Slight tremble when accelerating

[Olivereric423]

I just bought a 2015 Expedition XLT 2 days ago and so far I love it. The biggest concerns for me are for one, as I speed up there is a slight tremble when it hits around 1500rpm. It goes away once I gain some speed but it's something I want to make sure is fixed soon. Secondly, tonight as I was at a drive through i noticed some excessive smoke from the exhaust as I idled. I hadn't noticed it until then, but that was also the first time I've idled at night. The smoke wasn't horrendous and it was a bit chilly so I'm hoping that it was nothing but my over thinking from having bought a lemon in the past. I'm not sure if these 2 things are related or not, but I've come here for some help and some knowledge from those who know the vehicle more and probably also have more car knowledge in general than I do. The man I bought it from got it as a partial trade on a vehicle he sold a few months ago so he didn't have a need for it so it's not been a daily driver or anything though he was told the cam phasers and timing chain were replaced roughly 40k miles ago. I drove it from the middle of Alabama to Crossville, TN after buying it with no problems other than the small tremble, and no codes popped up during that whole drive. I will check spark plugs in the morning as I'm hoping that could be it but any help would be great! Thanks!

 

[purevw]

I'd keep in mind that one of the byproducts of catalytic converters is water. Are you certain it is smoke and not steam you are seeing? If it truly is smoke, valve stem seals could cause a little smoke at idle, as could rings. The "tremble" might be difficult to help with if you can't at least indicate an area of the vehicle as the origin. Is it engine? Driveline? Differential?

 

[Calman2k]

My 17 steams a lot when it's cold, it will do it more in humid climates. The trembling on acceleration could be plugs or coil packs. I had the same thing and the engine was eating plugs. They wouldn't even last a few hundred miles. Turns out the trouble was the coil boot. I had the plugs changed at the right interval, but the boots had weathered and gotten hard. The shop cracked the boot and it was allowing the plug to short when the engine revved. Which caused the plug to crack. So I would check the plugs, but be prepared to change the coil packs, either because of a cracked boot or just a tired coil.

 

[Olivereric423]

I'd keep in mind that one of the byproducts of catalytic converters is water. Are you certain it is smoke and not steam you are seeing? If it truly is smoke, valve stem seals could cause a little smoke at idle, as could rings. The "tremble" might be difficult to help with if you can't at least indicate an area of the vehicle as the origin. Is it engine? Driveline? Differential?

It could absolutely be steam, however I've never had a vehicle steam as bad as it was. However it has not been as bad since that night so I'm assuming slightly colder weather mixed with humidity in the air was just causing it to steam pretty bad. As for the tremble, I can't pin point an exact area I'm just hoping not transmission. When cruising it is fine, however when I accelerate from the cruise, it feels like I'm driving over rumble strips. I've seen on some other forums that they had this issue and got a transmission flush and filter change which fixed the issue, but I have also seen several warnings against flushes so I'm hoping it's something else. I did have a p0420 code pop up today after hitting a bump so I'm thinking maybe the cat is clogged or going bad causing the rumble. I don't necessarily want to replace one but I'd rather that than the transmission

 

[jimz]

Water in gas?

 

[inmanlanier]

The steam is usually condensate that is in the tail pipes that boils off after warming up. If the 'smoke' persists well after startup I doubt that's steam.