1991 Mercury Grand Marquis Q&A
1991 Mercury Grand Marquis Question: My car keeps failing emissions but only when it is idle. What can be the issue?
1991 is very easily disgnosed!! Maybe try another shop. However a lot of things can happen in a year's time! - pushrod
Agree with #1, these are easy. Can you post the HC, CO2, O2, and CO readings taken during testing? - cardocIII
agree with puhrod,seek a 2nd opinion - globalhelper