2000 chevrolet tahoe 4.3L the engine run rough at idle the spark plugs and wires been replace when i disconnect the spark plug wires when the engine is idling there is no change in the engine i check for codes it show PO5O7, PO332, PO327, PO174, PO171, so i erase the codes and scan again and the code are PO300 that's the only code return how do i fix this problem rough idle or misfire? when i disconnet the mass airflow sensor the engine run better what all i need to do to fix the problem?
The code is for random misfire, multiple cylinders, as you've replaced the plugs and leads then I would check the coils and the fuel injection
"Coils- pack malfunctioning,or a bad wire, or a sparkplug
SOURCE: 2000 VW Jetta VR6 My
You may have a bad coil pack - try moving two of them around and see if the misfire follows the coil pack or stays at the same cylinder. If it follows the coil pack, get a new one. If it stays in the same cylinder, inspect your spark plug wires and make sure the plug is gapped correctly.
SOURCE: running rough at idle. no codes after a scan.
I don't know what kind of scanner you are using. usually when there is mode 6 data there was a fault code stored and the pcm recorded it. if this is a 4.0 they have a couple vacuum leak problems either at intake gaskets or egr o-ring at manifold. you can hook up a vacuum gauge and see if it bouncs at idle,make sure hook it up to vacuum souce that work give you an improper reading and cause engine to act up,you diag will be compromised. try like a powerbrake booster hose close to intale as possible. this is just a guess from info i have to help you with. you can maybe run a running compression test to see if you have a bad follower or valve. don't run engine too long like this though,you will see a problem in the valve train if there is one.
SOURCE: 2003 Tahoe Running rough, Idle irratic, Ck engine
Yes, replace the MAF, then check if the lean condition goes away. It should.
MAF's are sensitive to cleaning. Sometimes it works, other times it doesn't.
Basically this means that the the car's computer has detected that not all of the engine's cylinders are firing properly.
A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.
SymptomsSymptoms may include:the engine may be harder to startthe engine may stumble / stumble, and/or hesitateother symptoms may also be presentCausesA code P0300 may mean that one or more of the following has happened:
Faulty spark plugs or wiresFaulty coil (pack)Faulty oxygen sensor(s)Faulty fuel injector(s)Burned exhaust valveFaulty catalytic converter(s)Stuck/blocked EGR valve / passagesFaulty camshaft position sensorDefective computerPossible SolutionsIf there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
If there are symptoms such as 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 wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases 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.
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SOURCE: what causes 2000 taurus engine rough idle but no codes
I had a head gasket going when I have a rough idle. Just weeping coolant past the number 1 cylinder. When I pulled the head the piston was all shiny and steam cleaned. $500 dollars all good now.
Here are the most common causes of idle surge, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake
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