03 Envoy 4.2 Signfantly loses power uphill - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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  #1  
Old 07-20-2019, 05:22 PM
Monte27 Monte27 is offline
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2003 GMC Envoy SLE
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Question 03 Envoy 4.2 Signfantly loses power uphill

My envoy majorly loses power on any uphill grade. Good coils, plugs, air cleaner, and motr runs smooth, Has less power the hot it gets. Code reader shows p0440, Changed gas cap...No improvement. Any suggestions before I start randomly changing solenoids and hoses in the Evap system. And Does any malfunction in the evap system cause this lack of power?
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  #2  
Old 07-20-2019, 06:47 PM
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EnvoyBoy2004 EnvoyBoy2004 is offline
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Has fuel filter ever been changed? There is also a possibility of a clogged catalytic converter.

In order to diagnose this issue, a scan tool needs to be hooked up and certain parameters monitored when problem occurs.
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Old 07-20-2019, 07:24 PM
Monte27 Monte27 is offline
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Quote:
Originally Posted by EnvoyBoy2004 View Post
Has fuel filter ever been changed? There is also a possibility of a clogged catalytic converter.

In order to diagnose this issue, a scan tool needs to be hooked up and certain parameters monitored when problem occurs.

Thanks EnvoyBoy2004. Scan only came back with p0440, so I'm focusing on evap system first.
It over heats too, and thats when it at its weakest. Temp was around 215 and notice radiator boiling but Not blowing into reserve. So I'm gonna change radiator cap. Changed fuel filter about 2 months ago.
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Old 07-20-2019, 09:06 PM
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EnvoyBoy2004 EnvoyBoy2004 is offline
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I was not talking about reading codes, but rather live data such as fuel trims, O2 sensor performance. I would definitely look into checking out the catalytic converter.
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Old 07-20-2019, 09:13 PM
Monte27 Monte27 is offline
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Quote:
Originally Posted by EnvoyBoy2004 View Post
I was not talking about reading codes, but rather live data such as fuel trims, O2 sensor performance. I would definitely look into checking out the catalytic converter.
Thanks. I'll look into checking the cat converter also
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Old 07-21-2019, 10:41 AM
NJTB04 NJTB04 is offline
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Do you have any white smoke out of the exhaust?
215 degrees is not too hot on this platform. The bubbles in the radiator could be a problem.Is the overflow tank bubbling?
See if you can find one of those kits (sorry, I don't remember the name) that checks for exhaust in the radiator. If so, you may have a blown head gasket.
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Old 07-21-2019, 12:03 PM
Monte27 Monte27 is offline
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Quote:
Originally Posted by NJTB04 View Post
Do you have any white smoke out of the exhaust?
215 degrees is not too hot on this platform. The bubbles in the radiator could be a problem.Is the overflow tank bubbling?
See if you can find one of those kits (sorry, I don't remember the name) that checks for exhaust in the radiator. If so, you may have a blown head gasket.
Thanks NJTB04. No smoke from exhaust, and coolant wasnt blowing into reserve tank. Tried Not to think about head gasket yesterday. Gonna get a new radiator cap tomorrow and see what happens. Still trying to find out what, if anything in the evap system could or would cause the lack of power.
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  #8  
Old 07-24-2019, 07:03 PM
PalmBay04TB PalmBay04TB is offline
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My 04Tb with 220k miles had same probs, it was a plugged up cat convertor, was just clear enough to run but was running real hot and weak....put on new cat and its like a new truck again.
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Old 07-24-2019, 08:02 PM
RPatton76 RPatton76 is offline
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It is not likely an evap issue should affect power, especially if you're revving it much. When my other car cats died, the first one broke into small pieces and plugged up the 2nd cat and made power and mileage suffer and, though I didn't notice it, it was getting a quieter exhaust at the time. After changing cats, the exhaust sound came back to normal. Mileage was also going down at the time. If your problem is really that the motor gets too hot, I'd put in a new thermostat and maybe go down to the next lower temperature, and be sure to burp out any air that may cause overheating.

Rob in AZ
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Old 07-24-2019, 08:19 PM
Monte27 Monte27 is offline
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Quote:
Originally Posted by PalmBay04TB View Post
My 04Tb with 220k miles had same probs, it was a plugged up cat convertor, was just clear enough to run but was running real hot and weak....put on new cat and its like a new truck again.
Thanx. I'm still hopin its not that. Got only 160k miles on it. But your symptoms sounds like mine. Have a great day
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