P0300 Engine Misfire Repair Trick

Question:
1999 Chevy Monte carlo 3400 V6 SES light problem. Finally got a OBD 11 tester and i have a P0300 and P0302, or a misfire in #2 cylinder. Rechecked plug and wire, replaced wire, replaced coil for that cylinder. Sounds a bit better but still idles like a misfire, tester shows a misfire that is the only bad cylinder whats next, resistance on the injector, or would that have shown up on the tester?

Answer:
Thank you for the tip/donation. Assuming there is no engine mechanical problem with that cylinder- like a rocker arm stud has pulled out of the cylinder head, most probable cause is the injector. Scanners dont detect specific problem (injector bad) just the type of fault. Our injectors today dont usually fail because of low resistance anymore. They almost always fail because they are plugged. See picture below.

Here is a little trick, with the engine at idle, and missing, take a socket extension and tap the injector. Very lightly at first a few times, then a LITTLE harder if it has not cleared up. Be careful not to tap too hard and crack / punch hole in the injector. This procedure will almost always free-up a stuck injector. If it does, it may quit again in a day or two, or may last a month- hard to say. If the injector does free-up, would suggest an injector cleaning service and fuel filter after replacing the bad injector.

Question:
Problem with my 1997 Chevy Monte Carlo LS. 3.1L V6 engine Check engine lights flashing and OBDII codes p0300. Change all sparks plugs and wires. Why does my check engine light have this code p0300. We replaced coils and spark plug wire.

Answer:
First you need to find out which cylinder(s) is misfiring. If plugs and wires were replaced, another common cause for misfiring is a burned / corroded ignition coil. That should have been obvious while replacing the plug wires.

Question:
Problem with my 1995 Monte Carlo Z34. 3.4 DOHC. Work done to repair this problem = Replaced Idle Air Control Valve. My 3.4 idles VERY rough and dies cold. When warm the idle is somewhat erratic and although a little high it is tolerable. I cannot find any vacuum leak which is what I suspect. I replaced the idle air control valve and am now suspecting the EGR (it is digital). I'm not sure if it can be cleaned or not...... Any suggestions?

Answer:
This IS a classic sign of a vacuum leak on the Dual Overhead Cam Motor (DOHC). Especially the lower intake manifold gaskets as they meet the head, the PCV valve pipe on the drivers side rear of the rear cylinder head, or the brake booster vacuum hose. Concentrate spraying carb cleaner on these areas when warmed up to see if the idle will change. Be sure to stay away from any ignition source, as the spray is VERY flammable.

I recently purchased a 2005 Chevy Monte Carlo here it is only 10 days later and it's idling so high that I don't even have to put my foot on the gas it just takes off all by itself but you have to keep your foot only on the brake at all times. Please help?!
 If the check engine light is on, you need to have the codes scanned. You may have a problem in the Electronic Throttle Control (TAC). Or maybe it just needs a cleaning of carbon from the throttle.

My 2007 Chevy Monte Carlo doesn't want to take off fast it takes time an then it shakes an the rpm moves it self.
 Could be a lot of things. Engine misfire, low fuel pressure, MAF sensor, ECT. Get a scan of the computer codes even if the check engine light is not on.

Car had a random multiple misfire. I changed the spark plugs, wires, distributor cap, rotor button and 6 of 8 fuel injectors. The car ran fine after the work but the next day it started right back with the same thing.
 If after changing all that, and basically guessing, the car is not fixed. That is why we always stress doing proper diagnosis. If that were done, you would have saved a lot of time and money. The problem depends on what cylinders were misfiring. If they were all the Odd numbers, then this may be a common problem of the left catalytic converter being plugged. If it only happens when cold, that could be an intake manifold gasket leaking vacuum. You could also have a contaminated gas. A sample would need to be taken.