96 tbird - the exhaust saga continues

Well, I gave in and replaced the whole head pipe assembly to get rid of the P0420 and P0430 codes (catalyst efficiency below threshold on banks

1 and 2) I was getting (and the car was starting to sputter at stop lights). Now I get a different engine code - "P0402: EGR Flow Excessive". And the car still sputters at stop lights. Have I just exchanged one set of codes and 1 KilloDollars for a different set of codes? I also notice a tapping that seems to come from under the car when the car is accelerating to higher speeds (like entering a highway). The tapping speeds up and slows down with the RPM's of the engine.

My car is a '96 Tbird with the 4.6L engine and 142k miles.

How screwed am I?

Thanks in advance for any help.

Reply to
Brian Steele
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Here is an analysis (not mine) of that type of engine code and what one might do about it:

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It sounds to me like (a) the exhaust hangers are not stiff enough or out of position such that the pipes "tap" some other part of the car. And (b) the EGR regulator is a Moving Valve which is part of the EGR feedback system. So if the EGR valve gets extra motion from the 'tap's then the feedback system has to readjust the setting to compensate for the motion; this leads the computer to think that there is excessive flow - just a theory. - RM

Reply to
Rick Merrill

two things come to mind - I have a 4.6 and had to do both. The passages in between the manifold and the elbow to the throttle body get clogged from time to time and need cleaned out. Also, there is a sensor that watches EGR pressure and controls the valve (dpfe?). It can fail or gook up or the hose can fall off. It sits behind the throttle body next to the firewall - has an electrical connector and a hose.

You might Google newsgroups for P0402 or Ford P0402... lots of stuff about it...

PoD

Reply to
Paul of Dayton

Thanks to all who replied - I have an appt. with the dealer tomorrow morning (wonderful way to spend my day off). They're going to run the Dreaded Dealer Diagnostic$ and probably replace the DPFE and/or the EGR valve. From the posts I've read here and on the net, I'm convinced that I have EGR/DPFE problems, and I think I'm sufficiently braced for impact.

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Brian Steele

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Thomas Moats

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Brian Steele

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Thomas Moats

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