2003 Explorer with a 4.0L has a misfire. | Page 2 | Ford Explorer - Ford Ranger Forums - Serious Explorations
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2003 Explorer with a 4.0L has a misfire.

need2mud

Member
Joined
December 19, 2010
Messages
12
Reaction score
0
Year, Model & Trim Level
2003
Finally replaced the o2 sensors. Well three of them. Still the same. Going to replace the fourth soon. Still missing some, but does seem to run smoother and have more power. So hopefully the fourth sensor will be the problem.

And also we had someone tell us that it could be a cracked or leaking intake manifold, could that cause the problem?
 



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need2mud

Member
Joined
December 19, 2010
Messages
12
Reaction score
0
Year, Model & Trim Level
2003
Changed 3 of 4 o2 sensors. Didn't help with the misfire, but does run smoother and seems to have more power. Going to change the forth soon and see if that helps.

And also, I was told that it could be a cracked or leaking intake, sound valid?
 












vipersinu2

Well-Known Member
Joined
March 10, 2008
Messages
649
Reaction score
14
City, State
The Big City of Orange City, Florida
Year, Model & Trim Level
2019 Navigator 450hp
did changing all 4 o2 sensors help?
 






ryan606

New Member
Joined
August 19, 2011
Messages
1
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City, State
tx
Year, Model & Trim Level
05 Eddie Bauer
I had the same problem on my '05 4.0 and a mechanic told me i had a hole in my #5 cylinder so i took the engine out and took the heads off and saw no holes, sent the heads to another mechanic to be redone and got a call later that day from him telling me i had a broken valve spring. So you might want to check that if you have no more options before you dig a whole to deep. Goodluck
 






ERUSH97XLT

Well-Known Member
Joined
October 9, 2008
Messages
236
Reaction score
1
City, State
Omaha, NE
Year, Model & Trim Level
01 XLT, 03 XLT, 13 XLT
Hello,

I've always been interested in misfire problems with these engines.

All the aforementioned concerns and diagnoses are valid, but consider revisiting the ignition system. Check out some of my threads regarding what I've done to correct my misfires.

You never mentioned what brand names of ignition products you use. The Explorer ignition system can be finicky about what you use.

Good luck,

ERUSH
 






fredeb68

New Member
Joined
October 10, 2010
Messages
1
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City, State
Nashville
Year, Model & Trim Level
2003 Sport
My wife's 2003 Ford Explorer sport also has misfires in both cylinders 1 & 5. My dad came up this week and told me to test the coil/module to see if sparks were getting to the plugs. He brought a plug wire from my old explorer that I had at his house, and we put a new spark plug on the end of it. We then grounded the plug using a large alligator clip connected to the battery (we put it at the base of the plug), and tested each coil position. While every position fired, positions 1 & 5 both were very weak, and at times lost the spark. I had replaced the coil module 5 months ago when this issue first appeared, and still had the same problem continue. Do you think that replacing the PCM would solve this issue?
 






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