Skip the auto shop - Our mechanics make house calls

Q: Misfire wont go away

asked by on

Problem started with misfire codes on cylinder 8, then cylinder 5, then random misfire. Did full tune up, replaced iac, cleaned fuel tank, changed fuel pump and filter, had vaccuum and compression test done. Checked cat and oxygen sensors. Replaced injectors with 4 hole 21lbs, cleaned fuel rail, ran great for 130 miles. Now is even worse, stumbles, no engine light but stored codes say random misfire, plus misfire on all 8 cylinders. At a loss on what to check next.

My car has 188000 miles.
My car has an automatic transmission.

A: Hi there. From your description of all that...

Hi there. From your description of all that has been done. I suspect you may have a computer problem. The powertrain control module (PCM) is designed to store a fault code in pending codes, on the first drive cycle that it recognizes a malfunction. If, on the second drive cycle, the PCM recognizes the same malfunction, the check engine light should come on and stay illuminated. The check engine light typically flashes during misfires detected. This may also be a connection problem at the PCM. Programming may also be an issue. Try disconnecting the negative terminal of the battery. Disconnect and inspect the electrical connector(s) at the PCM for signs of corrosion or loose terminals. Repair as necessary. Reattach connector(s) and reconnect negative battery terminal. The computer will have a period of relearn, idle speed, etc. This should happen with a short road test. Something else to look at would be the ignition coil(s) output. If you are unable to resolve the misfire(s), a certified YourMechanic technician can come to your location and perform an engine misfire inspection on your vehicle to help diagnose this issue and suggest any service needed.

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・Save up to 30%

Get a quote

What others are asking

Q: Vehicle not shifting out of park

Hello, if the shifter is disconnected, there is a chance that what ever holds the cable to the linkage is broken or worn out. The cable where it has become disconnected should be inspected to see what has failed. I...

Q: Interior lights

Hello. Pulling the fuse will cause all of the interior lights to stop working and will affect some of the other electrical systems also. If you are not getting the vehicle fixed any time soon then the only way to...

Q: White smoke coming from tail pipe.

While vehicle smoke can appear in a wide range of colors, white smoke from the exhaust is often an indication that the car is burning coolant in the engine. Coolant is normally found in the cooling system and can enter...

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 P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
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...