Having problems with your 1997 Oldsmobile Aurora ?

97 olds aurora code p0300. l have changed plugs,wires,coil packs and checked for vav leaks and compresion all good injectors good. but stil have code p0300. i have 3 cylinders not working #2,6,and 5 could sure use some help. thanks

Posted / edited by AnonymousUser on : 03-08-2020

Answers :

Explanation: The powertrain control module\015\012 monitors the crankshaft speed and has detected a misfire condition. \015\012Probable cause: 1. Ignition system fault-spark plugs, ignition wires, \015\012coil. 2. Vacuum leak 3. injector fault. high or low fuel pressure
Since I just fought with this on a 97 Grand Am. We found 17lbs. gas pressure at high idle. (very low) The car idled fine but would not run when hot. Please, please, please get the gas system checked first. Would have saved me two months of "trying" things. Replacing the fuel pump is expensive and complex. Knowledge about the electric and fuel system a must.
Below are some tips for resolving a code 300. Have you taken the injectors out and watched them squirt? Unfortunately, I do not have a manual for your car.
\015\012Random misfire troubleshooting:
The engine computer sets these codes when the crankshaft position sensor indicates rpm hunting under constant external conditions. Therefore, it is very difficult to distinguish genuine misfiring cylinders from generalized rough running.

Random electrical misfire:
If the cause is electrical, it is in the ignition system that produces the signal to the coil(s). In older engines, this might be due to a failing ignition modulator or pickup coil in the distributor. In modern engines, it might be a loose, failing, or poorly connected crankshaft position sensor (or camshaft position sensor in those engines that use this sensor for spark timing). This condition may or may not set an OBD II trouble code. Because of the large variation in ignition systems, I recommend you get the wiring diagram for your ignition system to see what components may be the cause of an inconsistent ignition signal to the coil(s). In rare cases, the problem may be with the modern ignition control, engine control, or powertrain control module. The problem may also be with general deterioration of the ignition wires. This condition can be verified by running the engine in a dark environment and watching for sparks jumping off the coil or wires.

Air/Fuel causes of a random misfire:
For the issue to be identified as a misfire, the changes in conditions in the cylinders must be rapid rather than gradual (such as in the case of a hunting rpm). These kinds of changes may be caused by unsteady airflow in the intake or inconsistent injector operation. Always check for a clean throttle body and idle air passage as well as idle air control motor operation. Also check the EGR valve operation and flow path. There may be specific tests you can run on these valves for your car. Consult a manual if you want to check these out carefully. Most of these components can be cleaned with good old-fashioned carb cleaner. It's also a good idea to make sure your vacuum operated fuel pressure regulator (if you have one) isn't drawing fuel into the intake manifold through a torn diaphragm.
Random injector issues are rare but may be caused by dirty fuel or worn out injectors. Another possibility here is a camshaft position sensor malfunction, but this will usually set another trouble code. In rare cases, injector timing and pulse width irregularity can be caused by the computer itself.
Repair Help & Product Troubleshooting for 1997 Oldsmobile Aurora

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