Vacuum leaks, Cats, and Massive Power lossack this, any i | Ford Explorer Forums - Serious Explorations

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Vacuum leaks, Cats, and Massive Power lossack this, any i


New Member
May 12, 2016
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Year, Model & Trim Level
2003 Ford Explorer
About a year ago I developed a smaller vacuum leak that I couldn't find to save my life. I didn't really have the time to go without a car until I got it fixed, plus at the time I had no place to fix it. (Lived in Dorms) Now a year later the car has finally given me no choice...

2003 Ford Explorer Eddie Bauer 4.0L
CEL codes:

The thing still runs and drives but hardly idles due to the vacuum leak and what is now a misfire causing severe loss in power. I struggled to get above 65 on the freeway. I can hear the Vacuum leak very clearly and it sounds as if its coming from the intake manifold but spraying it with carb cleaner has done nothing to help me confirm this. I already know the Cat is going bad/is bad, but could that be causing all these codes? The first 4 are new after the misfire started... Just trying to figure out the best way to attack this, any input would be appreciated!

How many miles on the engine? Have you ever replaced the PCV valve? If it's stuck in the open position it'a like a huge vacuum leak to the system and it can possibly explain loss of power. I'm not saying that's the solution to all the problems but it's a part of maintenance to replace that PCV valve at some point and if it's never been done then you should change it out.

I don't know if the 2003 4.0L has the infamous "rubber elbow" but CHECK IT OUT as this issue is common on the 4.6L across many models of Fords and it's thrown off many a time the certified Ford mechanics.

Likely, you have other issues but I'm giving you a starting point. Some folks have better luck using propane gas torch to locate a vacuum leak than they do with carb cleaner.

check the pvc hose and elbow ..if you are spraying carb cleaner while checking for leaks, check around the intake manifold. and only when the engine is cold. running those conditions for long periods of time will kill the plugs, also it may be the coil pack, or ignition wires.

Any luck on your issue?