Contour Enthusiasts Group Archives Forums General Troubleshooting Rough idle, power loss, incr back pressure

I have a 97 GL 2.5 L that seems to have a loss of power. Cat was replaced last year @115,000 miles due to total loss of power. This totally fixed the problem, and the car was once again very fast; although check engine light came on shortly after; giving 02 sensor codes. I replaced all sensors ~2 months after that.

One year later at 150,000 miles, similar symptons (not a total loss of power yet, but I can tell it's not the same. Idle can be erratic, and acceleration can be jerky at high-torque/low RPM driving. Definitely don't have the passing power either. Car was put on Sun scope with no issues found; back pressure checked ok; codes were related to the Cat as well as IMRC.

If it is the Cat, can't I just remove it altogether (along with the resonater)(bypass 02 sensors), put in a straight pipe?

thanks -- don't have the data on the codes yet, but i'm taking it in to another shop, and i'll get them.

it's not a starting issue with the rpm -- just sporadically at idle; only bucking/jerking when attempting to accelerate gently (2000-4000 rpm) without downshifting. when floored, this goes away, but certainly don't have the power i should have; hence the backpressure suspicion.

main cat was all that needed replacing (according to backpressure test performed by mechanic). car ran as good as ever just from replacment of main cat. i fear that the root cause was not taken care of, and thus my cat may be plugged again.

Could be the secondaries are not closing correctly. Check the linkage for freedom and make sure the pesky bushings have not flown the coup.