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Code P0301 and Ocassional P0171

torqlox

Well-Known Member
Joined
April 6, 2007
Messages
221
Reaction score
7
City, State
Cape Coral, FL
Year, Model & Trim Level
99' Explorer XLS
Well, my 2000 Sport OHV has been acting up since I replaced the upper intake gaskets, DPFE, IAC, and EGR valves & hoses. Before these replacements, the truck was giving off a P0171 (Lean Bank One) code which is a common problem with leaky plenum gaskets on these trucks. The problem is that now it's throwing a P0301 (Cylinder #1 misfire), and I can't seem to detect the root of the problem.

Parts replaced within the last 6 months:
Both upstream O2 Sensors
Plugs & Wires
Coil Pack
IAC Valve
EGR Valve
DPFE Switch & hoses
Fuel Rail Gasket
Upper Plenum Gasket

I have not replaced the very lowest intake manifold gasket yet, but then again I have not heard any "sucking" sounds indicating any violent vacuum leaks. Injectors were cleaned and pulse tested well. Any ideas on where to go from here???
 
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torqlox

Well-Known Member
Joined
April 6, 2007
Messages
221
Reaction score
7
City, State
Cape Coral, FL
Year, Model & Trim Level
99' Explorer XLS
UPDATE: the hose that goes from under the throttle body (Evap return hose I believe) was completely collapsed and cracked all over. In an effort to start ruling out possibilities and weed out the false alarms, I replaced the entire assembly with tough 3/4 transmission cooler return line hose. The engine runs a tad better, but still getting a P0301 Cylinder #1 misfire. Also, I thought I might add that on my torque app, I read full activity on O2 sensor bank 2 sensor 1, but zero activity on bank 1 sensor 1. Still not sure if that is just my app that is not reading it or not, but I am going to troubleshoot further tonight.
 
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torqlox

Well-Known Member
Joined
April 6, 2007
Messages
221
Reaction score
7
City, State
Cape Coral, FL
Year, Model & Trim Level
99' Explorer XLS
Well, I pulled the lower IM, and found the Gasket to be in pretty bad condition, as well as the intake runners being overrun with gunk. I cleaned everything up and bought a gasket. There were no detectable vaccum leaks from the spray test, but I have seen a lot of people with misfire problems due to the lower IM gasket. Can anyone tell me if this could of been my case by the following pictures?

Before:
IMG_20140521_202344-1.jpg

IMG_20140521_202348-1.jpg

IMG_20140521_201825.jpg

IMG_20140521_201838.jpg


After:
IMG_20140521_221316-1.jpg

IMG_20140521_220637.jpg

IMG_20140521_220706.jpg
 
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superfly_1

New Member
Joined
February 22, 2013
Messages
3
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0
City, State
san diego ca
Year, Model & Trim Level
2001 ford explorer sport
did you ever figure it out ? i'm on the same boat without paddles
 
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