Q: Performance restriction

asked by on

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.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Performance restriction

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Coolant leak.

A cooling system pressure test using dedicated equipment will be able to pinpoint the location of your coolant leak. Running a vehicle low on coolant can cause it to overheat, resulting in extensive engine damage. My best advise is to...

Q: 2004.5 Volvo S40 T5 alternator

These vehicles are known to have issues with aftermarket alternators since they are computer controlled charge circuits and aftermarket alternators do not always work correctly and only dealer alternators will work correctly.

Q: Fuel light flashes, check engine light on

Hi there, thanks for writing in about your 1997 Mercedes-Benz S420. The fuel light circuit receives information from the fuel level sending unit to show the approximate fuel level and give a warning as the level becomes low. There can...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...