Q: Rough idle on acceleration displaying symptoms of a misfire, but there is no misfire codes detected. On cold starts the car is completely normal.

asked by on

Make: Pontiac Year: 1996 Model: Firebird Drivetrain: 5.7L LT1 V8/4l60 A4 trans Modifications: Pace setter long tube headers/ORY, SLP LM1 exhaust(No cats)

OBDII Codes: P0134 P0134 02 Sensor Circuit No Activity Detected (Bank I Sensor 1) P0141 P0141 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2) P0154 P0154 02 Sensor Circuit No Activity Detected (Bank 2 Sensor 1) P0400 P0400 Exhaust Gas Recirculation Flow Malfunction P0443 Evaporative Emission Control System Purge Control Valve Circuit P1441 EVAP System Flow During Non-Purge Condition

Problem: Rough idle/acceleration displaying symptoms of a misfire but no misfire codes located

When is problem notice?: When car is at operating temperature, during full RPM range(I haven't yet tried wide open throttle to test for O2's) On cold starts car is completely normal

What have you already tried?(Will edit as suggestions come): Checked and cleaned EGR, Checked all vacuum lines for any leaks, checked for exhaust leaks(repaired 2), checke

My car has 153456 miles.
My car has an automatic transmission.

Hi there. Since you have a code for the Exhaust Gas Recirculation (EGR), the EGR could act like a vacuum leak and cause a random misfire. Remove the EGR and clean it out and then put it back on. If the symptom gets better but the engine still has a misfire, then I recommend replacing the EGR valve. The EGR valve will cause the O2 sensors to register to the computer and set a code for the O2 sensors. This is normal for the O2 sensors to work. For the EVAP issue, check the gas cap and make sure that the seal is good. Also, check the purge valve on the fuel system and see if its plugged in. Most of the time the valve gets stuck and needs replaced. If you need further assistance with your engine having a misfire, then seek out a professional, such as one from Your Mechanic, to help you.

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. Rough idle on acceleration displaying symptoms of a misfire, but there is no misfire codes detected. On cold starts the car is completely normal.

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: I have a 2012 ram 1500. From a stop at a light or stop sign when i give it gas i feel and hear a grinding sound from the pedal.

It sounds like you may have a problem with the traction control system, which may include a number of things. The traction control system monitors the steering and stability of the vehicle and engages when loss of traction has been...

Q: Q: Misfiring cylinder

When the on-board diagnostic system picks out specific cylinders for misfires, the ignition and fuel delivery systems must be inspected. A misfire on a single cylinder may involve the spark plug or fuel injector related to that cylinder. In the...

Q: Ruined ECM

Hello. If your issue is a ruined ECM, then it is likely that the ECM merely failed, or that a wiring issue caused it. Code 12 indicates that the computer is ready to communicate codes to you. If no codes...

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...
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 to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...