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2002 gmc envoy_sle
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Discussion Starter · #1 ·
The check engine light flashes only if you push the car to hard other wise it doesnt come on.. the code we get is P0172.. there is no power and wants to make the transmission want to wait to shift and rev higher.. the car runs good at idle... can barely give it gas to run down the road once you go over 1/4 throttle it runs with minamal power and revs the transmission.. took to my local mechanis he ran his computer on it came up with same code changed the thottle position sensor that didnt work than changed the throttle body and drive and that didnt work and now says i dont know cause it runs fine at idle and doesnt constantly throw codes..
 

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2004 gmc
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26,181 Posts
What year and how many miles? Your profile is missing the year.

Your mechanic is a goof. What kind of computer told him that P0172 (excessively rich running) is at all connected to the pedal position or throttle body sensors? They have their own codes, not P0172.

Do you have access to a non-guess-master mechanic who won't obtain his training at YOUR expense? I hate hearing it when owners get ripped.

Anyway P0172 is excessive richness. Typically caused by excessive fuel pressure, vacuum leak, leaky injectors, saturated EVAP canister, restricted air intake flow (filter or hose), or crapped out O2 sensor.

Are you idling at 900 RPM instead of the expected 600?

Depending on your year, it might be as simple as a disconnected vacuum hose going to the fuel pressure regulator. That's hose #8 on the following diagram. Also make sure #8 is connected.
 

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2002 gmc envoy_sle
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3 Posts
Discussion Starter · #3 ·
my envoy is a 2002 157,000 miles.. runs at 600 rpm once warmed up...just went for another test run and it idles fine but once you put your foot into it it has no power sounds like its trying to suck lots of air which i have changed the air filter since this problem has started...rpm goes to like 3000 rpm and wont shift untill you let off the throttle....will eventually get to like 70 mph if you only give it minimal throttle....once stopped will idle just fine... only get flashing check engine light if i put the throttle to the floor and hold it there then when i let off it goes out...only code we get is p0172....
 

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2003 chevy trailblazer_ltz
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3 Posts
What year and how many miles? Your profile is missing the year.

Your mechanic is a goof. What kind of computer told him that P0172 (excessively rich running) is at all connected to the pedal position or throttle body sensors? They have their own codes, not P0172.

Do you have access to a non-guess-master mechanic who won't obtain his training at YOUR expense? I hate hearing it when owners get ripped.

Anyway P0172 is excessive richness. Typically caused by excessive fuel pressure, vacuum leak, leaky injectors, saturated EVAP canister, restricted air intake flow (filter or hose), or crapped out O2 sensor.

Are you idling at 900 RPM instead of the expected 600?

Depending on your year, it might be as simple as a disconnected vacuum hose going to the fuel pressure regulator. That's hose #8 on the following diagram. Also make sure #8 is connected.
My '03 TB is throwing the oxygen sensor code P0172 and idling at about 900 RPM now. As further history: a couple weeks ago on my way back from a 6.5 hr road trip, my #2 coil pack blew out, causing a dead fire miss on the cylinder. I had the coil and spark plug replaced on that cylinder. The SES light came back on quick after the repair and it was reading the camshaft position sensor and was stalling when I would slow down for a stop sometimes. The cam pos sensor was replaced and it's running fine now other than the oxygen sensor code and high RPMs. What would be the best course of action in this case? Could the upstream sensor be fried from having the excess fuel mixture from the miss fire cylinder 2 dumping onto it for 20 miles before I made it home and need replacing?
 
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