It started idling rough when I turned on the heater last night. Every stop light the idle continually felt like it dropped & then jumped back up. Could feel the vibration. I didn't notice the rpm guage changing, but could really feel the roughness. Earlier that day I added Lucas fuel system cleaner & that night it started running bad again. (The day before I had the fuel filter changed & it was running smother) 3 weeks prior it was running bad & the check engine light came on for a day & then went off. Took it to my mechanic & all it said was a misfire, so he changed the plugs & wires. (He said he noticed signs of arching on 2 of the plugs & some spots on the wires) I can't afford to keep dumping money into it trying to figure out what's wrong.
Misfire can be caused by a few things. weak spark, low fuel pressure, to much fuel, vaccum leak. a simple check on this engine is to remove vaccum line from fuel pressure regulator, on fuel rail, driver side of engine. if you crank engine, and fuel leaks out vaccum port on regulator, its ruptured and causing rich fuel mixture. try that and let me know.
SOURCE: check engine light 2004 GMC Yukon
When my check engine light went on, it was a oxygen sensor
SOURCE: 2001 Tahoe: Hard to start, idles rough, check engine light on.
Flashing check engine light is missfire, fuel pump probably causing multiple tries to start.Having to build fuel preasure,vac leak on one side of intake probably causing rich/lean condition.Also check back preasure to cat ,Sound like you are moving down right track.Mas air flow would probably set lean code bank1 and lean code bank2
SOURCE: My 2003 GMC Sierra Idles Rough And Cut Off
Before replacing the O2 sensors, I would check the fuel pressure. You may also try to have someone pull a trouble code from the powertrain control module to verify why the engine light is on. Do not replace any parts until this is done, otherwise your going to be guessing at the root cause, and it will get expensive with part replacement.
Testimonial: "Trouble code P0101 {Mass Air Flow}and code P0332 Knock Sensor.Thanks i saved a lot money."
SOURCE: rough idle when cold
mcdevito75 here, Sounds like a faulty voltage regulator, it"s 1 unit with the alternator, change the alternator, also the alt. supplies juice to the ignition switch, distributor abd plugs, thus a rough idle due to bad alternator.
179 views
Usually answered in minutes!
×