Impala Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter #1
Ok... this one has been making me scratch my head. Ran the codes for my Impala (K code) 3.8 V6 and it came up with a P0300 - random misfire. Here's the symptoms.
1.) Rough idle for a few minutes, ranges from 800-1250 rpm for approximately 2 minutes
2.) Smell of gasoline around the tail pipe and the fuel rail
3.) Loss of power when accelerating (pressing the accelerator over 1/4 through any gear
4.) Engine shakes when you push the engine too hard (see previous problem)

Ok... here's what I've done to help rectify this little problem that still keeps happening.

1.) replaced all plugs and wires
2.) new throttle body gasket and cleaned throttle body. This thing was black as night and highly caked when I pulled it off.
3.) New bank 1 sensor 1 O2 sensor.
4.) Higher octane fuel with SeaFoam additive and Heat additive.
5.) New vacuum hoses and adapters

What else am I missing? :bang:
 

·
Registered
Joined
·
95 Posts
mine was caused by the fuel vapor vent solenoid. it sits on the left side if you are looking at the engine right above the fuel injectors.
 

·
Mr. Handy
Joined
·
6,289 Posts
Sounds like a maf issue or leaking fuel pressure regulator.

Did u clean the maf?
 

·
Registered
Joined
·
5 Posts
Discussion Starter #6
Pull the vacuum hose off the fuel pressure regulator. It should be dry and no signs or real smell of fuel. Its wet or wreaks of fuel you need a few one.
Update.... replaced fuel pressure regulator and still have the same issue. Checked the voltage from the coil packs and it is reading right at 12VDC, so that isn't the issue. Have yet to get my fuel pressure gauge (back) and test to see where the real issue lies. On the positive side, once I do figure out what it is, the car should run like new... considering almost everything under the hood will be new by the time I'm done with it.
 

·
Registered
Joined
·
2 Posts
CODE 300 MISFIRE SOLVED:
My 2004 Impala was shaking and vibrating at idle...all the usual signs that come with the engine light and code 0300 multiple cylinder misfire. I swapped the evaporator solenoid and was walking through the easiest items first - following the fuel channel (because it was multiple cylinders, I wrongly assumed it was ALL cylinders.) Before diving into the rear evap works, I decided to check the plugs and wires. I pulled #2 and #5...neither had an effect on the engine running and also did not shock me... Upon checking 1, 6, 3, 4 they all put on a firework show popping my bare hand furiously...so much so I couldn't reconnect them. I shut the car off. The 2/5 coil pack was clearly bad. Off to the junkyard...quick trip and $5.99 later, the Impala was running better than it has in all the time I've owned it. I'll do a full tune up soon but I wanted to share this quick lesson in beginning with the obvious/easiest item first.
 

·
Registered
Joined
·
2 Posts
How do your injectors look? Carbon fouled injectors will also give you the P0300 code.
I did not pull the plenum and dive down to the injectors. Swapping the coil pack ended the misfire, eliminated the code and clearly has the car running well. It has more acceleration power and purrs like a sewing machine. For me, no need to tear into anything else. However, I agree with your thought process. If this hadn’t solved my issue, injectors would certainly be on my list.
 
1 - 9 of 9 Posts
Top