Car still running rough after Catalytic Conv Change

[SHOfun 93]

Hey board! Yeah I am still alive, sholess for now, and have been reduced to the local sho "expert" around this town since all the shos in my sigs are now sold, wrecked, or traded in. But I have a quick question.

My buddy's 93 with only 66k on the clock was running really rough and when I went to diagnose what the problem was, after some time I looked under the car and saw the glowing red indicator of a clogged cat under the car. So I instructed him to take it to a local exhaust shop, have them cut out the clogged one and replace it. They did, but he has called me back again stating the car is still running rough....where are the likely culprits? He states that he just had wires/plugs done, and I have verified that they were run correctly on an earlier trip. So we are good both on spark, and on fuel ( I tested the schrader valve last trip too).

I guess my next guess is that possibly the 02 sensors might be fouled from having to rebreathe that horrible exhaust fumes? I guess I need to go and pull the codes for him here in about an hour and find out....

Good to see shoforum still going strong! :hpoop:

 

[Sexymeatball]

Hey look its my name...

What do you mean by running rough? Is the idle erratic but drives fine? Is the idle fine but it jumps and misses? Is it rough from a start or all the way through? It could be any number of things from the MAF, incorrect plugs/wires, TPS, etc. etc. Any codes? Have him pull the codes and see what he comes up with. Why not just direct him here instead of you acting as a go-between?

 

[SHOfun 93]

Guy is clueless on cars, and doesn't have a computer...plus he pays me to do the work for him...

 

[Sexymeatball]

[1] Guy is clueless on cars, and [2] doesn't have a computer...plus [3] he pays me to do the work for him...

Jeremy - 3
Jeremy - 0


Sounds like this is the best option then.

 

[LOUDSHO92]

Did they make sure that the entire exhaust system was cleared? Some of the material may have gone down the line and clogged it up.

 

[SHOtimer]

Well, are the cats still glowing red? I would think that they were running rich, which caused the cats to glow. If the o2's are original I would replace those to remove them out of the equation.

When my o2's went the car would idle like crap but still run 'ok', gas mileage sucked.

What type of plugs and wires were used? Using poor quality of either of those will make the car run like crap, also is their oil in the wells?

Have you checked for codes yet?

Good luck..

Doug

 

[SHOfun 93]

I have been waiting all day for the guy to call me with no luck, but I will pull the codes and get back to you guys...


He says that the cat problem is all fixed, but it is still running bad. Looks like the plug wires that he bought were the motorcrafts from the dealer OUCH!

 

[Brians_VT_SHO]

Mine did the same thing after I had a cat plug up. The back pressure did lots of lovely things..... Check for oil in the plug wells. Amazing what 1/2 a tube of dielectric grease will do to smooth out a rough running engine...

Brian