I have a Ford Bronco with a 5.8 engine. My son-in-law and I replaced then head and intake gaskets on it a month ago. Since then, the engine starts and runs great. But after it runs (heats up)and you put it in gear (with your foot on the brake) it doesn't want to idle. some times it dies right away, or it runs rough while in gear and dies when you hit the brake.
Country: United StatesMake: FordModel: BroncoYear: 1992Engine: 5.8
Timed the engine, new distributor, replaced TP valve, replacedthe other two sensors (can't remember their names)on the throttle body, check fuel pressure at the fuel rail.
Hello, I will try to help. Did you clean the throttle body and plate by chance? Usually a stumbling problem at idle can be caused by dirt and varnish in the throttle body, Take some carb cleaner, and old toothbrush and a rag and get all the dirt and varnish out of the throttle body and off the throttle plate, Clean the IAC valve as well (Idle air control) Those valves can stick, If it's original. I'd go ahead and replace the idle air control vavle as well. Disconnect the battery for 5 minutes after cleaning the throttle body so the processor can re-learn the adaptive idle. Let the engine sit and idle for 5 minutes, then turn on the air and let it sit at idle for another 5 minutes. here is a link to the idle air control valve. http://www.autopartswarehouse.com/details/QQFordQQBroncoQQStandardQQIdle_Control_ValveQQ19911992QQSIAC33.html?apwcid=P1135867996W43b3f85c7ab9e&apwid6apZOK8
ASE certified. Auto Transmission rebuilder for Ford Motor Co. from 91 to 2000
It starts and idles great. During acceleration down the road, it crackles and back fires until I am up to highway speed. Once there, I can drive with no problems. It doesn't seem to have the pick up as before.
Is the check engine light on by chance?
No, it isn't. The gas pedal feels like I'm stepping on a balloon when I accelerate. When I travel a few miles at 55 mph, it seems to run good. When I slow down steppingstone ( after engine is good and hot) it will die. It is kind of hard to start, but I hold the pedal to the floor, then it starts.
Interesting, I've looked over this question fully. You sure you got all the rocker arms bolted down and tight? The popping and cracking under acceleration is what I'm referring to.
I will look into that and double check! Good call!
Check the fuel pressure regulator too, see if it will hold vacuum. otherwise raw fuel gets dumped into the engine.
I hooked up the fuel pressure gauge and wedged it under the windshield wiper on the drivers side and monitored it in different situations while at idle and driving - it held fine.
ok, does fuel pressure increase 10 lbs or so when you hit the throttle. then back off slightly when your foot is off the gas?
It didn't move
Fuel pressure stayed between 38 -40
OK, spray the cap rotor and wires down, and look for spark arcing anywhere. did you replace the rotor? I know you said a new distributor? did it come with a cap and rotor?
The rotor was replaced new with the distributor and cap.
I will spray it down and check
OK, let me know what you find.