P0172 95 4.3 vortec running rich need help
September 10th, 2018, 9:26 PM
#1
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P0172 95 4.3 vortec running rich need help
Have done everything possible to solve this problem. I am simply baffled and I'm a certified Diesel mechanic. The P0172 code keeps coming back.
checked fuel pressures - good
checked fuel regulator - no leaks functions well
removed upper plenum - found no leaks, while i was in there i also checked poppets for leaks, CFI spider for leaks- its a new unit and all o-rings are good and sealing. Also replaced the main fuel hoses with CFI replacement. no fuel leaks anywhere in or out of plenum. Also tried swapping CFI injector with known good injector just in-case the new injector was bad.
checked and repaired all vacuum leaks.
isolated plenum from all vacuum sources (except brake booster for safety reasons - but verified booster is sound and sealed)
checked map sensor - tests all good
checked TPS - tests good no dead spots
checked O2 senors - all good - replaced upstream sensor to be sure.
Pulled and checked spark plugs - all are dry and not fuel fouled - dry light brown coloring - verified gap
replaced rotor and cap and wires.
also replaced plenum gaskets
The catalytic converter is now failing due to engine running rich for too long but was not the cause of running rich condition.
checked fuel pressures - good
checked fuel regulator - no leaks functions well
removed upper plenum - found no leaks, while i was in there i also checked poppets for leaks, CFI spider for leaks- its a new unit and all o-rings are good and sealing. Also replaced the main fuel hoses with CFI replacement. no fuel leaks anywhere in or out of plenum. Also tried swapping CFI injector with known good injector just in-case the new injector was bad.
checked and repaired all vacuum leaks.
isolated plenum from all vacuum sources (except brake booster for safety reasons - but verified booster is sound and sealed)
checked map sensor - tests all good
checked TPS - tests good no dead spots
checked O2 senors - all good - replaced upstream sensor to be sure.
Pulled and checked spark plugs - all are dry and not fuel fouled - dry light brown coloring - verified gap
replaced rotor and cap and wires.
also replaced plenum gaskets
The catalytic converter is now failing due to engine running rich for too long but was not the cause of running rich condition.
Last edited by 970joe; September 10th, 2018 at 9:50 PM.
September 11th, 2018, 12:46 AM
#2
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Have done everything possible to solve this problem. I am simply baffled and I'm a certified Diesel mechanic. The P0172 code keeps coming back.
checked fuel pressures - good
checked fuel regulator - no leaks functions well
removed upper plenum - found no leaks, while i was in there i also checked poppets for leaks, CFI spider for leaks- its a new unit and all o-rings are good and sealing. Also replaced the main fuel hoses with CFI replacement. no fuel leaks anywhere in or out of plenum. Also tried swapping CFI injector with known good injector just in-case the new injector was bad.
checked and repaired all vacuum leaks.
isolated plenum from all vacuum sources (except brake booster for safety reasons - but verified booster is sound and sealed)
checked map sensor - tests all good
checked TPS - tests good no dead spots
checked O2 senors - all good - replaced upstream sensor to be sure.
Pulled and checked spark plugs - all are dry and not fuel fouled - dry light brown coloring - verified gap
replaced rotor and cap and wires.
also replaced plenum gaskets
The catalytic converter is now failing due to engine running rich for too long but was not the cause of running rich condition.
checked fuel pressures - good
checked fuel regulator - no leaks functions well
removed upper plenum - found no leaks, while i was in there i also checked poppets for leaks, CFI spider for leaks- its a new unit and all o-rings are good and sealing. Also replaced the main fuel hoses with CFI replacement. no fuel leaks anywhere in or out of plenum. Also tried swapping CFI injector with known good injector just in-case the new injector was bad.
checked and repaired all vacuum leaks.
isolated plenum from all vacuum sources (except brake booster for safety reasons - but verified booster is sound and sealed)
checked map sensor - tests all good
checked TPS - tests good no dead spots
checked O2 senors - all good - replaced upstream sensor to be sure.
Pulled and checked spark plugs - all are dry and not fuel fouled - dry light brown coloring - verified gap
replaced rotor and cap and wires.
also replaced plenum gaskets
The catalytic converter is now failing due to engine running rich for too long but was not the cause of running rich condition.
September 11th, 2018, 8:51 PM
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Yes I have a scanner and both fuel trims are in the negative. This specific truck has an OEM Y-tube exhaust pre cat and only utilizes 1 pre / 1 post cat sensor. Yes the engine temp is above *195 F.
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September 11th, 2018, 10:13 PM
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-21.5 cylinder #1 but the engine in my truck doesn’t have an adjustable distributor. Tried that route already. It goes in. Locks in place and doesn’t have any timing marks in the front of the enigine. It uses pulse width timing.
September 11th, 2018, 10:17 PM
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Yes still low at idle. My next steps are to buy bosh 02 sensors and replace both. Also to check the operation of my EGR. What I have noticed is the long term fuel trim when driving at cruising speed goes to -18 and stays there. It does fluctuate when accelerating and deceleration but stays constant when cruising.
