Hi, new guy here, can someone help!
Hi, I have a 2004 Chevy Suburban "Z" 8th digit 5.3l .215,000 miles. Engine was running terrible and misfiring. Got the p0300 random misfire code. I used a timing light to check which cylinder was missing. I determined that the whole passenger side was missing. I changed out both o2 sensors on that side. and my problem was gone. I never reset the codes. I just drove it. Engine ran great. Check engine light turned itself off. That same day. I took it through for my state emissions test and passed with no problems. Engine ran great for 2 days.
On the 4th day after replacing the 02 sensors, I was driving home from work and suddenly with no warning at all, complete loss of power and smoke from high heat coming from my catalytic converters. Both were glowing at the front telling me un burnt fuel collected in there. Engine would not restart.
The following morning after completely cooling off it still would not start. Had it towed to the house. Pulled the codes and there was the p0300 code again, and a lean condition code in bank 2. Forgot the code for that off of the top of my head. Seems like there is no spark at all though. I pulled plugs from both sides and are wet with fuel. Fuel pump and filter are new (10,000) miles ago. No fuel in pressure regulator hose and there is plenty of pressure at the test fitting.
I sprayed throttle body cleaner into the intake to determine if engine would fire up. It did not. So I am kinda at a loss as to what happened, and where I should go from here. Crank sensor? Would a failing crank sensor allow fuel into the exhaust system?
I'm borrowing my mother in laws hyundai and I want to give it back MORE than she wants her car back! Thanks for reading and helping!

Surprised you passed inspection, if you didn't clear your codes.....

"I sprayed throttle body cleaner into the intake to determine if engine would fire up. It did not. So I am kinda at a loss as to what happened, and where I should go from here. Crank sensor? Would a failing crank sensor allow fuel into the exhaust system? "

Obviously you have no spark....your plugs get wet because there is no spark....and that un-burnt fuel reached the cats......

If you have access to a good scan tool, diagnosis is easier.....

Assuming you don't, you can do some basics......first check for power....the injector fuses power the coils...#1 inj fuse for the odd numbered coils, and #2 inj fuse for the even numbered coils....

just disconnect the harness at each coil,,,,,A is ground....B is low ref......C is control.....D is battery....

So do this test on one even and one odd numbered coil.....with key on, attach test light to disconnected harness at terminals A and D....this verifies power and ground, test light should light......now attach test light C to D, and crank vehicle...should flash....check coil on opposite side to see if it flashes.....if it doesn't, either bad crank sensor or PCM.....

Hi thanks for your reply!

I too am surprised that it went right through NJ inspection. Strange series of events to this point.

I do have a quality scanner at hand. My friend lent me his snap on solus edge. But, I am not well versed on all of the tests that it can perform. My truck has a whole bunch of codes present... p0135 p0141 p0154 p0161 p0174 p0300 p0446 p0453 I'm thinking that the 02 sensor codes and the p0174 were thrown as the engine was dying, but I'm not sure.

I will try the test light on the coil packs and post my results here. Thanks for your help!

Brian

Ok, so there is no spark. I tested coils on both sides of the engine with a spark tester.. I did a power check to the coils. I have power being supplied to the coil. I probed the power circuit with a test light to the neg battery terminal. I also checked both grounds to the coil. I have a solid chassis ground, and also a solid ground through the pcm. I guess my next test should be if I am getting coil pulses from the pcm. I need a wire piercing tool to do this and I don't have one. Going to see if I can find one somewhere. I'll be back. Thanks

Can I do this test with the connector off of the coil? If so, I wont need a wire piercing tool.

I saw a test on easyautodiagnostics.com and told me to probe the pulse circuit with a multi meter set to hertz. Probe pulse circuit with connector on coil and use a wire piercing tool. Connect red lead to pulse circuit and black to negative battery terminal. Crank engine. Should read 5-8 hertz.

Any thoughts here?

Harness disconnected, attach test light between C and D.....crank vehicle and the light should flash.....

Sorry that I kind of abandoned this thread! I have been a busy beaver!

So, I tested the coils with the hertz setting on my micrometer. I got 9 Hertz. When I used the test light test as mentioned above, the test light didn't flash. This really confused me! I was like WTF! Ok, so my thoughts were that the crank sensor went bad and I am just going to go ahead an get one and hope for the best. The only thing that I didn't check were the multiple grounds to the chassis. I got under the truck and the very first ground that I checked was the main ground from the battery. Negative battery end looked nice and clean. I followed the main ground to the engine block on the drivers side. I stuck my hand up there and peeled back some of the plastic protector so I could get a look. Looked ok. A little discolored, but not bad. I noticed a smaller ground wire coming from the wire harness that is connected to the block underneath that battery ground. I just touched it and it broke off in my hand. I thought that it was unlikely that this miniature ground wire would cause my no start issue, but before I go any further, I figured that I need to clean it up and replace the end. $1.00 for the wire end and 10 minutes to fix it, I put the key into the ignition, and music to my ears! She started right up! Wow! I was kind of in shock. I cleared all codes and drove it around on short trips for a few days with no problems. So I am going to close the book on this problem and hopefully if someone else has this same issue, check your grounds!