Ford F150 - Intake tubing

lftech2 · Posted: Wed Mar 26, 2008 5:48 pm Post subject: Intake tubing

The person I bought truck from cut a hole in the intake tubing between the air filter and throttle body. He put the blow back, (hose coming off the valve cover) in the hole. He says it's like a diesel intake and it'll be okay. How correct is he, and is this an okay thing to be done to intake? Thank you
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MJ

thefordmaniac · Posted: Wed Mar 26, 2008 6:00 pm Post subject:

the hole is after the air filter? not a good idea.

-mike
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Real Americans Drive American.

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Academy Ford Service Technician
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lftech2 · Posted: Wed Mar 26, 2008 6:08 pm Post subject:

Why is this bad?

lftech2 · Posted: Wed Mar 26, 2008 6:09 pm Post subject:

Why is this bad?

chargett · Posted: Thu Mar 27, 2008 7:05 am Post subject:

Dude, that guy is an idiot. He's pumping dirty HOT air into your intake. Diesels like/need hot air...not gas engines..Fix that asap!

vampyrekillerprime · Posted: Thu Mar 27, 2008 12:30 pm Post subject:

I don't think anyone is quite right on this one yet. It won't hurt anything at all. The engine burns dirty air all of the time, it's all part of the Positive Crankcase Ventilation (PCV) System.

Some exhaust air will always escape past the pistons. It then accumulates above the valves and rockers. On the driver's side valve cover, the hose normally routes from the valve cover to just before the airbox where the air filter installs. If this is the hose you are referring to, moving it won't have made much of a difference. You are not getting any significant air pressure so you're not injecting any air like a turbo would.

Some people will now say, but you can't do that, you're letting nasty dirty air back into the intake. Well of course you are, just like the PVC valve does on the OTHER VALVE COVER.

On your passenger side valve cover, on the rear part, is a small plastic valve in a rubber grommet. This is your PCV valve. When enough pressure builds up, it flows out the valve and through the hose DIRECTLY into the #8 port of the intake manifold. There is no filter.

So running a hose from the valve cover to the intake is just fine, no matter where you do it. There is no gain to it however, but I suppose the previous owner may have done it just thinking it would help. There is no improvement, but it won't cause any problems there either.

Incidently, Ford did come out with a TSB that recommends plugging the hole for the stock location, grabbing a longer hose, and routing the PCV valve output to a more central location on the intake. The TSB says where specifically. Apparently Ford found that by constantly venting the exhaust gases always into the #8 port it occasionally, after some time, could cause carbon build up on that cylinder. This not a common issue though with most detergents used in gasoline grade fuels today.

Overall though, just make sure the previous owner plugged all unused holes.

muddyford911 · Posted: Thu Mar 27, 2008 2:53 pm Post subject:

spray TB cleaner around the area where the two hoses are joined to make sure its sealed up good. or you could try vampy's trick...use a foot or two of garden hose and listen for hissing around the joined hoses.

lftech2 · Posted: Thu Mar 27, 2008 9:03 pm Post subject:

Where are these TSB upgrades available?

vampyrekillerprime · Posted: Fri Mar 28, 2008 7:25 am Post subject:

If you search this forum it's been posted here within the last 6 months. It's not really an upgrade, it's a technical service bulletin. If you've got a 1991 and haven't had any problems with your #8 cylinder by now, you're probably not going to.