07 Silverado 5.3 classic hard to start rough idle.

[Adam Scott]

I have codes that it threw attached any help is appreciated thank you.

Edited July 27, 2019 by Adam Scott

[CamGTP]

The first two o2 sensor codes are heater resistance codes.

 

The MAF and MAP codes are both range/circuit codes and the misfire is well a misfire.

 

Being that 4 of those codes are wiring/electrical related I would be looking there first. Unplug the sensors, check for corrosion, check the connectors. Clean the MAF sensor with MAF cleaner. I would even look at the fuse box and check all the fuses related to the MAF and O2 sensors.

 

Remove and clean all known ground cables. So battery ground, the ground on the back of the drivers side cylinder head. I believe there is a ground from the engine block to the frame somewhere as well.

 

Visually check over the main engine harness. Look for possible damage and things like that.

 

Once you have the bases covered I'd clear the codes and see what comes back right away. The MAF/MAP codes along with the o2 sensor codes can make the engine misfire because it's not getting proper data back from them.

[Adam Scott]

This is my sons truck and he just dropped 1000$ because some jack leg said it was the cats. I am a mediocre mechanic but am somewhat mechanically inclined. So I understand the people I took it to supposedly changed out the MAF sensor with no change. I’m not sure what MAP means. Thank you

[Jstevens7700]

All of these codes have one thing in common: fuel. I had the exact same problem on my 2005 gmc Sierra 1500 and it took me about a year to figure out that the fuel pump wasn't getting the correct psi. Very frustrating especially after cleaning grounds, new plugs wires and coils, a gas pedal sensor and a throttle position sensor and still no change. Fuel pump is the problem in my opinion but if you want to make sure use a fuel pressure tester and test the psi on the fuel rail. It should be around 60 idling. It should drop during acceleration briefly then come back to 60. Mine was staying at 30 regardless. Best bet is get a fuel pump make sure it is the correct pump for your bed size and it should resume normal operation.

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[CamGTP]

If you payed for a repair that was suppose to fix the problem, then take it back and make them fix it or get your money back. That is just shotty work if they can't even properly diagnose the problem.

 

MAP stands for Manifold Absolute Pressure sensor.

 

Like I said, all those codes point towards a some sort of electrical issue strictly based on the codes description.

 

 

Edited July 27, 2019 by CamGTP

[Colossus]

By the time 200,000 miles rolls around, the cats and O2 sensors on many vehicles are going to be pretty tired Even 150,000 miles on some, especially if you run crappy cheap non top-tier fuels. 

[davester]

Yes, check fuel pressure (both at idle, and with the engine revved up), should be right around 60 psi for both.

 

Also check that all the exhaust manifold bolts are present (they are prone to breaking off with the 6.0, IDK if it's also a problem with the 5.3).

[diyer2]

Sounds like the work paid for was done by a mediocre mechanic. Happens a lot.

I'd stay away from that shop. I agree I would have a talk with them.

In the future when a check engine light comes on take your vehicle to any auto store. They  will read the codes for free.

Google the codes.

When a problem arises with something I own and I don't know how to fix it I always turn to Google.

At the least you'll learn something that can be helpful.

 

Do the things you can do like checking the electrical as mentioned. Be thorough because the vehicles today require proper voltages to run right.

Check fuel pressure. I think a fuel pressure gauge can be bought at Harbor Freight for $35. 

Google how to test the fuel pressure.

 

Good Luck

 

[sefiroxx]

My idle speed and hard start problems occurred twice
- fuel pump
- isc valve