Today I got my bronco ('92 5.0) started and it ran for awhile then konked out, and it wouldn't start after that. I got my dad to come and help and eventually it started, but I had to hold the accelerator down otherwise it would shut off. Even after the engine warmed up, I still couldn't let off the accelerator or it would shut off. To drive it home, I had to hold the accelerator and break with my left foot, again otherwise it would shut off. Does anyone know why its doing this? It ran fine all the way home as long as I didn't let off the accelerator, but I can't let it idle. Any ideas? Thanks for the help.

 

idle air controller or the map sensor or simpler yet a vacumn leak. start with the vacumn leak first.

 

Ha buddy I just wrote a whole post on this. Check the Rough Idle and Check engine light post I put up. I am 100% sure it is a simple $5-8 fuel filter and a couple bottles of dry gas(alcohol). Just replace the fuel filter and put two bottles of the dry gas in your tank. You got bad fuel. Some where along the lines you got water in the tank. This could be from the gas station tanks or the tanker trucks who knows. But it is a easy 5 minute fix. I am 100% sure this is what it is trust me. The IAC is not the problem. Nor is it ignition related. It is simply clogging the fuel lines and injectors.
Mike

 

Go with BOJO's advice. Take it to a parts store and get the codes checked.

 

Don't Listen to these guys. I will bet money on it. It is a fuel filter and add dry gas.
Mike

 

Goble, you might be right, the truck not being able to idle started about a day after I filled the tank. Before I change the filter, I'm gonna check the MAP, TP, and the IAC sensor because I did have the check engine light come on and I have had it idle funny, like real high, and its cut off on me before.

 

My check engine light came on too. I went off once I put the dry gas in. I believe there are sensors in the injectors or some where along there that are telling you there have **** in them.
Mike

 

Well, I got the codes pulled today, it was just 172 and 173, nothing really to do with the idle. The guy at autozone said I should clean the air bypass valve. I'll try that tomorrow and see if its any better. O yea, the truck ran fine today, didn't idle funny or stall.

 

Code 172 indicates the O2 sensor senses a lean condition on bank 1 and 173 says it's rich on #1. Cleaning the bypass valve is a real good place to start. When it's indicating rich It might cause the computer to decrease the fuel to the point that the engine won't idle. The bypass valve is supposed to let more air in when idling. If it sticks in one place or another, it can cause both problems. My 88 Bronco would idle rough and die at red lights. Cleaning the bypass valve fixed that. It could be a O2 sensor going bad?

 

I don't think its an o2 sensor problem because I just changed mine out about three months ago. The old one must have not been that good, since when I put the new one in my gas mileage went up. About a month ago, I did get one other code, I forgot the exact number, but it said that the adaptive fuel lean limit was reached at part throttle. That code apeared twice that month and hasn't appeared this month at all. I didn't know what that was about.

 

I am telling you. The idle air control is not the problem. It is a simple $5 fuel filter. The computer is saying the fuel is too lean or not enough cause the filter is clogged with ****. I did this two days ago and saw for my self. When the filter is changed dry gas cleans and water in the system and cleans your injectors while its at it. Give the engine 1-3 minutes to idle and get the **** out of its system and you are good to go. Trust me. It will cost you $15 rather than bringing it to a mechanic and paying through the ***. Let me know
Mike

 

actually dry gas mixes with the water that is trapped in the fuel system and gives it propeties so as the engine can burn the water. the claening properties are just a slight benefit that you get when the water turns to steam and cleans the combustion chamber. dry gas will not clean the fuel injectors as it is not its purpose. getting a bad tank of gas is a rare occasion in this day and age because the pumps have filters and water cleaners in them. you can change the fuel filter but at idle it would have to be totaly cloggeg to make a difference.a plugged fuel filter will more than likely make it self known at
speed and under high load conditions.
your codes are because when the o2 sensor sees lean mixture it tries to compensate for it bt richening the mixture and when it does this it over compensates and that is why you get the rich mixture code also.
remove the idle air controller and clean it out with some throttle body cleaner and reinstall. if it is sticking open than there would be your lean mixturecode. fuel filters dont plug over night.
i think gobles reasoning is good and he just happenned to be lucky.
remember thta the simple things always trick us into thinking that it is serious. bob

 

Where is the IAC again? It the module by the throttle body right with the two wires and connector with two little screw right? I might just clean mine out too. Thanks
Mike

 

Mike, the IAC is a small cylinder that is attached to your throttle body (driver's side) by two bolts. If you are going to pull it and clean it, make sure you drop by the local parts store and get a new gasket.
Remove the two bolts and pull it off. You will see that it has two holes (one on either side of the throttle plates) and a metering valve to control airflow around the throttle plates when the engine is at idle (kinda like an itty bitty throttle body).
The air passages and metering valve have a tendency to get all gunked up. Just clean out the air passages, carefully manipulate the metering valve to ensure it operates freely. You can clean it with Throttle Body cleaner (NOT carb cleaner) or WD-40. WD-40 is actually a little better choice, as when you have finished cleaning it the residual lubricant will help the metering valve operate a little more freely.
If your IAC is severely gunked up, your best choice is just to replace it. Most auto parts stores carry them, as they are known to fail and Ford uses the same IAC on most engines. The part # for my wife's 2002 Mustang GT 4.6L IAC is the same as my 96 Bronco with a 5.0L.

Hope this helps.

 

Well i just finished cleaning the IAC. My truck idles a lot better and when I took it around the block, it didn't sputter at all when I let off the gas real fast. So far it looks like the problem is fixed, but it will take a day of two to make sure. Now all that is left to do is change the oil after I flooded the engine from trying to get it started in my first post. Thanks for the help guys.