Q: Performance restriction

asked by on March 06, 2018

Started with engine lights 171 and 174 found by WOW software. Slightly rough idle 4 last year. I replaced the upstream down stream oxygen sensors with an after market & found I was still having a problem up stream. Switched sides & discovered one of the sensors was bad after reading codes again. Bought 4 Denso U & D stream & installed. Decided to replace throttle Body & a new gasket to correct the rough idle of 200 rpm fluctuation. MAF sensor was carefully replaced new 7 months ago. Now I am getting a PO171 and a PO174 with a P1646 code reading along with a performance restriction light. At idle RPM it does not fluctuate at all. Seems strong & relatively smooth up to about 60 to 65 MPH & half throttle. Past half throttle it begins to shut down in a jerking behavior. Let up & at half throttle it drives good. Turned off codes 4 times & again last night & took it on the highway. Punched it 5 times + full throttle. Beautiful. Started it this morning-its back same codes & RP

My car has 91000 miles.
My car has an automatic transmission.

Based on the symptoms you’re having, I would recommend having your vehicle inspected by a qualified professional with a check engine light is on inspection. This will be able to determine the exact cause of this issue. Consider YourMechanic as this can be done at your home or office.

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