It's possible your knock sensor is bad
2) It's possible your knock sensor is picking up some other noise
3) It's possible your octane is too low for summer conditions
4) It's possible that the air/fuel ratio is promoting knock
The first thing I'd try is to disconnect the knock sensor, as I'm fairly sure you've tried premium fuel from a name brand, high quality (and different) gas station.
The only thing is that timing is not being pulled. I sit there and stare at the timing while driving along, accelerating, decelerating, and don't notice any anomalies. The same goes for all the other data I can poll, be it O2 sensor, fuel trims, MAF sensor, MAP sensor, engine load... Otherwise, I agree. I will try disconnecting the knock sensor. I have tried higher octane fuel to experiment but did not notice any change.
Originally Posted By: Merkava_4
Does the car downshift like it's supposed to when passing a car on the freeway?
The car downshifts normally.
Originally Posted By: Rosetta
That's lack of fuel supply. Try 1st stage fuel pump or 1st stage injectors could be weak. Only cure is to replace some of these parts
When I tested fuel pressure at the rail, it sits right where it should be at idle and WOT.
The latest "test" I tried, since the car is about to go on a 1000 mile trip, was to pull the (new) O2 sensor completely out of the manifold and try driving briefly. I would swear the problems went away, though I am not sure (it's hard to tell since the car is so loud which makes it seem faster regardless, and I did not want to do more than 2 accelerations with exhaust aimed right at the firewall). That, to me, points to an exhaust restriction, although it didn't show as such with a vacuum gauge...