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HardcoreKeith
New Member
- Joined
- Dec 25, 2009
- Messages
- 57
- Reaction score
- 0
- Points
- 0
- Vehicle Year
- 2003
- Make / Model
- Ford
- Engine Size
- Duratec 23
- Transmission
- Manual
When this happened to my truck I couldn't find very much info about it and it took me 3 days to figure out, but since I fixed it I've seen a couple other people mention it so I figured I'd post.
At one point recently my truck started misfiring a little and idling rough. The next day it got much worse. It started throwing P0171 (too lean) and P0301 (misfire cylinder 1) but I didn't figure out the significance until later. At first spraying combustible aerosols didn't seem to indicate a vacuum leak. I eventually found a post where someone mentioned that there is a crappy plastic end cap on the front end of the shaft that rotates the secondary butterflies in the intake manifold that can pop off and cause a huge vacuum leak. I sprayed starter fluid in this area to confirm and the idle rose. It's all the way on the front, bottom of the intake manifold, obscured by the power steering pump bracket.
Intake manifolds on ebay were more than I wanted to pay, so I JB-welded a dime into the spot where the plastic cap used to be. It solved the problem completely.
I hope this information saves someone else 2 days of diagnosis.
At one point recently my truck started misfiring a little and idling rough. The next day it got much worse. It started throwing P0171 (too lean) and P0301 (misfire cylinder 1) but I didn't figure out the significance until later. At first spraying combustible aerosols didn't seem to indicate a vacuum leak. I eventually found a post where someone mentioned that there is a crappy plastic end cap on the front end of the shaft that rotates the secondary butterflies in the intake manifold that can pop off and cause a huge vacuum leak. I sprayed starter fluid in this area to confirm and the idle rose. It's all the way on the front, bottom of the intake manifold, obscured by the power steering pump bracket.
Intake manifolds on ebay were more than I wanted to pay, so I JB-welded a dime into the spot where the plastic cap used to be. It solved the problem completely.
I hope this information saves someone else 2 days of diagnosis.
