Car is running fine, then rough running then engine light comes on but it starts running smooth again. the light goes out after 2 or3 drive cycles. this has happend 3 time in a week. What is going bad?
Go HERE to read about engine misfire diagnosis and repair.
SOURCE: 1997 dodge caravan, 3.3 engine, runs rough sometimes
the 1st thing to do is go to any Kragen or Autozone parts store and have them run a trouble code test for the reason the light is on, it is free, then post that code back here.
SOURCE: Check engine light
A multi misfire may mean that one or more of the following has happened:
Faulty spark plug or wires, Faulty coil (pack), Faulty oxygen sensor(s), Faulty fuel injector(s), Stuck/blocked EGR valve / passages, Faulty camshaft position sensor, Defective computer.
The engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wire, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the the problems were faulty fuel injectors.
Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.
Good luck and hope this information helps, keep me posted, be glad to help you get the truck running 100% again. Not sure if your running a K&N air filter, and if you are there may be a flim of oil on the MAF sensor that is making you run lean. You may want to spray down the MAF sensor with a can of MAF cleaner.
SOURCE: 2004 Neon SXT cylinder misfire
TRY REPLACING THE CRANKSHAFT POSITION SENSOR..HAVE SEEN THESE CAUSE MISFIRES AND LOW VOLTAGE DTCS AS PCM THINKS VEHICLE IS NOT RUNNING..ALTERNATOR MAY NOT BE PUTTING OUT PROPERLY
SOURCE: code papa 1391 misfire ( check eng lite on)& blower motor hi only
P1391 TROUBLE CODE IS INTERMITTENT LOSS OF CAM OR CRANK SIGNAL..WHAT SIZE ENGINE IN YOUR CAR?2.7/3.2/3.5?SOME MORE INFO WOULD HELP..ALSO YOUR HEATER FAN PROBLEM SOUNDS LIKE A FAULTY HEATER RESISTOR..PICK UP A NEW ONE..FAIRLY INEXPENSIVE..LOCATED IN HEATER HOUSING ON RIGHT SIDE UP UNDER DASH..IF YOUR NOT SURE HOW TO REPLACE..CONSULT A PROFESSIONAL..
SOURCE: MIL indicates cylinder misfire on 1, 3, and 5
Check for
vacuum leaks on intake manifold,
the air tube between the air filter.
intake manifold vacuum hose.
===
clean throttle plate with Berryman carburator cleaner
SEE sample picture HERE
===
Also remove carbon built up behind the EGR valve and the EGR passage tube.
===
Vacuum leak WILL offset the intended 14.7 to 1 air fuel ratio.
More un-metered air (leaks) will lean out the fuel mixture.
Use small amount of Berryman carb clearer at potential air leak area will help you identify trouble spot.
At idle,just spray and listen for the RPM surge.
The in-rush of carb clearer will increase the RPM on the motor.
Record the problem spot(s) and address it later.
===
EGR carbon built up require 2+ hours to clean from start to finish.
You will need a new EGR base gasket before your start.
Locate and remove the EGR valve after the vehicle is cool down.
Carefully record the connector and vacuum line (for older vehicle) location by drawing an easily to follow diagram.
Remove the EGR valve.
Inspect the location of the carbon built-up inside the valve and the EGR passage tube.
SOAK these areas with WD-40 spary.
You will need a small screwdriver,cloth hanger and lot of newspaper and time to get this cleaning done right.
RE-SOAK the carbon and let it sit for over-night will also help.
One the last round,pass a shop vacuum of the EGR valve and the passage pipe.
Install the new EGR gasket and connectors.
Allow the vehicle to warm up outdoor to burn up any remaining WD-40.
Take it for a test drive.
Please rate my answer if it's useful to you.
Cheers,
Mustgo
PLEASE RATE THIS REPLY FOR ACCURACY
426 views
Usually answered in minutes!
×