View Full Version : '89 LS Idle Problems

09-10-2007, 05:56 PM
Hello all,
I hope that you can help me. I just replaced the catalytic converters and 02 sensors on my mother in-laws '89 Cougar LS. Now the idle is a little rough and when you put it in gear it gets worse. It ran fine before the work was done. It also has had the CO on in the dash for some time now. Do you guys and gals know of things that I can check out first?? The timing is spot on, has new plug wires and the auto trans was just serviced. Thank you for any help that you can give me.


09-10-2007, 08:12 PM
Why did you replace the converter and o/2? If CO means Check Engine light, well what are the codes?

There has got to be a LS web forum somewhere., or do you mean LX? (I didn't think the LS was made in 1989)

09-10-2007, 09:12 PM
sounds like maybe a plugs and wires or distributor(cap+rotor) issue to me. Did you disconnect the battery? may need to disconnect for a few minutes.

09-11-2007, 05:15 AM
Thank you for the replies. It's a LS... I replaced the cats because one of them had broken off inside and was rattling like crazy. Replaced the o2's when I was in there as preventative maintenance. Just did the cap and rotor not to long ago. I'll give the plugs a try, they may have been somewhat questionable. I did disconnect the battery for a few hours Sunday. Mother in-law said it was ok but I'm not sure what that means until I can see it. Is there a way to pull codes on the '89's? Thanks again.

09-11-2007, 07:56 PM
I forgot, Mercury... I had a LS that I used as a winter beater for 2 years. Digital dash and all.

OBDI code scanner will pull the codes. Test port is on the firewall on the passenger side in the corner.

09-11-2007, 09:46 PM
Thank you all for your help. I am somewhat new to the mn12 cars. I will be checking the codes this weekend, didn't realize that you could.... Oh and I now realize this is the super coupe forum and I'm asking about a regular LS (wasn't paying attention, just trying to get the car fixed). I'm sure you will be hearing from me soon about the father in-laws XR7 though. Thanks again you guys.