Can't hurt to ask right?

So I have an 11 year old Ford F-150. 140k miles. I'm the only owner, I've maintained the thing oil changes, cooling system, filters etc. Anyhow, I had the engine rebuilt a year (about 6 thousand miles) ago. last year I had an inginition coil fail, I replaced it and the truck was drivng fine. Now the thing has developed one of those mysterious unreproducable, undiagnosable, spontaneous issues that has my mechanic and the stealership Ford pros scratching their heads.

Every so often, seemingly when it is hot outside after driving the thing 15 miles or so through stop and go traffic lights (Happens in the same area every time) The engine feels like it is devloping a large amount of back pressure, it bucks a little ni 3rd and 4th almost like a misfire or a bad coil but it isn't throwing any codes. If I let off the gas it feels like I'm standing on the brake and the truck pulls to the right pretty hard. When I pull over the get out there is a smell of hot plastic and usually there is a very fine, nearly invisily grey smoke emanating from the passenger side front wheel well. I've crawled all over the thing and can't find the source because the smoke is only visible in bright sunlight and it is then very feint but it appears to be coming from somewhere around the battery or main fuse box.

When I let it cool down for a couple hours it drives fine again, and the thing is that it doesn't happen every time I drive it so i haven't been able to get it in to a mechanic while the thing is happening.

Any ideas? I've pulled the tire, I don't see any obvious signs of damage, wear, burning on the in the axle/rotor area. I yanked the battery, nothign there, clean connection, no wires burned. I pulled the fuse box cover and couldn't find anything going on there.

I have no faith that the thing will make a trip anywhere so I can't use it for it's intended purpose of hauling and moving materials.

I'm at the point where I'm considering trading it in but it has been a pretty good vehicle, aside from this mess since I had the engine rebuilt it's in good working order and is worth more to me than the 1500 trade I'd get for it. In the shape it's in with the reliability issue I can't sell it to a person with a clean conscience.

Any ideas?

 

Catalytic Converter? Maybe the coil malfunction allowed fuel into the cat and now when it gets up to temperature it starts to break-down the catalyst in the exhaust. Possibly similar to Cats on the RX8 after a flooding incident. I don't know where they are located on the F-150 but maybe they are more under the engine bay and the smoke could escape through the wheel well. Just a thought.

It wouldn't explain the reason the truck is pulling to the right...maybe you have a sticking brake pad or wheel out of alignment? I know you said there was no strange wear marks but that's all I can think of at the moment.

 

That is a thought that hadn't crossed my mind. I'll have to take a look, the smoke could be coming from anywhere and just following the path of lease resistance.

I was sure I had figured it out and that it was a sticking brake but couldnt' find any evidence of anything going on there. I was going to go through the brake system as my next step, I did a little hard braking, and fooling with the E-Brake a week ago but that didn't seem to trigger it or resolve the symptoms of the pulling when it was happening.

Thanks for looking and giving it some thought.

 

what engine do you have? 4.2/ 4.6/ 5.4?

 

I have the 4.2liter V-6 4X2 manual transmission, bare bones model.

 

you have 6 ignition coils? Did you only replace the one?

 

I gotta admit to being a cheap *** there, I got the code and replaced the bad one, just for the parts I was looking at several hundred on the coils, and was considering ditching the truck. I thought that a bum coil could be responsible for the strange behaviour at speed, but it s the smoke and the pulling that have me thinking that it isn't a coil and without a code being thrown I'd have to replace em all, I was looking for ways I could trouble shoot the thing without throwing 4 to 5 hundred bucks at parts before identifying the real issue.

 

So your problem is the truck is pulling to the right?

The smell?

Pull to right could have something caught between the brakes.

Smell... plastic bag on CAT in fact it could have got caught up on the disc between calipers and is melting.

 

I had a v6 mustang, did the same thing, had to replace all the coils

 

Thank you sir, I appreciate the feedback, I guess I need to bite the bullet so i don't end up with a towing bill in addition to compounding the problem.

 

I had a plastic bag stuck up on my exhaust that wrapped around to my driveshaft. Yeah, some REAL scary noises coming from that RX-7 for a night.