Q: Rough start/idle plus loss of power

asked by on

The car is experiencing hard start only when it's cold and from time to time it had rough idle which gets rougher when the car is in gear. I've replaced fuel and air filters. Also car has loss of power when I punch it. I ran diagnostics and the car. Some back with whole bunch of codes for miss fires P0300-P0306, fuel pressure regulator performance P2293. I might also add I'm terrible at maintaining the car and have a oil leak :(((

My car has 125000 miles.
My car has an automatic transmission.

Hi There, This is an indication of a fuel pressure problem as indicated by the codes you have pulled. The fuel pressure regulator is a device which controls the pressure of fuel supplied to the fuel injectors on an engine. This works by bleeding off a portion of the fuel flow to the injectors from the fuel pump to control the fuel pressure. Fuel is pumped from the fuel tank to the fuel rail by the fuel pump. The fuel pressure regulator is normally mounted after the fuel rail to ensure that the fuel rail has priority in fuel flow. The valve in the regulator controls the amount of fuel that is bled from the fuel rail by opening an outlet port to allow fuel to flow back into the fuel tank. All injectors need a pressure difference between the inlet and the outlet of the injector to spray fuel into the combustion chamber. This is called the base pressure. The base pressure is adjusted via the adjustment screw to suit the injectors and specific fuel pump system you are using. The adjustment screw pushes down on a spring which applies a force onto the valve. When the pressure inside the bottom chamber of the regulator exerts a high enough force on the valve to overcome the spring force and lift the valve off its seat, it allows fuel to flow through the outlet port effectively controlling the fuel pressure in the fuel rail. Since the outlet of the injector is exposed to manifold vacuum/pressure which varies depending on throttle movement, but the flow of fuel from the fuel pump is constant, the valve needs a reference to continuously change the amount of fuel bled to maintain constant fuel pressure to the injectors. I would suggest having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
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. Rough start/idle plus loss of power

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: Rattling Sound - 2007 Subaru Impreza

Hey there. I suspect you have an engine-mounted bracket that is touching a heat-shield or other metal component under the hood, generating the noise you hear. Get a helper to hold the brake, and put the car in gear while...

Q: 2004 jag xj8 4.2 v8 auto trans 5spd had trans fluid leak. lost approx 6qts. repaired leak and filled per instructions on alldata w

The two codes, P0736 and P0730 overlap to some extent insofar as possible faults. If the transmission fluid got really low, the transmission might have overheated with several consequences: burnt fluid; mechanical damage, case/part distortion, damage to hydraulic seals on...

Q: My car will crank and doesn't start - delayed in the AC

Your Audi is known for having timing chain issues. This is the first thing I would suspect. The timing chain tensioners fail and the chain will jump teeth and damage valves. At the very least you will need the timing...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.