Vehicle: Chevrolet Blazer 2000 V6 4.3L Engine 4WD 234,000 Miles
When accelerating, upon reaching about 1500 RPM through about 2250 RPM the engine misfires in first gear (occasionally 2nd gear). It tends to do this for about 15 minutes after the vehicle is started (completely to even slightly cold, it stops once it warms up enough) roughly 5-10 start/stops in that 15 minutes. Once a higher gear is reached it complete stops misfiring in the indicated RPM range. There is no check-engine-light or any other lights that come on.
It appears that when the gas tank is full that it runs a bit better. Could this imply the problem is fuel related? (i.e. Fuel pump, fuel injection, etc)
Yesterday I replaced the following:
- Air & Oil Filters (including Oil change)
- Spark plugs (all six)
- Belt (had a squeak previously, unrelated but figured I'd mention anyways).
The spark plug wires are relatively new as well as the rotor & rotor cap (year or two old at most).
I had the same problem about a year or two ago and it was "fixed" by replacing the wires, rotor, & cap until about a couple weeks ago. The misfiring is back but the wires, rotor, & cap still seem too look new & good and I replaced the above.
- Seeing that replacing the rotor & cap previously fixed my problem, should I do it again?
- I would imagine that something else has to be causing the problem, should the rotor & cap need replaced this often? If not, what could be causing them to wear down so quickly?
- What steps should I take to troubleshooting the issue myself? Should I be looking for something specific? I'm good at self-teaching, I'm just not sure what I'm supposed to be looking for so I can teach myself to fix it.
It will be a week or two before I get enough money to take it to a shop to have them tell me what is wrong with it, I was hoping to exhaust other possibilities until then, possibly figuring out what the issue is and fixing it myself instead.
On another note, I'm not sure if it could be related (as my knowledge of vehicles is limited) but, the vehicle does currently (and has had for a while) a slow oil leak coming somewhere high up on the vehicle as the oil is usually all over the under-body.
I changed the spark plug wires and the misfires still happen. However the misfires stop (for that particular acceleration) if I give it a bit more gas than usual. Does this change anything in regards to figuring out what the issue is?
The check-engine light finally came on. Error code
P0300 Random Multiple Misfires. When I get the chance I plan on checking my Vacuum lines for leaks. I'll update again afterword with results.