Q: Codes p0171/p0300 came up after intake manifold repair, car feels like it’s bogging down/ not getting enough air! Idk what to do ?

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Got a Intake manifold repair, next day check engine light came on , code reader stated p0171 and p0300 , i checked the codes again then it stated intake manifold. i changed spark plugs and wires, Pcv valve, egr valve before repair, now when idling the oil gauge fluctuates below 40 then above to 60, the car jumps and seems to not be getting enough air ! couple times while driving the car jerk when shifting gears but shift very smooth, think I’m due for transmission flush, also when i accelerate and go about 50 to 60 mph the car shakes , after 60 it returns to normal, it has no problems starting up

My car has 150000 miles.
My car has an automatic transmission.

The cause behind diagnostic trouble code P0171 is easiest to find by looking at the secondary firing patterns on the bank one cylinders. That will confirm if the too lean condition, that has caused code P0171 to set, affects all cylinders in the bank. If not all cylinders are affected, test for defective individual fuel injectors. However, if all cylinders are affected, you would test, in turn: the fuel pressure regulator, fuel pump pressure, check for a clogged fuel filter, vacuum leak, faulty oxygen sensor(s) and faulty mass air flow sensor. Rarely, the cause will be a faulty powertrain control module. If you want the required diagnostic steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a check engine light diagnostic - code P0171 and the responding certified mechanic will get this taken care of for you.


With regard to the apparent fluctuation in oil pressure, if engine speed is constant while the pressure fluctuates on the gauge, the gauge, or gauge circuit, is probably faulty. Oil pressure will fluctuate but the fluctuation should be in step with changes in engine speed. The vehicle vibration at speed could be due to anything from faulty motor mounts, engine mis-operation under load, or faults with wheel balance and/or the suspension system. The cause would have to be pinned down during a hands-on inspection and test drive. What I would suggest is resolve the trouble codes first through a check engine light diagnostic - code P0171 which of course will aid in ruling out engine misoperation as a possible cause of the vibration. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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