I have a 2005 Silverado HD I recently had the motor replaced. Ever since i had the motor replaced my engine light comes on flashing at first in the morning. In the afternoon it comes on and stays on. I had the install mechanic take a look, and he kept getting a engine code stating random misfire. He figured out it was the number two and three cylinder. All the plugs and wires have been replaced and double checked. He proceeded to switch the coils and and injectors out for ones the were not showing this issue. This didnt fix the problem. My mechanic and i are both confused as to what could be causing this. Any help would be greatly appreciated.

 

How did he determine this? Did he have 303, 302 misfire with 300 code? What plugs did you put in? Can you feel a misfire? I'd say replace the plugs with new ones (yes I know you did), also if the problem persists wires. What do the spark plugs look like after you have had this problem?

 

From what he said a 300 code. Im not sure how he figured out it was the number 2 and 3 cylinder. He said he got a 300 code. He used AC Double Platinum spark plugs .40 gap. I cant feel any misifre at all. plugs look good. So i should try replacing those two plugs and wires???? Should i contact the engine company with this info???

 

Are all the plugs gapped the same? If not, try ALL of them gapped at .060

 

time for a compression check and a new mechanic...this is a basic test that a professional should be doing after ruling out ignition problems and fuel problems.

 

Well after doing all tests. Compression, coils, injectors, gaping etc. They determined that the #2 and #3 cylinders had anti freeze leaking into them causing misfire and engine light. The engine is being removed and replaced.