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2003 gmc envoy_sle_xl
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Discussion Starter · #1 ·
So the Envoy is begging for me to replace it, but I'm too stubborn because I love it. Last Friday on my drive from VA to PA (300miles) it wasn't running the greatest. Over the weekend the SES came on with a PO172 and PO400 code. I didn't have to go anywhere so I wasn't too worried. Monday comes around and I have to drive back to VA, I figured i would get it looked at once I got there, I drove for an hour and the Voy was running horrible. It was all bogged down, reving wierd, wouldn't shift right, so I turned around and brought it back.

The garage just called me and said that the problem was because the throttle body assembly was worn out and that's why it was running bad. It's $427 to get a part next day from GM and installed. Does this sound right? A malfunctioning throttle body will make it run bad and throw those codes? I have 155kmiles these days.

Thanks!
 

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2003 gmc envoy_sle_xl
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68 Posts
Discussion Starter · #3 ·
I can just clean it myself (I did so about 30k miles ago) would a dirty throttle body cause it to run rich?
 

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Discussion Starter · #6 ·
oops...PO440 (I think it was a evap small leak), I cleaned the throttle body and it still runs bad...the O2 sensor isn't that old. My scan tool shows they're both working fine. I tried to rev it up and record to see if it was opening fully or not but the video is bad. I think I'll see if someone can rev it so I can see if it opens.
 

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Discussion Starter · #8 ·
Last weekend I put in a new air filter, and changed the oil. The fuel filter was replaced about a month ago when I put in a new fuel pump. My scan tool has the TPS%...I'm not sure if that is for the throttle body or what but it seems to start running bad once it gets to 30%. I ordered a new one it will be here Monday, I'll put it on Wed and see if it works.
 

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Discussion Starter · #10 ·
The same setup that comes with it...has a new fram filter, which is not the problem.
 

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Discussion Starter · #14 ·
well it wasn't the throttle body assembly...looks like I'll be dropping it off at a GM dealer Tuesday for an expensive investigation!
 

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Discussion Starter · #17 ·
Sorry for the delay in the reply...

I haven't completely fixed it but I have improved the situation. I decided to unbolt my cat and completely ream it out, it was not the easiest thing in the world to do, but it did the job for now. This immediately was an improvement, the code was gone, it had lots of power and ran great. I still had the PO440 code, but no 172. About a month later I was driving across VA and had a misfire on #6, I replaced that coil no more misfire. Over the weekend (1/1/11) I replaced the rear brakes and noticed that the fuel tank is leaking from around the fill tube. I think this is a common problem on tanks from that year and most likely happened when I replaced the fuel pump. I'm sure this will be another fun weekend project!

Since all of my problems started when I replaced the fuel pump to me it would make sense that the leak from the fill tube caused the engine to run rich which clogged the cat...but I could be wrong!

So I'm not quite sure if I "fixed" it but it sure is running like there is no problem.
 
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