ophidia

2008 STX 4.6 with 109k on it.

I bought this truck a few days ago. It had a rough idle so I cleaned then TB and MAF, replaced the air filter, and replaced the plugs with OE Motorcraft platinums. The idle is definitely better (plugs made the biggest difference, the stock nickel plugs were definitely done for) but it still idles a bit rough. You can feel it in the seat and steering wheel, and of course hear it.

Is a bit of a rough idle normal with a 4.6? If not, what else should I check? I've searched and most of the threads I've seen are either for 5.4's or don't really address my questions.

Thanks!

spinkter

What are your rpms in idle. Should be close to 750-800

ophidia

That's about where it is now. Before I did this work, it was about 550.

LUVmyDUX

Replace your PCV valve, $12 on amazon. Simple to do, 2mins tops, I did it and it improved my idle

ophidia

Oh yeah. Auto maintenance 101. I'll replace that. Derp. :P

ophidia

Could you link me to the one you got? I'm not finding a 12.00 one on there.

dereku

I have done everything to mine. made a huge difference but it still jiggles. I switched to pennzoil ultra last change, I was using platinum. It seems to idle a bit smoother but it is definitely smoother at the top end on the highway. It could be sludge related thats what this oil is suppose to eliminate the best.

ophidia

I'll need to change the oil shortly. I'll probably use Mobil 1 5W20 as Mobil 1 is what I always use in my cages. Maybe it'll help. I'm sure it's dino oil in there now.