Ford Forums banner

1 - 4 of 4 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter #1
2004 Navigator 5.4 RWD with 118Kmi.

The SUV has been intermittently struggling with acceleration from time to time and occasionally shutting off at stop lights. Since the problem has gotten worse, I brought it to the mechanic due to this and a fuel smell where I am inclined to believe the two issues are separate.

Originally the mechanic replaced the gas tank due to small cracks found in the tanks connectors and also said the evap code was due to 2 charcoal canisters in the evap system that should be replaced but now that the tank is replaced I decided to hold off on replacing the canisters since it does not smell as bad as it once did and the mechanic said the evap issue has nothing to do with the other issue I am having.

Although I can sometimes feel the issue at slower speeds, it has major hesitations trying to accelerate after idling above 45mph. For instance, when driving on the highway and trying to pass someone the vehicle starts to spurt and sputter and hesitate to accelerate. If I lay into the throttle more, the issue becomes more pronounced.

The mechanic said he saw some misfires on his scanner and recommended changing the spark plugs. A week and $280 later I briefly test drove the vehicle and did not notice any issues but I did not try getting up to highway speeds. The following day, I took it out and it stalled out 3 times at a stoplight a mile from home, I noticed the RPMs sounding like they were struggling to stay consistent and the issue of difficulty during acceleration was back, especially ay higher speeds.

I immediately brought it to the mechanic and he looked really stumped, I recommended we go on a test drive together so he could see exactly what I feel to be the issue and plan on doing that in the morning but I feel like I just spent $280 unnecessarily and that most mechanics are going to have me spending money on their guesses. Hopefully the forum has some knowledge on the issues of this engine, where the issues are intermittent at idil/slow speeds. Thanks for your help!
 

·
Super Moderator
Joined
·
19,168 Posts
Sounds like it could be an ignition coil breaking down intermittently , especially under load and causing misfire . When the plugs were out for replacing would have been a good idea to test cyl. compressions .Could also check for vac . leaks .
 

·
Registered
Joined
·
6 Posts
Discussion Starter #3
Sounds like it could be an ignition coil breaking down intermittently , especially under load and causing misfire . When the plugs were out for replacing would have been a good idea to test cyl. compressions .Could also check for vac . leaks .
Thanks for the help, the mechanic said he is inclined to believe the coil would be the next place to look as he sees misfiring on a particular cylinder, I have him working on letting me know what one and all 8 will cost to replace. After reading the forums, this is what I originally thought was the issue so I appreciate the feedback.
 

·
Super Moderator
Joined
·
19,168 Posts
If I seen a " misfiring on a particular cylinder," I would swap coil packs with another cyl. and see if misfire moved to that cyl. thereby verifying if coil faulty or not .Pretty basic stuff for any decent mechanic rather than guess and replace parts that may not be needed .
 
1 - 4 of 4 Posts
Top