Hello out there.
I Need expert advice and knowledge. Had misfire cyl 4 code and two O2 sensor codes simultaneously. Raw gas dripping heavily out tailpipe. Checked plug. Looked well worn. Replaced with new plugs, Accel cap & rotor, premium wires. Still had misfire but the parts were ten years old so they needed replacing. Research showed fuel pressure regulators to be a common problem on 4.3s. Tore down to access csfi system. Removed and checked regulator with a vacuum pump. No leaks. Reinstalled csfi unit and with plenum still removed powered up fuel system to observe unit. No 4 would not stop spraying. Found out csfi units are problematic with those poorly designed poppets. Opted to upgrade to mfi system. After reassembly with new mfi unit truck still misses and drips raw gas from tailpipe! Suprised me, as I know the old unit was faulty. Fuel pressure is good and system holds the pressure with key off without bleeding down with the new mfi unit. My question is; Can a misfire from a bad injector or poppet causing a wet fouling condition of plug lead to a toasted ecm with the ecm only dropping that cylinder? I believe the ecm has a power module for each cylinder if I am not mistaken. I had no code for a bad ecm. The codes for the O2 sensors I disregarded as symptoms from the raw gas and hope they're still in good shape after getting 2mpg for about 8 miles. Truck has only 68k original miles. If it's not the ecm, what might the problem be? And if it is the ecm, what's involved with flash programming a new unit? Thanks for any knowledgeable replies.
I Need expert advice and knowledge. Had misfire cyl 4 code and two O2 sensor codes simultaneously. Raw gas dripping heavily out tailpipe. Checked plug. Looked well worn. Replaced with new plugs, Accel cap & rotor, premium wires. Still had misfire but the parts were ten years old so they needed replacing. Research showed fuel pressure regulators to be a common problem on 4.3s. Tore down to access csfi system. Removed and checked regulator with a vacuum pump. No leaks. Reinstalled csfi unit and with plenum still removed powered up fuel system to observe unit. No 4 would not stop spraying. Found out csfi units are problematic with those poorly designed poppets. Opted to upgrade to mfi system. After reassembly with new mfi unit truck still misses and drips raw gas from tailpipe! Suprised me, as I know the old unit was faulty. Fuel pressure is good and system holds the pressure with key off without bleeding down with the new mfi unit. My question is; Can a misfire from a bad injector or poppet causing a wet fouling condition of plug lead to a toasted ecm with the ecm only dropping that cylinder? I believe the ecm has a power module for each cylinder if I am not mistaken. I had no code for a bad ecm. The codes for the O2 sensors I disregarded as symptoms from the raw gas and hope they're still in good shape after getting 2mpg for about 8 miles. Truck has only 68k original miles. If it's not the ecm, what might the problem be? And if it is the ecm, what's involved with flash programming a new unit? Thanks for any knowledgeable replies.
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