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Mike V.
Mike V., Auto Service Technician
Category: Ford
Satisfied Customers: 25182
Experience:  25 years experience on all makes and models, Licensed NYS Inspector.
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I have a 99 Ford Explorer 4x4 with 4.0 SOHC engine. Today it

Customer Question

Hi, I have a 99 Ford Explorer 4x4 with 4.0 SOHC engine. Today it started just fine but dies when I let off the gas. It won't idle at all. It will run fine as long as I keep my foot on the gas a little. Any suggestions? Thanks for your help, Jamie.
Submitted: 1 year ago.
Category: Ford
Expert:  Mike V. replied 1 year ago.

Hi there,

Is the check engine light on when the engine is running?

Customer: replied 1 year ago.
No the check engine light does not come one.
Expert:  Mike V. replied 1 year ago.


This can sometimes be caused by a faulty mass air flow sensor or a dirty air filter. If it's been a while, check the air filter to make sure it's not plugged up. If it's not, then I would have you try unplugging the mass air filter and see if the truck will start and idle on it's own. This will make the check engine light come on, so don't be alarmed. We are just running a test. If it will idle with the maf unplugged, then it's the likely culprit and should be replaced.

This is the sensor that is mounted in the air duct work from the air filter up to the throttle body.

Check it out and let me know.

Please let me know what more I can do to assist you today. Also, please remember to rate my answer, Just Answer does not compensate me for my time and resources. Follow up questions are included in the price of your question. If you are using the free trial, a rating is still required.
Thank you so much!

Customer: replied 1 year ago.
That seems to be the problem. I unplugged the MAF sensor and it didn't die this time. How long do you suppose I can run with it unplugged?
Expert:  Mike V. replied 1 year ago.

Well, it may not want to drive properly with the maf unplugged. It basically regulates the fuel mixture so the computer adds the proper amount of fuel. I would not drive it long like that, but a short time should be fine.

Expert:  Mike V. replied 1 year ago.

Do you need further assistance with this?