2000 Ford Explorer - Vacuum leak?

2000 Ford Explorer with a V6 engine 4WD - Check Engine light is on. When it was on the diagnostic machine, it said that it was running lean. The check engine light came on immediately after the spark plugs were changed. Now, it is 18 degrees and when I started it, it idled super low and died. Then, I restarted it and gave it some gas. As long as I kept it above 2000 RPM, it ran. But, if I let off the gas, it idled low and then died. After it warmed up a bit, the idle was fine and it didn’t die. We’ve been told that it could be a vacuum leak. Do you think this is the problem? Or is it something else? What are some things we should check out?

If it idles just fine after it gets all warmed up then it is unlikely to be a vacuum leak. You might check for an intake manifold leak. I suppose its possible that a minor leak in the IM could seal itself up a bit once everything gets warmed up.

Check your coolant temperature sensor - if it isn’t reading correctly it will throw off the appropriate fuel/air mixture. In particular, the engine is supposed to run rich when it is cold. If the computer doesn’t get a good read on engine temp it may not be turning on enough “choke.”

Clean your idle air control (IAC) valve and throttle body. While the IAC is off, check its intake passages.

Check your fuel pressure, including how quickly the pressure bleeds off when the car is shut down, and how the pressure behaves on a cold start.

You might try cleaning the Mass Air Flow sensor with an aerosol MAF sensor cleaner.

The MAF sensor measures the amount of air entering the engine. If there’s contaminates on the MAF sensor it doesn’t measure the proper amount of air. When this happens the O2 sensors detect more oxygen in the exhaust gasses than what the amount of air the MAF sensor detects entering the engine. This then sets a code for a lean condition.

Also, the MAF sensor is one of the primary inputs to the computer. So if there’s a problem with the MAF sensor it can effect the engine idle under certain conditions.


Thanks for the info. We’ll check all of those things. Glad it’s more than likely not a vacuum leak. That could be tricky to find.

Leaking upper intake gaskets is the most likely culprit. Runs bad cold, seals itself when it warms. The best way to diagnose this is with a scanner

Also, liquid-film air filters (I’m looking at you, K & N) can, if you put too much fluid on them when you clean them, transfer that fluid to the wire for the MAF sensor, causing it to give faulty readings.

Hi, My car is having exactly the same problem and someone told me that it could be a vacuum leak and that i needed to change the oxygen sensors. Could you please tell me if the problem with your car was a vacuum leak and how it got taken care of? Thanks

I agree with the upper intake gasket, especually with the lean code, there is a bulletin from the dealer on this particular matter