All,

Sorry if this has been covered but I cant seem to find an answer. I am new here so MODS if this should be in the engine forum please let me know.

My engine misfires all the time. On initial start it runs okay. Once under load after 3000rpm it shudders and there is no power at all. Under 0 load the car wont rev past 3800rpm.

I have replaced the plugs, wires, Crank Position Sensor, coils, and fuel filter and it is doing the same thing.

The car sat for the winter started about once a month and come spring its been doing this ever since. The codes that I get are misfire on x, y, z cylinders (varies everytime) and I always get the multipul random misfires.

Can anyone help me?

TIA,

Jared

 

Hey Jared. Welcome to the forum!
How long have you had your XF?

First off the rev under no load limit is a built in limit so you don't do damage to the engine.

Do the misfires affect all cyls or just selected ones?
Check for vacuum leaks.

 

Thanks for getting back to me so fast

I have had the XF for about 3 years. misfires affect all cyls. The car has been like this for over a year and
I am dying to enjoy this beast again.

Where should I begin with the vacuum stuff. I haven't spent a whole lot of time under the hood of it.

 

As far as vacuum leaks go, see if you can first hear any hissing sounds. Take a can of carb cleaner and start spraying the hell out of the areas you hear hissing. Whenever the engine smoothes out, that's the carb cleaner forming a temporary seal and enriching the AF ratio at the same time. Trouble shoot those areas.

 

Perfect

I will start tonight.

 

Isn't carb cleaner highly flammable? You might want to use something else.

 

Sounds like a wiring harness problem (short or intermittent open circuit). I would check the wiring harness for signs of rubbing or wear . Or maybe Mickey got in there over the winter and snacked on your wiring. It does happen more often than you think.
Good luck and let us know what you find.

 

I never thought of this. There was a nest under where the battery goes right next to the fuse panel.

I will try and take that all apart.

 

In regards to prior damage, I had the wrong car and edited my post.
Yea the nest is not a good sign.
Good luck

 

Is it a pain to get to the bottom of that fuse panel?

It looks really tight.

 

Look closely at all the wiring going into the ECU located in the plastic box next to the battery.

 

The engine compartment fuse panel is on the drivers side next to fender. You can take it apart pretty easily to check the wiring. The box next to the battery is the cars electronics(ECU, BCM, RCM) and the wiring goes out the back into the cabin. You can pull the battery and easily see what under it(not much). Mice can get into all sorts of areas and nibble you to insanity..... check the connections at your plugs and at the coil packs just to be sure they are good also. Hope you find the problem quickly.

 

I will start looking on Sunday

Thanks again for all the reply's.

 

He maybe correct on an additional fuse panel/block on the passenger side of the 04s

 

It sounds like a TPS (throttle position sensor) to me, when the TPS sends erratic information the system is designed to go into "limp" mode. When mine went out I would have the same issue.

 

Was it hard to fix?

 

No, the TPS is part of your throttle pedal.
When mine went out it would not throttle up quickly from an idle and while driving it would only slowly accelerate.