Truck turns off at a stop light

Tiny
RONNIE BAZAN
  • MEMBER
  • 2000 FORD EXPEDITION
  • 220,000 MILES
Ok, I took my expy to autozone and got codes p0171, p0174 I changed egr valve, sparkplugs, pcv valve. Also when I turn on my truck it stalls to turn on and also when it does turn on the rpm is high then goes down slowly and then it turns off. Please help!
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Wednesday, June 26th, 2013 AT 3:40 PM

4 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Check for engine vacuum leaks and check the idle air control valve (IAC). Both codes you listed are for a lean mixture which means you are getting too much air to the engine and not enough fuel. Most commonly, this is caused by a vacuum leak. That could also what is causing the engine to stall at an idle.

If you have the 5.4L V8, there is a vacuum hose on the rear of the throttle body that has a 90 degree bend in it. They commonly dry rot causing a vacuum leak. Check for that and any other leaks.
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Wednesday, June 26th, 2013 AT 7:19 PM
Tiny
SEANGRANT00
  • EXPERT
Could be leaking fuel pressure regulator, low fuel pressure, exhaust leaks before o2 sensors, fuel filter, clogged catalytic converters. If you push the throttle after it starts does it still die?
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Wednesday, June 26th, 2013 AT 7:20 PM
Tiny
RONNIE BAZAN
  • MEMBER
I changed the fuel filter it wasn't dirty. Im a girl and im new to this.I tryd checkn for vacuum leaks but its hard. The truck will start sometimesthe first and at times I have to do it like two to three times bfor it catches. After that my truck will run fine but like I said when I come to a stop it dies then it'll turn on. Its very rare that it won't die when I stop. How do I know if my iac valve is bad?I have tookn ut off tge throttle but left it plug in and I could hear the motor turn on but the spring inside it won't move or anything. Dont know if it's suppose to do that.I was guna ask you when I changed the pcv valve I just used simple heater hose.I didnt use no booy or anythng like that.
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Wednesday, June 26th, 2013 AT 7:34 PM
Tiny
RONNIE BAZAN
  • MEMBER
Im sorry no it dont die when I push the throttle. It will stay on then after awhile the truck will turn off on its own.
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Wednesday, June 26th, 2013 AT 7:36 PM

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