Hello all,

A newbie here looking for some help.

I have an issue with my 2005 F150 Lariat 5.4L with 99,000 miles that is driving me nuts. I had the plugs changed, all fluids changed, new fuel filter, air filter, etc.... changed and since that was done I get this rich or smell of exhaust coming thru my vents only when I come to a stop at traffic/stop sign. While in motion I don't get the smell. I have no issues with check engine light or mis-fires and the truck runs really good, it's just that foul smell coming thru the vents. I read online where this issue has occurred to many other individuals but have yet to see a resolution. I have taken the truck back to the guy (reputable mechanic) to have him look at it and he can't find anything. I did ask him did he put anti-seize on the plugs and he did. He put it where it should be and he put it where it shouldn't be (threads). I asked him to remove the anti-seize from the threads and to re-torque the plugs which he did and smell still exists. I then purchased new plugs again (this time Motorcraft plugs) and he kindly replaced the after market plugs with these and still smell exists. I have since taken it to the Ford dealer and they too can not find what is causing the smell. I wasn't too impressed with the Ford dealer since they said they found left over fuel residue on top of the valve cover or head and cleaned that off with a brake cleaner type solvent, this was about a month and half after problem started occurring so if that was the case the fuel would have evaporated by then. I don't know if they just did not want to take the time to look at it or if they were serious. I know that they did not mind charging me for that bit of work which resulted in nothing.

The mechanic that did the work originally did not take the fuel rail off to swap out the plugs and he even did a pressure check on all injectors to see if there were an issue with one of those. All injectors tested good with no leaks anywhere, even around fuel rail where the o-rings are, smell still there. The smell is so noticeable that I have to turn on the recirculate (off outside air) to live with it.

So I don't believe it to be a plug issue since they have been re-torqued, re-torqued again and then replaced with Motorcraft.

Looked around the fresh air intake to make sure nothing was being restricted with pulling in outside air instead of air under the hood, this looked clean as well.

Any ideas or suggestions would greatly be appreciated here. This smell was not present until all the above work was done. Love my truck but this smell has got to go.


Thanks in advance,
Scott

 

I probably should have mentioned that the only modification to the truck is a Magnaflow muffler only and a resonator (sp?), nothing under the hood has been modified.

Thanks again,
Scott

 

I think I'll try re-torqueing the plugs again to see if by chance one was missed. Got no clue after that.

 

I had a raw fuel smell come through the vents in the truck, more noticeable during cold starts. Turned out of of my plugs backed completely out and it was the blow by I could smell but I also had a ticking noise that went along with it

 

Thanks Craig, hopefully that'll be the case with mine. With all that has been done you'd think that this could not possibly be the case but you just never know.

Thanks again,

 

I would check them, especially if the mechanic never took the fuel rails off. He mustve had some time and patience to do it that way I was surprised to find the plug backed all the way out and I never had a miss or code thrown, just the smell in the cab. Good luck on the re-torque and keep me posted.