Been driving my 04 x type with the same loss of power for well over a year now. It has become very apparent that something is wrong. The car loses power. One day last summer, I drove to Connecticut...roughly 4 hours away, and made it almost all the way home without any issue. I've heard everything from intake manifold gaskets, faulty fuel pump, MAF sensor, O2 sensor, fuel pressure sensor, vaccuum leaks, etc. Now, I have no way to smoke test for vacuum leaks. I cannot hear any hissing when i toggle with hoses or connections. I have pulled and cleaned the MAF sensor. To me, if it was the fuel pump, it would have died by now. This has been a problem for almost two years. Towards the end of the summer of 2013, it threw up CEL codes for both banks being too lean and the fuel pressure sensor circuit high input. I'm at a loss, very frustrated, and cannot find any solution to this problem.

 

jtravis, when was the last time you changed out the spark plugs? Did you use double platinum plugs when the change occurred (with the proper gap)? That would be something that could cause what you are seeing. The other thing that you may want to look at is the e-brake levers on the rear calipers. That can cause the rear brakes to drag and make it feel like the car is down on power. If you need me to go into detail about this, let me know.

This may be one of those cases that paying $100 to have a mechanic do a once over of the car and see what they can find may be financially beneficial. We can tell you replace 20 parts, but if it isn't the one that is bad, it was all changed for not.

 

Sounds like a real pain.

+1 on going to see a mechanic - driving along wondering how far you will get before the gremlins strike again would destroy anyones sang froid so well worth the money imo.

In the meanwhile, doing as much of the "routine" maintenance/replacement of things like gaskets/hoses and so on may help you to narrow down the issue and become more familiar with the car - sounds like you are well down that route anyways.

re: sticking e-brake - how much power are you losing? I expect the ammount of "sticking" will vary from one car to the next, but when I had that problem, the brakes were smokin' within 1 km, and I was pulled over and standing some distance from the vehicle well before 2km half expecting my next action would be to place a 911 call. Fortunately, it all cooled down, the brake seemed to release itself, and we were on our way soon enough.Although the car was noticeably sluggish during the short drive, I'd say the power loss wasn't that great - eg I didn't have a problem keeping up with traffic pulling away from lights, etc. So, long way of saying, if you think that is maybe the problem, I'd go buy a fire extinguisher before you do anything else! The quick fix, assuming you have an automatic and live in a reasonably flat area, is to stop using the e-brake until it gets permanently fixed.

 

Everything that I've been reading on here points to a vacuum leak. However, I've checked several different areas. I have not replaced the IMT O rings, which could be a possibility. On the spark plugs, I haven't changed them yet. Just noticing today that I can get the car up around 2500rpm before it starts hesitating. I'll keep searching and plugging away.