Thanks for reading. My 05 V8 SE has been skipping lately accompanied with a strong catalytic converter smell. My uncle owns a import repair shop here in town so we put it on his snap on reader and found that bank 1 and 2 were lean and there was a problem with the egr valve. So I pulled all the plugs, changed them as it had been running lean(the plugs were white.) Pulled the egr and cleaned it. Reassembled, still missing. Gonna try and pull the codes again to see what's going on. Any ideas as to the continued misfire? This was a sudden change to the engine as it had been running smooth and like a top.

 

There have been some on here that found the coilpacks had gone bad... don't know the codes they pulled though. Also, once you get the misfire figured out, the c.e.l. will most likely come on with p4070 codes for cat/o2 sensor issues. I have seen this with mine after doing a Seafoam treatment and also from the switch to winter gas... my c.e.l. went away after a couple weeks of driving as the cats burned off the contaminents.

 

Here this will explain why you have the smell. As the fuel burns, the organic sulfur compounds break down into simpler compounds. If the engine is running lean (more air than is needed to burn the fuel), the sulfur is likely to be SO2, or sulfur dioxide. The catalytic converter can change this into SO3 (sulfur trioxide), which then reacts with the catalyst to form sulfates on the catalyst. Over several minutes there is a build up of sulfates. If the engine suddenly starts to run rich (not enough air to burn all the fuel), such as when you stop at a red light, climb a steep hill, or brake hard to slow down, the chemistry changes. Now the sulfates are unstable and they react to form hydrogen sulfide, which is expelled from the exhaust pipe all at once. The high concentration is the reason for the bad smell! This effect is a common problem with new vehicles because the catalyst is working at a very high efficiency. However, as the catalyst gets older, the activity drops. Fortunately for us, one of the first reactions to be affected is the formation of hydrogen sulfide. So as the catalyst gets older, the smell will go away. It should also be noted that many catalysts never smell bad. One reason might be because the vehicle doesn't run lean for much of the time, or perhaps the catalyst has an extra component that reduces the production of hydrogen sulfide.

 

The maf sensor is one of the first places to look.

 

I have cleaned the sensor. But maybe there comes a time where they can't be cleaned? I'm still thinking the EGR is still stuck open..

 

Maybe, I would have the codes read again. What was the original EGR code? It may be that it needs to be replaced and a cleaning wouldn't help.

 

It's been awhile but I finally got to changing the EGR and fixed that problem. It was bad, the spring inside had broken and stuck open causing a vacuum leak. This in turn caused a lean condition that burned the plugs up. So, I changed all but the no.8 because of the bolt that holds the coil down is just turning in the head. Has anyone had this problem? Did you fix it? How?