Tonermaid

I am having woes with my Chevy 1500. The truck has a 5.0 with automatic transmission and 190,000 miles. Truck has many error codes such as P0118, P0125, P0141, P0154, P0172, P0175 and P0300. The plugs, wires, rotor, rotor cap, fuel filter, air filter and all four oxygen sensors have been replaced. At idle cylinders 3 and 7 have multiple misfires. Off idle to approx 1800 RPM only cylinders 4, 6 and 8 misfire. Over 1800RPM only cylinder 1 misfires. At idle or upon hard acceleration the engine exhausts a lot of black smoke. Several of the old spark plugs were fuel fouled. Fuel pressure at the manifold is 55lbs. The temperature sensors appear to be working properly. If I use any kind of injector cleaner the engine will die at idle and cough and sputter during acceleration and at highway speeds. Any help will be greatly appreciated.

golfer

You should go by the codes for troubleshooting because it sounds like you only had 1 ( for sure ) possibly 2 O2 sensors to replace.

If it's running rich it's usually due to the temp. sensor. If the temp sensor is not working properly the ECM thinks the engine's cold.

One of the codes you posted P0118 = engine coolant temperature circuit high input.

Another code P0125= insuffient coolant temperature for closed loop fuel control.

Based on those 2 codes I'm not sure how you can say " The temperature sensors appear to be working properly."

The codes P0172 = system too rich bank1 and P0175 = system too rich bank2 doesn't mean you had to change all the O2 sensors because as you know the truck is running rich.

The misfires could be caused by the truck running too rich but could also be a result of the ignition module and / or the pick up coil in the distributor.

kcb37

I think golfer has givin some good advice. The only thing I will add is that you should take your time and be sure you are changing parts that need changed. Problems like this usually get frustrating cause the first thing most people think of is the o2 sensor. I had mine running rich, it was plugs and wires. (not getting a full burn) So take a little time and try to have patience.
Good Luck