Gsragtop

So I picked up a troubled 2000 f150 today. It runs rough, lacks power, does not idle with The AC on and sometimes stalls. Yes she's a real winner. Lol..

When I got her the IAC was unplugged, and the tube running to the breather was undone an plugged up.. She had 12 codes stored, so I erased them to see what came back. Misfire on 5 and 7 came back with the iac plugged in the code for iac system came back, as did a lean code.

When I plugged the iac in with it still plugged nothing really happened. When I pulled the plug off there was a strong vacuum. I'm guessing it was wide open. Motor stalled. Plugged the breather in and restarted and there was a loud whistle, disconnected the hose and unplugged iac. The iac is supposed to be and looks fairly new.

The previous owner said his mechanic said the truck needed a new computer (which I doubt)

Where do I start looking for issues ??

Jbrew

What's "string vacuum" ?

Why did you pull the breather ? Btw, it doesn't have a plug or connector.

First thing I'd eliminate from the equation is the EGR valve. Since that is what will happen when they stick open. Just block it off, - that's the easiest and fastest way to determine.

Second, the converters. A plugged converter will cause those conditions.

Gsragtop

Should be strong vacuum.. Sorry, lol

The breather is not hooked up to anything, where it would connect to the iAC is plugged off. I tried to hook it back up to the iac and it did not sound good. So I put it back the way it was.

How do I block off the egr on the 4.6 triton ??

Thanks

Jbrew

Yea the breather doesn't connect to the IAC. The IAC has it's own intake tube. The breather connects to the valve cover.

Loosen the EGR valve and slide a plate in between that and the throttle body port.

Also post all DTC's that were stored. Since those would explain the problem. That would help tons, - ciphering the problem from the DTC set.

Gsragtop

But where does the breather run to ?? The valve cover to where ??, the large port on the (or I guess under the) iac what line should go there ??

Jbrew

With a 4.6L, the IAC intake runs from the intake to the IAC horn, from the horn to the IAC. I believe with that model the horn is very close to the IAC, if not, attached to it.

The breather connects separately and runs from the intake tube directly to the breather fitting on the drivers side cam cover (or valve cover as you call it). That entire connection is the breather (original set up).

The IAC has to be connected properly or you'll have air metering DTC's. As far as drivability concerns, doubtful, you'll run lean disconnected but not dangerously lean.

Keep in mind, anytime you make a change in air metering, you must disconnect the battery for a period of time to reset the KAM (KeepAliveMemory) to default into learn , -adaptive strategy for quick learn.

All that said, - it isn't the problem, - but it surely doesn't help and more less would be considered a contributing factor of.

Gsragtop

First of all thank you for your help so far, it is truly appreciated.

I have been searching for pics online now for about 30 min, and I think I get what you are talking about with the intake horn.. From what I can see there should be a rubber tube conected below the iac on one side and the other to a plastic box (i assume the horn).. However this is where I get stumped where would the rubber tube on the other side of the horn run to? I don't have any holes plugged or otherwise on my air intake (from the air filter housing to the throttle body) the entire thing which is factory from what I can tell is sealed.

My breather tube is just sitting there (with the horn attached btw).. That's why I thought it should connect to the iac as the tubes are the same size. Where should the breather run??

Thanks again !!

Gsragtop

Ok update. Found this pic, and my truck does not have part that goes between the intake box and the throttle body where the iac and breather should attach to. On my truck it's just a solid piece of rubber. That's possibly one of my issues and why it's not hooked up right.

Jbrew

Really ? No wonder it didn't make sense to you.

Yea, that's right, = black box is IAC horn. Basically it keeps the IAC from sounding off, - like a horn sound thru the intake that can be loud enough to be an annoyance.

Yea the bottom arrow connects to the top of the drivers side cam cover (valve cove) directly.

So, - the way it was, you said the breather was connected to the IAC ?

Man, - that's messed up! Guess you have your work cut out, - your going to have to go thru it...everything.

Gsragtop

Update- went to the junk yard and got a new air box. I installed it today and the truck is running much better (after disconnecting the battery for 10-15 min). It holds an idle much better with the air off, with the air on its still a little rough (only almost stalled once though). It's still running rough (hesitating/stumbling) all and all and still does not have much power, however it's also no longer throwing check engine lights (after running it for 10 min I still have no codes). There is a "horn" sound from the air cleaner assembly I can't figure out either.

I'm thinking about getting new coil packs from eBay and doing a full tune up as my next step. What do you recommend ??