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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. |
Originally Posted by 970joe
(Post 362469)
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. |
Is the engine temp ok?195,cooler will run rich
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The 95 is a 2 upfront o2 sensor?swap them,side to side, just thinking other 02 is not up to par
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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. |
https://cimg6.ibsrv.net/gimg/chevrol...9dabc8962d.png
https://cimg7.ibsrv.net/gimg/chevrol...433cbe33c3.png https://cimg8.ibsrv.net/gimg/chevrol...f58f97559a.png These are the last freeze frames from when the code has shown up. P0172. |
Yikes,where's the timing at?
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And ft's at idle,still low?
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https://cimg7.ibsrv.net/gimg/chevrol...1d31572230.png
-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. |
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. |
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