bad intake manifold gasket?

went to autozone today i had p0171 and p0174 codes. i checked all the vacuum line for leaks and my air intake to make sure nothing is loose. my MAF was cleaned 6k miles ago (but im going to clean it again) i searched around and it seems that guys in northern states have this problem when it is cold out. it also idol's rough like it has a big cam in it until it warms up. this is my first winter with the truck, but from what i have read there are different style intake manifold gaskets and mine is the old one causing these issues? could somone please give me the part number for the right gasket. i also plan on doing the knock sensors while im down there and replacing the harness. also would this hurt my gas mileage? because it has been crap lately and im not even driving like a pissed of teenager.:smile:

What year and model number?

the year is in my sig... 1999 and its a 1500 z71 all other mods are also listed in sig.

Yes, it is a very good chance you have a bad intake gasket. I speak from experience when i say, its best to go to the dealer and
get GM intake gaskets. The sets you get at an auto parts store sometimes wont fix the problem... lol ask me how i know. they should be black and green in color. GM p/n 89060413.

Also be sure to replace the knock sensor wire harness when you do the sensors.

yes all of this could hurt your mileage as well.

And yes, there were 2 designs from GM. a orange set, and a new improved green set. Make sure you get the green ones. Also when replacing the
knock sensors, i like to put some RTV sealant around the boot above the sensor where they sit in the valley. keeps a little more moisture out
of them that way.

Good luck and feel free to ask any questions if you have any!!

BT02CHEY hit the nail on the head.

btw check your fuel pressure before you change the gaskets.

thanks guys! and ill defiantly be doing the rtv trick to avoid having to redo work lol from the homework i have done it seems like if i dont disconnect the coolant line running to the TB i wont have to worry about a mess with coolant is this correct? i feel like this is such a simple question but i like to know what im expecting before i do this people say it only takes 2-3 hours depending on how many cold ones you're knocking back is this about right?:beer2:

I bet less than 2 hours if you go quick. I have done it before, but until 90mins is within reach.

Yes, thats exactly right.
I bypass that throttle body coolant line on all of mine, just to make it easier everytime i pull the throttle body off.
I dont believe there is any performance benefit from that, and i live in Texas, so i dont need it to warm anything up. I just
bypass it to be able to remove the throttle body alot quicker.

Quote:

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Originally Posted by mattjones

thanks guys! and ill defiantly be doing the rtv trick to avoid having to redo work lol from the homework i have done it seems like if i dont disconnect the coolant line running to the TB i wont have to worry about a mess with coolant is this correct? i feel like this is such a simple question but i like to know what im expecting before i do this people say it only takes 2-3 hours depending on how many cold ones you're knocking back is this about right?:beer2:

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After time a bit over a hour is possible. Its a easy job.

Quote:

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Originally Posted by bt02chevy

Yes, thats exactly right.
I bypass that throttle body coolant line on all of mine, just to make it easier everytime i pull the throttle body off.
I dont believe there is any performance benefit from that, and i live in Texas, so i dont need it to warm anything up. I just
bypass it to be able to remove the throttle body alot quicker.

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i looked into removing mine but for 4-5 months i dont see temps above 32 and some guys on here said its possible for the TB to "ice over" so i think its smarter for me to keep it. i cant wait to go back to Alabama where i dont have to worry about cold or snow!

Quote:

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Originally Posted by mattjones

i looked into removing mine but for 4-5 months i dont see temps above 32 and some guys on here said its possible for the TB to "ice over" so i think its smarter for me to keep it. i cant wait to go back to Alabama where i dont have to worry about cold or snow!

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Yeah, lol just to be safe I'd leave it intact for the time being. Lol