check engine OBD code PO401
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Freshman User
Joined: Jan 2005
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Drove it today and still had the hesitation, etc. So, on a hunch I decided to try switching the vacuum lines on the DPFE. It seems to run better. They are set up the way it was before I tried changing anything. I don't think they are routed the way the diagrams show, but it seems to have corrected the problem. If it doesn't, I'll post a note and let you know what I find out.
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Well I have been having a similar problem and changed all the offending sensors and kept the battery cable off four an hour and started the vehicle and got the p300 code and when I looked at my tailpipe I was blowing lots of white smoke when it first started but after a while it was very thin white smoke. There was lots of moisture coming from the tailpipe and I don't know if that was condensation or what. I have been trying to take the upper intake manifold off to take a good look around but the pipe that goes from the egr valve back to the intake is stuck in there. Should I take a hammer and smack it a good one or are those pieces supposed to stay together.
Post Fiend
Joined: Jan 2003
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From: Connecticut
Originally Posted by tmal5
Well I have been having a similar problem and changed all the offending sensors and kept the battery cable off four an hour and started the vehicle and got the p300 code and when I looked at my tailpipe I was blowing lots of white smoke when it first started but after a while it was very thin white smoke. There was lots of moisture coming from the tailpipe and I don't know if that was condensation or what. I have been trying to take the upper intake manifold off to take a good look around but the pipe that goes from the egr valve back to the intake is stuck in there. Should I take a hammer and smack it a good one or are those pieces supposed to stay together.
White smoke and misfires can indicate a problem with either the lower intake gasket, a headgasket, or the heads themselves. But you have to consider everything. I'm wondering why, for example, a specific cylinder misfire code hasn't been thrown, just the P0300.
If your truck has the 4.0L, this might help you figure some things out:
4.0L OHV Upper Engine Gasket Replacement (PDF)
Elder User
Joined: Jul 2005
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Also make sure you use the correct hoses... They make a special heat-resistant hoses just for the dpfe's...
Regular vacuum hose will melt or deteriorate internally, and a lot of time that melted crud will get pushed up into the sensor and cause problems.
If your parts store doesn't have any check out a ford dealer.. only a few dollars a foot.
Of course if you have used this hose, then disregard this message! It will self-destruct in ten seconds... nine... eight...
Regular vacuum hose will melt or deteriorate internally, and a lot of time that melted crud will get pushed up into the sensor and cause problems.
If your parts store doesn't have any check out a ford dealer.. only a few dollars a foot.
Of course if you have used this hose, then disregard this message! It will self-destruct in ten seconds... nine... eight...
New User
Joined: Jul 2005
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Well it will eventually show 1 and 5 plugs misfiring if I let it run long enough but as far as I can tell that information just won't help me. I agree that the white smoke is probably caused by some coolant leaking into the combustion system some how. I managed to get the upper intake manifold off but had to take the egr tube with it becasue I could not seperate it even after I took it off the engine. I am now going to run a compression test, but I need to find an extension for my air hose because it is to short to reach the tread in the head. I bought an anti-fouler attachment that you put on spark plugs but the tread starts to deep on those also, which leaves me in the same perdicament. Hopefully today I will get the compression test done. Oh by the way, this is a mazda b4000 1997 with 200,000 mi. on it. From about 20,000 miles ago I started loosing power and gas milage and now it is really bad, so now I want to fix it.
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