Sunday, October 01, 2006

P0304 Code misfires on cylinder for 1999 S10 Truck with 4.3L engine


My truck has a pronounced miss on idle but goes away when I rev it up. When I scanned for codes, #4 cylinder is missing. I tried relocating the spark plugs and wires of this cylinder but the code remained the same (miss at #4 cylinder). I suspect this problem is mechanical but can you guide me?

ATS Advisor:

One of the quickest ways to find if your #4 cylinder is OK is to take a compression test on all cylinders and compare it with #4. You can also hook up a vacuum gage and watch it while your engine is idling. If the needle of the vacuum gage is fluctuating and not steady, that is a sure sign of cylinder valve failure. Finally, you can measure the resistance of each injector and compare them also.

ATS Tip:

If you confirm from above that your problem is mechanical, take out the engine valve cover so you can inspect the rockers and valve train.


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