Anyone that suspects a bad CAT, Change it!!!! A little expensive for the OBDII but well worth it. My 318in my 98' 1500 is like a completely different animal since it was changed. Well worth the money. I still have a bit of a spark knock when I get on it or when under a load though, anyone have any ideas?

 

plenum?? idk

 

im starting to notice a slight ping now too... only under load.. never happened before and i have the hypertech programmer with a low temp stat. maybe my plenium is going?

 

How difficult of a job to do the Plenum gasket myself??

 

+1 on plenum. look down in your tb for oil puddles inside plenum, you can see better if you remove tb.

its not hard, but its time consuming and you have to take a lot of stuff off. search recent posts for my pictures, and steve has a good diy sticky at the top. also see the tech articles on pavement sucks.
what begins to add up the cost is that once you have the top and front of the motor stripped, its a good time to do water pump, hoses, tune up, any other leaky gaskets, timing chain, etc.

if you are patient, have time, take your time, its fine. the hardest part for me was getting the #$@# fan off.

 

I can second this statement. I swapped the cat on mine and the ole girl has some fight in her now!!!!!!!!

 

Spring ping. Truck runs rich all winter and leaves carbon deposits behind. No problem as long as temps. stay low, but once the weather gets warmer, so do the carbon deposits. Seafoam or the stuff the dealer sells will fix it if you do it right.

Edit: you still may have a bad plenum. If your truck was built in the second half of the 2001 production cycle you should have a metal plenumgasket as opposed to the one made out of notebook paper that they used prior to that.

 

what kind of high flow cat would you reccomend?? you know best flow and easy to swap out