Rough idle/ stall cold

[Brian Sprague]

Working on 01 Ford explorer sport trac with 4.0 vin E

when starting below 30 degrees Farenheit the vehicle will run rough and stall.

The problem only lasts a couple minutes and straightens out. Seems like the problem starts when the vehicle idle speed is coming down after initial start. No codes were in the system until recently. The only code was bank 2 sensor 1 oxygen sensor indicate lean. How could the O2 sensor create a problem at cold start when in open loop. Tried throwing some parts at it with no luck. Tried MAF and DPFE sensors. Fuel pressure was extremely high and replacement fuel pump brought pressure to spec. Vehicle still exibits cold run problem.

NEED SOME HELP FIGURING THIS ON OUT!!!!!

 

[Ben Poche]

try link

 

[Rodger Tellefson]

I agree with bpoche.

 

[Tom Higbee]

Check to common cracked elbow issue if it's a job 2....lots of posts about it..

 

[Todd Z]

Here is your problem...

Todd Z

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[Brian Sprague]

I don't have the vehicle here right now but, wouldn't the cracked vacuum line be causing problems hot and cold? This vehicle is perfect after approx 2 minutes of running. I will look at the vacuum hose but the IAC counts seem to be high enough. I would think an air intake leak would cause low IAC counts

 

[Todd Z]

The iac is an idle air control valve that opens and closes to help keep the engine idling when a sudden load is applied at idle. Most small to medium vacuum leaks will cause a vehicle to run like junk at idle and seem to be ok once warm. The reason for this is the o2 sensors are not functioning until the engine warms up, so they can take over and control the fuel mixture, but at idle cold they are not in use, and the engine is running on the basic inputs.

Todd Z

 

[Bill M]

I have the same problem. I have tried everything except going to the dealer. My truck does not have the infamous cracked elbow as in the job 2 trucks. Let me know if you figure this problem out. thanks