2011 Silverado 3500HD dually 6.0 gas ,no flex fuel

scott willman · February 5, 2020

Okay I have a random misfire code 300 302 304 307 replaced already o2 bank 1 upstream and down stream,new plugs,new wires,new coils, new injectors,maf and map, truck will idle fine then it won’t,check engine light will blink and then stay on,if it’s idling ruff and I take off it stumbles till I hit 25 or 30 mph and then I punch it and it runs fine for an hour down the freeway, then when I stop it may idle ruff or fine what is going on with this truck and it has a lot of power,help......gas engine no flex fuel

Edited February 5, 2020 by scott willman

tlaw91 · February 6, 2020

How knowledgeable are you with vehicles? Do you have a lot of equipment?

You’re dealing with two misfires on one bank and one misfire on another bank. This has narrowed it down some.

I need to know what your fuel trim is, short and long term, when this happens.

-GM Tech

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scott willman · February 6, 2020

I just have a basic Bosh obd 2 it doesn’t show fuel trim just codes; what would a decent bidirectional scan tool cost me and do you know a good brand,as far as me I did the work I listed and I’m very mechanical, just no scan tool,going to have to get one,truck only has 118,000 on it mostly hiway miles

Edited February 6, 2020 by scott willman

tlaw91 · February 6, 2020

If you want to fix this correctly you are going to need a scan tool. You cannot keep guessing here as it’s wasting your time and money. Also most of those parts you put on never go bad, you should’ve posted on here earlier!

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tlaw91 · February 6, 2020

Also as of the scan tool I use GM GDS software with GM software and hardware to connect to vehicles I don’t mess around with aftermarket scanners.

I’m sure they work great I just have no need to use/try them.

I’m sure some DIY-ers on here can direct you to a scan tool that’s reasonably priced and works for your needs.

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