2004 Envoy will not go pass 15 miles.

dythaniel40

Original poster
Member
Aug 6, 2018
3
Houston
I started have issues with my truck. So when driving it starts off ok and get a speed of 30mph, but when it's fully warmed up. It is hard to increase speed pass 10mph. I have changed the map sensor, the uptake o2 sensor, and the shift solenoids. When put on the computer the only coded that showed up was o2 sensor. And it's still the same. Please help
 

Mounce

Member
Mar 29, 2014
13,667
Tuscaloosa, AL
How's it sound when you Rev it in park? Low pitched growl/grumble instead of a normal "vroom"? Rev up to about 3-4k as it should?

Might be worth checking your catalytic converter. What code are you getting exactly? Some codes with o2 sensors people will just assume a sensor is bad when in reality it's the cat.

Anyways my guess is plugged catalytic converter. Would need testing to confirm.
 

dythaniel40

Original poster
Member
Aug 6, 2018
3
Houston
How's it sound when you Rev it in park? Low pitched growl/grumble instead of a normal "vroom"? Rev up to about 3-4k as it should?

Might be worth checking your catalytic converter. What code are you getting exactly? Some codes with o2 sensors people will just assume a sensor is bad when in reality it's the cat.

Anyways my guess is plugged catalytic converter. Would need testing to confirm.
It sounds fine in park. And reverse but when I put it in drive it will not go pass 5 or 10mph. I can push the pedal all the way down and nothing.
 

Sparky

Member
Dec 4, 2011
12,927
Sounds like plugged cat.
 
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mrrsm

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Oct 22, 2015
7,639
Tampa Bay Area
Just to clarify what you have posted in your vehicle profile data... You list your Power Plant as being the GM 4.3L Ecotec V6. This would be an unusual swap in motor for the 2002-2009 Trailblazer and Envoy GMT360 Truck Line Series. Can you confirm that under the Hood... your engine actually looks like this one?

As for the CAT being plugged up ...Before pulling the Upstream O2 Sensor in order to investigate that possibility ...You should probably examine the Data between the Upstream Heated O2 Sensor Bank 1 Sensor 1 as possibly being STUCK RICH using a Scan Tool that can Read Live Data. But ...if the Downstream O2 Sensor is reading Very LEAN... then your Upstream O2 Sensor would need to be replaced. If NOT... then the check for the Pressure Relief leading to the CAT by removing the Upstream O2 Sensor should then be done to confirm the Clogged Cat as being the actual problem.

In these conditions... As soon as you take off down the street... the Bad (STUCK) Rich Condition Signal from the Upstream O2 Sensor...would signal the PCM to cut back on Fuel due to an imaginary Overly Rich Condition. The natural result would be a sudden Drop Off in Power down to the minimum acceptable level without causing the Engine to Stall. If the O2 Sensor R&R is called for... You should stick with using only the Heated O2 Sensors recommended by our other Members... and avoid Mixing rather than properly Matching the acceptable Brands... as PAIRS whenever possible. However... If the CAT proves to be The Culprit... an OEM flavor as the replacement is always preferred to any After-Market versions :
the-forgotten-inline-3_1600x0w.jpg
 
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