Catalytic Converter Code

[btolenti]

Does anyone know what a bad (or going bad) catalytic converter would throw for an error code? I am getting an erratic miss and check engine light on my 86 K-5. I already replaced the whole distributor and timed it properly.

Drove around today, and it did it again. Seemed to miss/stall and then the check engine light came on and stayed on... Then I could smell the sulfur smell from the cat. I know that if your truck is running rich it will make the exhaust smell like this. Is there something else I can check, or does a bad cat cause a code 42? Could it be the mixture control sensor or TPS on the carb???

I did a search, but came up with nothing...other than replace the HEI module and pickup, which I already did.

Also, was quoted 225 to replace the cat....does that sound expensive to anyone else but me???

 

[R72K5]

sounds expensive to me, only because i would go find best deal on new one and would replace it myself,

but 225 for a shop to do it would be about right.

good luck

 

[Hustler]

That price is expensive. Buy the cat yourself and if you can't do the work, then have a shop do it. They shouldn't charge more then $50 or $75. You can buy a good flowing Catco Cat for around $55 to $60

 

[Thunder]

Are all the parts new in the Dist? A code 42 is usually an issue with the distributor module or the magnetic pickup coil.
Also check all the connections and grounds for the ign system and where everything plugs into the ECM.

 

[btolenti]

yup, new pickup, module, coil, cap, rotor, wires, etc. etc...

Funny thing is, this didn't start until I did the tuneup and replaced the cap, rotor, plugs and wires...

 

[btolenti]

Also, what length of cat should I run. I checked summit and saw 50 or so listings!

 

[btolenti]

could a bad 02 sensor cause this too?

 

[Thunder]

Code 42 is ign electrical. A bad 02 usually wont cause a miss like you describe.And would throw codes related to 02 A bad cat will make your truck run sluggish and have low power but shouldn't cause an outright miss.
Beings this started after your tune up I would suspect the new dist. It may have a bad module or pick up. With the questionable quality of parts these days its not impossible for that to happen.. If you have an OHM meeter you can check the pickup coil. Pull the leads to it and put the ohm meeter between them. Readings should be 500-1500 ohms if out of specs the pick up is bad. Its best to check it when the engine is warm.
Also check the electrical connections. And make sure a vacume line isn't disconnected or broken.

 

[btolenti]

Well, no luck still. I checked everything Thunder suggested and all was well.

I wonder if my carb is in need of a rebuild. It has the mixture control, dual pump, etc.... Maybe that is the problem.

Funny thing is that I can peg the throttle in park, and the motor seems to run smooth, no misses, etc. It does have a small backfire during idle....more like a intermittent popping noise from the exhaust.

Any additional advice would be greatly appreciated.

THanks.