Exhaust fumes in cabin

[08navigator]

We have a 2015 navigator with the 3.5 Ecoboost. When starting the car to let it warm up in the morning, sitting at idle for a few minutes or anything similar to those two things, we get strong exhaust fumes in the cabin. I do not hear or see an exhaust leak but the strange thing is that the engine bay will smell like exhaust after a cold start with the wind going in the opposite direction.

The truck also idles like crap on a cold start and honestly sounds like a 200k mile beater. It drives great besides these issue.

Is there anything that could leak exhaust fumes in the engine bay(besides the exhaust manifolds)?

Is there a fix for the crap idle on cold start? We are still under both warranties also.

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[JExpedition07]

If the truck sounds like crap on a cold start and you smell exhaust you may have a popped stud or two causing a exhaust manifold leak....it happens occasionally on the ecoboost. Spark plugs ever done? If those are worn it may run rich.

Another thing to consider is to check torque on the plugs. I had exhaust and gas fumes in my 2007 cabin and couldn’t figure it out, I had new oem exhaust manifolds done etc. Ended up finding 4 (YES HALF) of the spark plugs were loose and were not torqued down in the heads. Replacing the plugs solved all my noises and fumes back in June. Just food for thought to check.

 

[aagitch]

If it's still covered under warranties I would definitely take it to the dealer and have them figure it out. It should idle nice and smooth even when cold.

 

[grdsman]

X2 on the spark plugs. You are due. My exhaust stank bad before I changed my plugs at 84k. As for the noise, that’s tough to tell without a video.


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[08navigator]

Thanks for the replies! I'll try to get a video of a cold start. The plugs were done at 35k miles but I used autolite iridium plugs instead of motorcraft. I guess step #1 would be to go back to oem and see if that helps.
I don't hear any exhaust leaks but I assume if it's small enough you won't hear it but will smell it.
Ordering plugs now.

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[aagitch]

How many miles are on it now since the plug change? Did the problem start right after changing the plugs?

 

[MidwestBoater]

These things run quite rich and a little rough on a cold start during the winter, creating rather stinky exhaust, which is easily gets sucked into the hvac vents at the base of the windshield. This has been my experience as well.

 

[08navigator]

Plugs were changed at 34k and now have 52k miles. I didn't really pay much attention to the cold starting after the change. My wife drives it mainly. We did take it on a 3000 mile+ vacation over the summer to Moab and up and down the mountain ranges on Colorado including pikes peak so I assume that's a bit rough on plugs.

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