300 Six Attitude problem
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300 Six Attitude problem
I have an 89 Bronco with a Fuel Injected 300 in it, and the darn thing stalls out at idle. Once it finally stays running, it runs rough, and when it gets on the expressway it runs fine. 
I've checked the fuel pressure regulator, replaced the fuel filter, and checked the fuel pressure and that'checked out ok. it has 160,000 miles without a rebuild, and I know that the compression is low but really nothing to worry about. The ignition system is ok also. I can't figure out what's wrong with it. is there anything that I'm forgetting to look at? someone shine a light on the problem and stop the madness!!!
I've checked the fuel pressure regulator, replaced the fuel filter, and checked the fuel pressure and that'checked out ok. it has 160,000 miles without a rebuild, and I know that the compression is low but really nothing to worry about. The ignition system is ok also. I can't figure out what's wrong with it. is there anything that I'm forgetting to look at? someone shine a light on the problem and stop the madness!!!
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From: Little Elm, TX
300 Six Attitude problem
Did you check the MAP sensor (On the firewall, passenger side)? My F150 had a similar problem, couldn't get any codes for it, but a friend that works for Ford service swapped it out and I haven't had any problems since.
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300 Six Attitude problem
It shouldn't be the EGR because I just replaced that about a month ago, after my check engine light came on. I pulled the small plug on the vacuum tree and it stopped it from stalling out when I start it, but it still tries to die out . I'm thinking that it's part compression , because it's not pulling enough air to stay running. That's why when I create a vacuum leak, it runs better. What dou you all think? And if it is, where is a good place to buy an engine rebuild kit?
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From: peoria, az
300 Six Attitude problem
When you induce an "air" leak into an injected motor it raises the idle because the computer sees the increase in air and adds fuel. This is the idea behind the idle air bypass valve.
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300 Six Attitude problem
I pulled the IAC off and the inside of it was covered with a black soot, it wasn't a carbon buildup it looked more like grease. do you think that is causing it?
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300 Six Attitude problem
Creating an air leak is not going to allow the computer to see the air. The computer only sees air that passes through the maf. I don't know too much about fuel injected 300's, is there a screw that allows air to bypass the throttle body? On my car it's called the Base Idle Set Screw, and if it's tightened to much it'll choke the idle off and stall the car. If there is one of these screws on the throttle body I suggest backing it out a bit and that should help.
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From: peoria, az
300 Six Attitude problem
The IAC or idle air bypass or whatever you want to call it covers a hole in the TB. This raises the idle. Why? because the computer saw that the engine got suddenly lean and it is going to add fuel to make it not lean.
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300 Six Attitude problem
I was talking about inducing a leak from, say, the atmosphere directly into the intake manifold (like disconnecting the hose to the PCV valve). I agree, the computer will see the additional air by adjusting that screw.
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300 Six Attitude problem
And if it's already running lean, it will flood the engine, causing it to stall. what my engine is doing is trying to stall out durring start up and durring idle. Once it finally calms down it runs rough. it has to be somthing with the air system, but I don't know what. it's not the IAC, TPS, or throttle plates. What else could it be?