Skip the auto shop - Our mechanics make house calls

Q: cold rough idle and P0303 code , run great after clearing code and warming up,

asked by on

Did timing chain job, new coil pack wires and plugs, clean up valve and new valve cover gasket, new exhaust manifold gasket, new IAC sensor, new tps, new fuel injector to cylinder 3, new air filter, oil change and filter change, new crank shaft sensor, new cam shaft sensor.

My car has 200000 miles.
My car has an automatic transmission.

A: Code P0303 suggests a misfire in cylinder #...

Code P0303 suggests a misfire in cylinder #3. This can happen for many reasons such as a vacuum leak, weak fuel pump (pressure), bad ignition coil, low voltage to the fuel injectors (causing pulse problems) or a faulty mass air flow sensor, all of which can cause an imbalance in the air/fuel charge in that cylinder. Try checking to see if you are able to replicate the misfire and see if it happens more under load or at idle or if it is completely just intermittent. This may help to narrow down what types of components to check.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: Not able to drive or reverse.

There could be broken linkage in the column/console, a broken shifter cable, a broken u-joint, or any of several other possible causes. A certified mechanic should be able to take a look at it and diagnose the problem, and if...

Q: 2002 Jeep Liberty Limited 3.7 misfire bent spark plug tip with rough idle

I can't find any information suggesting there is a recall for your vehicle. Either way, you need to figure out what has failed in cylinder number two. Replacing all the injectors is not going to fix the problem in cylinder...

Q: Car shut off when oil light came on, won't restart. What could it be?

Hello, What you are describing may be related to a safety switch that automatically causes the ECM to shut down the ignition to the engine when the oil pressure sensor reaches a certain level. This is the computer's way of...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.