catalytic convertor

[ginogag]

hi guys newbie here,
I got 2003 5.3 Tahoe, 127k miles . Few weeks ago while driving , pushed the truck a little and got a flashing cel and bad PINGING, light flashes for about 30 sec. Last week , same exact thing. Yesterday same thing , but lost a lot of power and light would intermittingly flash and stay on. Pulled it into station and mechanic got p300, and p301 code.....he said very common ploblem in this truck is intake manifold gasket. Today took it to MY MECHANIC and he said he physically disconnected the cat(s) and truck was running fine.
Question, is this a common problem? I am worried that im going to pay 1800 for FACTORY cats and 2 days later going to have same problem. Or maybe the first guy was right. Plus he found 3 broken intake manifold bolts...cost to repair ANOTHER $325 ...........IM going for big bucks.
Could this be ANYTHING else .....don't need any more surprises from the mechanic...
p.s. ...........he was very ADAMENT about not using aftermarket cat(s)..he said after 1 year I will probably start having problems again...Any truth to this ....
p.s.s. ....someone told me I should change egr valve also ??????thoughts

thanks
going broke

 

[rockenthebowtie]

Cat converters will not cause a misfire DTC.. the P0301 Indicates a misfire on #1cylinder.. if you have broken bolts on the upper intake yes you do want to address those first only I'm surprised it didn't have any lean codes P0171 or P0174..did he actually point out the broken bolts to you there should be five on each bank of the upper intake manifold on the inside of the fuel injector rails with a 5/16 hex bolt head... the thing about your mechanic taking off the cats sounds fishy you say it was missing and loosing power under a heavy throttle did he take it out with the cats off and open it up. . I think not... However about the aftermarket cats yea there only good for about a 1 year or so... dont recommend them.. so like I mentioned if the intake bolts are broken fix those first then if the problem persist you may have a ignition misfire such as a plug.. plug wire... or a coil. maybe even a bad injector but that would also set a lean code

 

[ginogag]

well, I saw the 3 broken bolts a few months ago and remembered ,so I told him to take a look while he gave me a price on the phone . I knew they were there , I wanted know if he saw them and he did. when he told me the cats were the prob, I asked why he didn't just try to change the o2 sensors first , he said he actually unbolted the cats( which I thought they were welded)?????...and the truck ran fine . But as I mentioned I got 2 codes from the OTHER guy p300 AND p301.....and a few days before that (I forgot to mention) the other guy actually got an 0101code???? im not a mechanic, so I really don't want to pay money, just to have to come back and pay another thousand for THIER incorrect diagnosis. Unfortunately , I got my back against the wall. Another thing that I don't understand is when I first dropped it off , he said he was going to put it on a SMOKE MACHINE. I didn't ask if he did because I was so dumdfounded with the price.
Anyway , now im stuck paying for new cats , not knowing if that REALLY the prob. Anymore input would be appreciated , By the way do you have a lot of expertise with this stuff.... have you worked on this vehicle ???
Thank you very much.....The more info the better. If u have any electrical questions ,just ask , electrician for 25 years .....thank you

 

[ginogag]

@rockingthebowtie....it was loosing power all the time when I brought it in to the shop (not just when I floored it) Would intake gasket cause those misfires????Would clogged cats affect gas mileage....just curious, thanks

 

[ginogag]

sorry , they are broken bolts on the EXHAUST MANIFOLD