p0172 p0175 now p0306

skidoomankemp · Jan 21, 2015

After fuel pump was changed codes po172 and po 175 came on. Rich bank 1 and bank 2. After awhile I got po302 misfire cylinder 2. Po 172 and po175 did not show up. Changed plugs, broke clip on cylinder 6. Was getting po300, multiple misfires. Got used wire and changed 6, went back to po302 misfire on 2. Changed wire on 2 and still the same. Changed cap and rotor and no codes but hesitation. This am code po306, misfire on 6 and po172 and po175. Fuel pressure is 55 key on, 75 truck running and back to 55 truck off. After 1.5 hours it dropped to 55. Appreciate all help.

08chevy66 · Jan 22, 2015

Start with changing the wires. Don't use used ones cause that could cause more issues

skidoomankemp · Jan 22, 2015

I am pointing towards bad wire for misfire on cylinder 6. The po172, po175 are I think my real problem. Maybe regulator since I think 75psi is too high?

08chevy66 · Jan 22, 2015

Start with the misfire. A misfire can cause rich codes. After the misfire is fixed then look into the rich codes. 75 does seem too high so you could be right on the regulator but have to start with the misfire first.

corker · Jan 22, 2015

Agree with 08chevy66, you are showing rich codes on both banks so you have multiple misfires. Fix the misfires first and rich codes will go away. First ensure the ignition system is in good shape - plugs, wires, cap, rotor, coil and associated wiring. Then move on to fuel system.
Corky

p0172 p0175 now p0306

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