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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2006 - 2009 TrailBlazer SS Tech > 06-09 SS Engine and Drivetrain > OEM Issues

OEM Issues Original Equipment Repairs/Problems

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Old 05-09-2019, 10:31 PM
Luiso39 Luiso39 is offline
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Join Date: May 2019
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I have an 08 TB LT with code p0300 I have changed spark plugs, clean throttle body put like 2 cans of injector cleaner check injectors check for vacuum leaks I also put 3 can of the valve cleaner check the timing the truck runs good on highway but when I stop at a lite or idle it start shaking not like if it want to turn off but just a rough idle what am I forgetting to check?? Pls help it only have 85000 Miles on it need help pls and thank u
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Old 05-10-2019, 05:15 AM
Jewel red 5 Jewel red 5 is offline
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2007 GMC Envoy Denali
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Shot in the dark but found this on the web good luckhttps://www.youtube.com/watch?v=vIsJo7Z6vhE
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Old 05-15-2019, 08:10 PM
04Blue42 04Blue42 is offline
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Had the same problem... Ended up being a bad coil.sounds like a misfire
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Old 05-16-2019, 02:55 AM
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rcott01 rcott01 is offline
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2004 GMC Envoy SLT XL
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Could be a motor mount also. When they get smashed it can cause all kinds of weird things to happen
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Old 05-16-2019, 08:31 AM
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Grinder Grinder is online now
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2004 Chevy TrailBlazer LT
Indigo Blue Metallic 4.2L I6 4X4
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The P0300 code is a random misfire code while all the other misfire codes (P0301 - P0306 )denote a misfire problem in a specific cylinder.
A Random P0300 Misfire code often indicates a vacuum leak or bad gas.
Check for a bad vacuum line leaking ( upsetting the fuel mixture ) or a bad batch of (water / contamination in it ?) fuel....
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