Random vacuum leak or bad fuel injector?

Rick

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Can you state what the three codes are that you listed above?

Usually intermittent issues like your describing can be caused by a bad ground connection. Start with your battery negative ground and ensure it is tight with no corrosion. From there follow the negative cables to where they attach to the engine and the frame/body and make sure those connections are tight with no corrosion.

 

I'm thinking bad ground(s) or corrosion as well. Make sure you peel back a little of the insulation on the negative cable so you can see the condition of the non-exposed strands. They have a tendency to corrode from within.

 

Sorry for the delay in response.
Codes are as follows:
P0171 - Bank 1 system too lean
P0131 - Bank 1 O2 sensor 1 faulty reading of voltage or air to fuel ratio.
P0152 - Bank 2 O2 sensor 1 fails to have a lower voltage output below 1.2 volts for more than 10 seconds indicating a lack of oxygen in the exhaust stream or a short to power in the sensor circuit.
P1174 - Fuel trim cylinder balance malfunction.
P0300 - Miss fire not related to one cylinder.

Thank y'all for the help this far. It hadn't crossed my mind that it could be a ground issue. I will check on that today once I am off of work.

Also Rick stated it could be an injector issue. Is it possible to remove the injectors and do a visual inspection? Or would it have to be broken down to really see an issue there?

 

I have had several injectors go high on impedance that caused a misfire when low. For my 5.3, the spec is 12 ohms impedance and my last one causing a misfire was at 68 ohms. It got replaced.

Not sure this helps you much . . . . ??

Rick

 

Update:

Made sure all exhaust manifold bolts were tight, checked for loose or corroded grounds and found none. Checked all injectors impedance and they all read 13 ohms.

I drove the truck around and I got a new code of p0430 Catalyst System Efficiency Below Threshold (Bank 2))...

 

It looks like it could be plugged catalytic converter on bank 1. Check the cat temps in and out, out should be a lot hotter from what I've read.

 

Hello All, I am new to the forum and I am having some issues with my truck. I've run low on options and figured this may help grant some valuable information.

(2008 Silverado 1500 5.3)

Recently I replaced my fuel pump/spark plugs/wires/ignition coils/catalytic converters (OEM)/ O2 sensors/MAF. I also installed shorty headers.

Prior to the install of the listed items above. The truck has a muffler and CAI.

The problem arose when I rented a small U-Haul trailer for some moving. I got on the highway and the truck lost power intermittently. The codes were p0171, p0300, p1174. My only option at the time was to take it to the dealership... needless to say they couldn't figure it out and didn't charge me for the 2 weeks they had it. They did recommend that it probably needed a tune since it now had short headers..... Next I brought it home and replaced the MAF since it seemed to idle better with it unplugged. Once replaced It ran perfectly with normal fuel trim until this morning when it lost power while cruising down the highway. I had to slow down due to power loss and made it to the 192.168.100.1 192.168.1.1 jpg to pdf nearest turn around. After driving for a few minutes being careful to not blow my motor, the truck spontaneously came alive and ran as if nothing ever happened for the rest of the couple minutes I was on the road. At this point I'm at a loss and am not sure what is wrong with it. Any help/advice would be nice. Thanks.

The short answer is yes, it could easily be the source of the issue. Having too much fuel pressure at the injector can cause an extreme rich condition. Too little can cause an extremely lean condition. Either of which will cause misfires. On another note: The existance of a MAP (Manifold Aboslute Pressure) sensor does not definitively prove you do not have a MAF (Mass Air Flow) sensor. Knowing other GM fuel injection systems from the era, you likely do (or at least should) have a MAF somewhere in the tubing between the air box and throttle body. Without the MAF your PCM will fall back into a mode referred to as speed density.