I have an 02 F150 4.6 and it is running super rough. At idle it "lopes" really bad. Taking off from a light is also really rough and at idle it starts to want to almost die after a hard idle. I just changed the fuel filter and cleaned the throttle body and map sensor. What else should I do (start with the least expensive)

Replace plugs? What kind do you recommend?


By the way the truck IS NOT throwing any codes.

 

I've replaced plugs and found coolant leaks onto the rear plugs. Could also be bad coils. Has anyone worked on it for you recently? If so what was done?

 

It has not had any recent work other then Ron changed the oil a few months back. Last Socaps meet it had the smog sensor replaced. This truck has always run perfect until now.

 

They all do, mine has two bad coils. I had a set of 4 good ones but I just donated 3 of them to a friend. Now I have a set of seven bad coils. They also tend to lose vac lines at the back of the intake manifold. I'd guess coil or two went bad with the rain the other day. It happens.

 

I just replaced the vac line today as well since it was kind of brittle. This started on Friday, Before the the rain.

 

Start pulling coil connectors until one of them doesn't change the idle. How many miles does your truck have? Mine went 200+ on the set.

 

Did that too with the plug (?) wires and injector plugs (?) also. Each one to me made it idle rougher. I have 63k on it.

 

That's nothing for milleage, you have a check engine light yet? I'd double check the vac lines and put in new plugs just to be sure. Motorcraft plugs are cheap enough and dependable.

 

The only time a check engine light came on was when we pulled a connector. Then we matched the code that came up in the code reader. It matched to what we were pulling. Then it cleared. With the way it's running you would think it would throw a code, but nope.

 

Hi Lori

Did this just happen all of a sudden, out of the blue?

 

yep, Friday when I was on my way home I noticed when I was sittting at the light it was kind of rough. It has gotten steadily worse since then. I drove it to Anaheim on Saturday you could tell it was missing on the freeway.Now it's so bad I am afraid to take it out of the driveway. I have an interview today and I will have to drive the 350, Ugh that's a beast!

 

I don't know jack about a 4.6...does it have some sort of an idle air control valve that's hooked to the air cleaner box? I had a rough idle problem on my '94 once and it turned out that the IAC valve wasn't closing like it should have been.

 

Hmm I have a fancy "intake" system on there. I also have a upgraded exhust. My 2 big mods haha I also wanted to note that I took it to the end of the street and when I got back the exhust made the tinking noise for a while. Like when it gets really hot. Ron seems to think it might be the cat plugged although he also said it seems like there is air flowing out the tailpipe. Sooo hmm I don't know jack about this either.

I'm thinking plugs and possible injector failure??? Don't want to pay Ford $105.00 to diagnose and then rip me off for parts and labor.

 

I'd be happy to bring my laptop over and test a few things if you'd like...I'm still learning how to use the software but I know I can check the injectors and whatever sensors are supported.

 

You have the means to test injectors? Ron seems to think one might be failing but we don't know how to figure out if this is true. I checked and it's 50 bucks a pop to buy them and if I had to replace all I would be screwed since I am broke. I would be forever in your debt if you could figure out if that was the problem.