I have the v10 in my X. It has 139000 miles. My problem is my truck will like cut in and out sometimes. If the tank is below 1/2 tank it does it all the time. If you are giving it gas you will never feel anything only at cruising speeds or low speeds. Any ideas what could be causing my problems.

 

Moved to the V10 forum.

Stewart

 

What is the fuel pressure measured at the test port?
Has the fuel filter ever been changed?
Are there any pending codes for misfiring?
What is the battery voltage when running?

 

Fuel pressure is good. Replaced the fuel filter about 2 months ago when it started. Has a brand new battery and it test good as well.

 

Also there is no codes for misfire. I installed all new coil packs and spark plugs.

 

Misfire codes do not always get set even though it is misfiring.
You'll need to get a computer reader that can show the data on misfires detected.
It takes a lot of misfires, if ever with OBD I, to set a code.
Even my OBD II 2003 Exped will misfire and not post a code.
Can you tell if it is misfiring at idle?
The occasional chug because it is not running smooth.
When mine were misfiring it didn't feel like it was cutting out.
Is it cutting out clean - just stops firing, then goes?
Or is it a surging with a lack of power?
Cutting out clean is usually electrical and surging is fuel delivery/mixture.
A reader will help narrow things down to a cylinder/s.
You might have a faulty fuel injector or bad wiring to the COP or injector.
Has the MAF been cleaned lately?

 

The problem got worse. Anytime it is running it seems like it is cutting out or losing power. When I was pulling with it at about 65 mph the X would cut out all the time until I got it above 70mph. I finally broke down and took it to the shop. After about 2 weeks of having it they still cant come up with anything. I did pick it up one night from them to drive it and it ran great. I put gas in it that night and woke up the next morning and ran like crap even worse than before. They have check fuel pressure, spark plugs, coil packs, etc. The computer does not show any codes at all. Any help would be great.

 

Check the throttle position sensor and the crank position sensor.
If the throttle position sensor is outputting inconsistent readings that would causing weird things to happen.
Maybe the sensor works fine above 70 because you don't usually go that fast.
When you say "pulling with it" do you mean towing? With the increased load of towing is the trans staying in OD consistently?
Is the loss of power a surging? That would tend to be fuel related. Was the fuel pressure measured at idle and while driving under load?
If the loss of power is cutting clean that would tend to be electrical. Check all the connections and grounds.

 

Now it does it all the time. When you go to take off it sounds like you are giving it gas and letting off the gas. Then if you floor it. It will take off and go.