2000 Blazer 4.3 was running rough. Service engine light was on and checked DTC's and had a P0300 misfire and no other codes. I know there are issues with these with the misfire DTC. I hook up a timing light and seem had a misfire in cylinder #2. Started her up and she was running really rough and smoking with white smoke but the smell of fuel. Like she is running really rich. So I replace the wires, plugs, cap and rotor and now she won't start at all. Any suggestions?

 

What did the old plugs look like?

Are you double sure the plug wires are in the correct place?

 

Plugs looked fooled ( black ) and smelled like varnished gas. This is a daily driver and recently started running rough. I doubled checked all plug wires and all are good. She cranks over and seems like she just about to start but not luck. There is a prominent gas smell. After I changed the plugs on the passenger side I started her up and was still running rough. After I changed the driver's side she wouldn't start. I'll pull the plug wires and check for bad plug wires and make sure they are secure. Also, I forgot I got the following DTC's besides P0300 - Random Misfire Detected.

P0143 - O2 Circuit Low Voltage ( Bank 1, Sensor 3 )

P0172 - System too rich ( Bank 1 )

P0175 - System too rich ( Bank 2 )

I suspect a bad O2 sensor which is causing her to run rich. Which could be the reason of the gas smell.

 

I had plug wires 1 and 3 reversed. No big deal, fixed that and she started right up. I'm still getting the dreaded P0300. Cleared the DTC's and it came right back. Checked all vacuum lines and they look good. How do I check for the possible injector issue?

 

Nice job on the wires

The B1S3 O2 sensor is the one after the cat I'm pretty sure. This is getting beyond my knowledge without looking stuff up. With it running so rich, I am worried about the cat having issues. I'm not saying the cat is the cause of the 0300 code ( yet anyway ). There is a good thread about running through the possible causes of the 0300 code on here, I forget the name of it though....

I will see if I can find it after soccer. Hopefully the really knowledgable people will have given their two cents by then too!!


Well I see no one else chimed in, so I will just edit my post with some links. Check these out for now....

https://blazerforum.com/forum/2nd-ge...ng-post-13501/

https://blazerforum.com/forum/diagno...4-5-6-a-35153/

 

Fuel pressure leak down test. See sticky. O2 sensors may be carboned up but they are not the cause of running rich to the point of a misfire.