Tip & How-To about Chevrolet Chevy
These Vortec engines have a habit of eating caps and rotors very quickly. This leads to misfiring, stumbling and pops coming out the intake.
These engines use computer-controlled timing, which is why they don't even have timing marks. The distributor's only function is to select which cylinder the coil's spark goes to. As such, rotating the distributor has no effect on timing like it did on older engines, it only changes where the distributor cap's electrodes are in relation to the rotor at the time of spark. Setting the correct rotation of the distributor to point the rotor electrode directly at the correct cap electrode at the time of spark is called "indexing" the cap to the rotor. It requires some really fancy tools to do... usually.
In my case, the engine had misfire codes when I bought it (kept it from passing smog and got me a good deal on it). After about 10k miles on a new cap/rotor, the engine began to stumble and throw codes again. When I removed the cap, one side of the electrodes had corroded while the other side was clean. Rather than have the spark from the rotor reach around to the back side of the electrode in the cap, it was a shorter path to spark to the clean side of the next electrode over. This was the misfire condition.
The fix was pretty simple. I rotated the distributor a few degrees toward the corded side (i.e. i put the cap electrodes closer to the position I could tell the rotor was in when sparking) and replaced the cap and rotor. The next cap and rotor went 20k miles, but again corroded on the same side. I rotated the distributor a couple degrees more and again changed the cap and rotor. This cap and rotor have been on the engine ever since. No more issues.
That is a simple but effective garage technique for indexing the cap to the rotor. The distributor cap will tell you everything you need to know.
Posted by Dennis... on
Feb 13, 2017 | 1999 Chevrolet Silverado 1500
Jun 23, 2012 | 2002 Dodge Caravan
A code P0300 may mean that one or more of the following has happened:
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders ( 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 (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
Jan 23, 2011 | 2004 Kia Amanti
Jan 11, 2011 | 2004 Acura MDX
Oct 29, 2009 | 1999 Chevrolet Silverado 1500
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