redfishtd

F150torqued knows his stuff , this is worth trying it doesn't cost much . The 5.4 requires all to be perfect to run right . I believe puting plugs in a tight hole causes problems . Carbon around plug makes it run cool and can break plug forcing it in . I still use nickle on tips . .
By the way before I did front end I changed out all the injectors at 100k .
http://www.ford-trucks.com/forums/11...sfiring-2.html
good luck

Man from Mars

If you didn't see any change when the brake booster hose was put back on that says to me that you have a vacuum leak. Try it again. Create a vacuum leak and see if there is a change in the idle speed/roughness. If you have a 4x4 they are notorious for having leaks and cracks in the hard plastic tubing that's hidden inside the corrugated plastic sleeving. Hope you find it soon.

When the engine is cold the idle mixture is more rich and may hide the lean-ness of the vacuum leak. As the engine warms up the Fuel Injection is leaned out and this would reveal the vacuum leak condition.

jav1

Yeah- I had the same concern when the brake booster hose was unhooked... I didn't notice any obvious difference in running smoothness. Of course by the time we finally got it plugged in and the top of the intake re-assembled- the last thing on my mind was tearing back into the vacuum system. I really wanted to see if all that work on the timing chains, oil pump, tensioners and thrust bearing paid off. I was really hopeful on the first test drive and pleasantly "relieved" after reading about so many who have done this only to have the problems return in short order. And of course- I became one of those that same day. I didn't even get 10 trouble free miles.

But - yes. I think I may have a vacuum leak still. I suspect it's small and the vacuum reservoir is keeping up with it BUT- when I shut down the truck, I can hear a hissing air bleed near the firewall for about 30-45 seconds after I shut the truck off. I wasn't sure if this was normal?? Perhaps the vacuum reservoir leaking through a check valve?

Man from Mars

I have never heard a hissing sound after shutting off my engine. That sounds like a vacuum leak. The usual method for finding an unknown leak (one you can't hear) is to take a propane torch and turn on the gas (not lighted) and put the end near all the vacuum hoses and fittings with the engine running. When the idle speed increases you are near the vacuum leak. Or you might be able to find the leak by getting up inside the engine compartment and listening for the leak after you turn off the engine. A smoking cigarette could help locate the leak visually.

elricfate

I hear that for about ten seconds or so and then it stops. It's done that since I bought it in February. Normal for my 07, or seems normal.

jav1

yeah- I've read alot of people have it. It could also be refrigerant pressures equalizing if the the defrost was of... which I can't recall if it was and I haven't gone back and retried it.

BUT- since I've disconnected the VCT solenoids- it's been been running smooth, no ticking noises and no stumbling stalling.

Aeromech

I have a 2006 4x4 Lariat and my truck has always made the hissing sound at shut down. I believe it's the vacuum for the 4x4 system dumping. There's a reservoir under the battery tray.

My truck used to have a stumble at low rpm with a slight incline. I changed the plugs and insolators. Problem solved.

You can buy a smoke machine on eBay for less than $100 to check for vacuum leaks. I have one and it works great.

http://www.ebay.com/itm/EVAP-Smoke-M...812635&vxp=mtr

Man from Mars

Does the ticking noise sound only happen when the engine idle is rough? You're on the right track since you disconnected the VCT solenoids and the problem went away. I don't have that stuff on my 2 valve 4.6 so I can't help you with that. Lots of good info on these forums. Keep at it. You will feel great when you eventually discover and correct the problem. It's not far off now.

Here is one thread on VCT solenoid replacement:
https://www.f150forum.com/f4/vct-sol...cement-298402/

Blue Blood

I have hissing as well, always have, and no problems with the motor's performance. To me, seems to be related to the cooling system.