88 240 Passed NOX emissions test

[Ernie Ware]

The Mass Air Flow (MAF) was bad. I noticed the 240 had a loss of performance, but concluded it was getting old.

The dealer insisted the CAT was bad since it failed the temp test. I reminded him the Cat was less than 2 months old, the O2 sensor failed after 10k miles, and the CO and HC reading were real low (0.5 gpm) indicating a mixture problem. Looking at inspection reports from other vehicles, the CO and HC readings were between 3.0-5.5 gpm.

The Service Mgr. thought about the problem and had one of his service people drive the car on the highway and found the Cat was cooler than before he left. The MAF was replaced and the NOX dropped from 8.25 GPM to 1.75.

Thanks for the replies.