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07-21-2013, 11:59 AM #1
- Join Date
- Jan 2009
P0300 Rough Idle ideas? 2004 Z71 5.3
Ok as I posted last week I bought a 216k Mile 2004 5.3L Z71.
I knew the cig lighter dident work (dident really care) but the truck was idleing slightly rough this I also knew, but their was no CEL. Running it today a CEL came on, put my basic reader on and no power, goggled and found that a blown cig fuse can cause no power to the reader connection and it worked, ran it and got a p0300.
Now the previous original owner "thinks" he had half or all the plugs changed at about 150k when he had a cracked head replaced but not sure. I have that "need a tune up smell" from the exhaust not completely rich smelling just that incomplete combustion smell. Air filter is clean, I just cleaned MAF nothing.
So my first step is plugs I ordered NGK IZTR5B11 Laser Iridium That are pre gapped .40. Should I use these? Return and get AC Delco Platinum? Iridium? Should I go with wires or see if plugs?
Other things I have read clean the flapper on the TB (wifes Mazda 3 would run rough after pulling battery due to carbon build up) and pull and clean or replace IAC Valve.
Any other quick cheap fixes before I get too deep into digging?
- - - Updated - - -
Scratch that put the NGKs In and AC Delco 9748HH wires I got from Advanced Auto and all is well running great under throttle and idle is butter smooth.
Stock plugs were the worst I have ever seen! They look every bit of 216k miles.........
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ALSO cleaned TB while I was their
07-26-2013, 09:03 AM #2
2009 Chevrolet Silverado 1500 LT Z71 Crew Cab "All-Star Edition"
Line-X'd Custom Brush Guard(Heavy Duty)
5.3L Flex Fuel
Factory Black Running Boards
BF Goodrich All-Terrain KO's(265/65R18)
2" Rough Country Leveling Kit
EGR In-Channel Vent Visors
Exterior PLUS Package
Interior PLUS Package
K&N Drop-In Air Filter
Bowtie Mud Flaps
Cat-Back Dual Exhaust
Diablo Sport Predator(AFM Disabled)
Next Planned Mods
07-26-2013, 01:09 PM #3
you can do the whole seafoam thing and see if that helps any.
Have you changed the fuel filter yet?2000 Silverado 5.3L Z71 4x4: K&N air filter:great:
07-26-2013, 01:59 PM #4
IMO, the steps you do when buying a used vehicle:
Change rotor and distributor cap(if equipped).
Change plugs, and if the vehicle has high mileage, change the wires.
Change oil and filter.
Lube job(if you can).
Change transmission fluid.
Change differential and transfer case fluid if equipped.
Coolant system flush.
Change air filter(K&N).
Change serpentine belt.
Change brake fluid.
Change fuel filter.
Run a bottle of fuel injector cleaner in the fuel tank(gas engines).
Get AC refrigerant levels checked.
Change cabin air filter.
Clean throttle body.
Inspect tires for wear and have alignment checked.
Change power steering fluid.
Inspect rubber hoses for possible leaks.
I know this seems like a lot, but unless I knew the previous owner and was sure they stayed on top of the required maintenance, I would feel better having these things done.
2013 Silverado LTZ White Diamond Crew Cab
Advent OGM1 Navigation
Husky Liners GearBox Underseat Storage
EGR Rail Caps
K&N Air Filter
Flowsound 40 Muffler
Hypertech Max Energy Tune (only top end limiter removed and AFM disabled)
Chrome Tailgate Handle Cover
TonnoPro HF-155 Tonneau Cover
WeatherTech Front and Rear Splash Guards
Husky Liners X-Act Contour Floor Liners
WeatherTech Side Window Deflectors
07-26-2013, 05:20 PM #5
I would use the ac delco irridium plugs. you do not adjust the gap. if you do you will damage the small tip. if the gap looks off the plug is defective !
before replacing any plug wires measure the resistance. many new wires are defective with POOR quality control.