1998 Ford Contour Bank 1 cat inefficiency p0420

1998 FORD CONTOUR
155,000 MILES • 2.5L • V6 • FWD • AUTOMATIC
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CCLNGTHR
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Car had 2 codes, an EGR low flow P0401 and P0420 cat inefficient code. Pulled EGR and TB, cleaned out EGR passages, which were completely blocked. Scan tool reset (did not reset LTFT trims) Tested bank 1 and 2 LTFT, which were 2.3 bank 1 and 7.1 bank 2. P0420 returned within 15 miles. Reset ECU with scan tool, code returned in 50 miles. Noticed the cat monitor was on for about 20 miles of drive time. Code returned again with same drive length. LTFT tended to remain the same level. Did a hard reset to clear LTFT. Notice now that the bank 2 LTFT is now at 8.1 at idle, in park and bank 1 is at 3.9

Should the LTFT be within 2-3 points of each other? So far the bank 1 P0420 has not returned, but I suspect it may return. Do you think there may be a slight clog yet that is keeping the trims that far apart (under a load at cruise, it is even at 6.3) If the bank 1 cat code returns, do you think the cat is bad?
Sep 11, 2014 at 5:46 PM
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JACOBANDNICKOLAS
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The fuel trims seem high to me. Are you sure there isn't a vacuum leak or the EGR is stuck open? If you are dumping fuel, you could get the P0420.

Also, over the years, I have found that most times that code requires the cat to be replaced. Not always, but most times.
Sep 11, 2014 at 6:18 PM
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CCLNGTHR
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EGR now is operating fine. Removed it, looked slightly dirty, cleaned it good. Checked its operation on the bench with the vacuum pump. Moves freely. The clog was between the TB and EGR in the manifold, as well as the TB. Before the clog, checked the EGR with a vacuum pump and it was opening/closing fine.

On the dyno, at cruise, the LTFT is about 5.7-6.4 depending on vehicle speed and TPS level. In park, at idle, bank 2 LTFT is at 8.1 and bank 1 is at 3.9, but at throttle, both LTFT readings 0 out really fast, then rise up to about 6 at cruise

Vacuum reads about 18-22 at idle and it holds steady for 30 minutes (have not checked it for a longer period) with car running and it off. Need to test injectors on bank 1 for leakage, but don't suspect that. Car starts easy when it is hot and cold.

Would a MAF cleaning alter the LTFT readings? I suspect there is a clog somewhere in bank 1, since the LTFT is lower on that side. I also know that there always has been issues with the Contour getting the P0420 code on the V6 model Contours.
Sep 11, 2014 at 7:02 PM
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JACOBANDNICKOLAS
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Try cleaning the MAF and see if there is a change.
Sep 12, 2014 at 5:18 AM